[Federal Register Volume 59, Number 212 (Thursday, November 3, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-26625]


[[Page Unknown]]

[Federal Register: November 3, 1994]


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Part II





Department of Transportation





_______________________________________________________________________



Research and Special Programs Administration



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49 CFR Part 171 et al.




Cargo Tanks; Miscellaneous Requirements; Final Rule
DEPARTMENT OF TRANSPORTATION

Research and Special Programs Administration

49 CFR Parts 171, 173, 178, and 180

[Docket No. HM-183C; Amdt. Nos. 171-129, 173-240, 178-105, 180-7]
RIN 2137-AC37

 
Cargo Tanks; Miscellaneous Requirements

AGENCY: Research and Special Programs Administration (RSPA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: RSPA is amending certain requirements for the manufacture, 
qualification and maintenance of cargo tank motor vehicles. These 
regulatory actions are based on petitions for rulemaking, exemptions, 
National Transportation Safety Board recommendations, and RSPA 
initiative. The intended effect of these actions is to relax certain 
regulatory requirements and to reduce unnecessary economic burdens on 
industry where there will be no adverse effect on safety.

DATES: Effective date: January 5, 1995.
    Compliance date: Compliance with the regulations, as amended 
herein, is authorized immediately.
    Incorporation by reference: The incorporation by reference of 
certain publications listed in this final rule is approved by the 
Director of the Office of the Federal Register as of January 5, 1995.

FOR FURTHER INFORMATION CONTACT: Ronald Kirkpatrick, telephone (202) 
366-4545, Office of Hazardous Materials Technology, or Jennifer Karim, 
(202) 366-4488, Office of Hazardous Materials Standards, Research and 
Special Programs Administration, U.S. Department of Transportation, 
Washington, DC 20590-0001.

SUPPLEMENTARY INFORMATION:

I. Background

    On March 3, 1993, RSPA published in the Federal Register a notice 
of proposed rulemaking (NPRM) [Docket No. HM-183C; Notice No. 93-7; 58 
FR 12316] proposing to amend certain requirements for the manufacture, 
qualification and maintenance of cargo tank motor vehicles. Most issues 
raised in the NPRM relate to requirements that were adopted in final 
rules published under Docket No. HM-183/HM-183A (June 12, 1989, 54 FR 
24982; May 22, 1990, 55 FR 21035; September 7, 1990, 55 FR 37028; June 
17, 1991, 56 FR 27872). The final rules established three new cargo 
tank specifications designated as DOT 406, DOT 407 and DOT 412, and 
revised the structural design requirements for MC 331 and MC 338 cargo 
tanks. Voluntary compliance for manufacture of cargo tanks to these new 
or revised specifications was authorized beginning on October 1, 1990.
    As manufacturers began modifying their manufacturing operations to 
construct cargo tanks to the new requirements, they encountered certain 
technical problems which caused them to question changes they had 
endorsed several years ago. They raised issues relating to structural 
integrity, accident damage protection, use of dual function pressure 
relief devices, and certification by the American Society of Mechanical 
Engineers (ASME). Also RSPA received several petitions for rulemaking 
addressing certain issues not previously raised. In the NPRM, RSPA 
pointed out these concerns and other issues based on petitions for 
rulemaking, exemptions, and National Transportation Safety Board (NTSB) 
recommendations. The NPRM also announced a public meeting that was held 
in Chicago on March 24 and 25, 1993, to address issues raised in the 
NPRM.
    On March 8, 1993, RSPA published a final rule [Docket HM-183, 58 FR 
12904] granting an extension until April 21, 1994, for the continued 
construction of cargo tank motor vehicles to the MC 306, MC 307, MC 
312, MC 331, and MC 338 specifications. This action was granted to 
allow additional time for RSPA and industry to address certain 
technical issues concerning the manufacture of cargo tank motor 
vehicles to the DOT 406, DOT 407 and DOT 412 specifications, and to 
resolve certain concerns about the structural design requirements in 
the MC 331 and MC 338 specifications.
    At the March 24-25 public meeting, several significantly different 
views of design engineers and cargo tank manufacturers were identified. 
Additionally, preliminary results were presented of an advanced 
structural evaluation (using finite element analysis) of the MC 331 
cargo tank which raised questions in regard to stress levels in areas 
of concentrated loadings.
    On January 12, 1994, RSPA published a final rule [Docket HM-183, 58 
FR 1784] granting another extension until August 31, 1995, for 
continued construction of cargo tank motor vehicles to the MC 
specifications. The final rule also announced a public meeting in 
Washington, D.C. on February 7-8, 1994.
    At the February public meeting, RSPA obtained clarification of 
certain comments received in response to the NPRM and also obtained 
additional supporting data on certain alternate proposals offered by 
industry. In addition, RSPA sought information to resolve the remaining 
issues on structural integrity, accident damage protection, use of dual 
function pressure relief devices, and ASME certification of low 
pressure cargo tank motor vehicle manufacturers.

II. Summary of Comments

    RSPA received over 50 written comments in response to the proposals 
contained in the NPRM from trade associations, cargo tank manufacturers 
and repairers, manufacturers of cargo tank parts and equipment, and 
Federal, State and local agencies. RSPA has considered all comments, 
public meeting transcripts and petitions in the development of this 
final rule.
    In the NPRM, RSPA informed industry that the following items would 
be open for discussion at the March public meeting:
    1. Application of the ASME Code to DOT 400-series specification 
cargo tank motor vehicles.
    a. The feasibility of citing all sections of the ASME Code that 
must be met in construction of DOT specification cargo tank motor 
vehicles as opposed to citing only those sections that do not apply.
    b. The development of a consensus standard containing procedures 
for quality control, welding and design as an alternative to the 
procedures contained in the ASME Code.
    2. The progress of the industry on development and testing of dual 
function vents, reclosing pressure relief devices capable of reseating 
with the loss of less than one gallon of lading, and self-closing 
systems for vacuum-loaded hazardous waste tanks.
    3. The regulatory proposals contained in the NPRM.
    Most commenters supported application of the ASME Code. One 
commenter stated that his company, which had initially opposed becoming 
ASME certified, has benefited from the expertise of the National Board 
inspector.
    The ASME Code is an internationally recognized consensus standard 
for the design and construction of pressure vessels. It is also the 
only proven quality control standard for pressure vessels and cargo 
tanks.
    The Cargo Tank Manufacturing Association (CTMA) submitted a draft 
quality control manual for review. CTMA recommended that RSPA recognize 
the manual, which includes quality control procedures, as an 
alternative to requiring manufacturers to have an ASME ``U'' stamp or 
National Board ``R'' stamp. The use of the alternative standard 
recommended by CTMA is not equivalent in scope and detail to the ASME 
Code and is not included in this final rule.
    It has also been brought to RSPA's attention that some ``U'' stamp 
and ``R'' stamp holders may believe they are not required to apply all 
provisions of the ASME or National Board quality control program for 
work on non-ASME DOT specification cargo tanks. When the regulations 
requiring cargo tank manufacturers and repair facilities to hold ``U'' 
and ``R'' stamps were promulgated, RSPA stated in the preamble 
discussions of the final rules and at public meetings that major 
provisions of the ASME or National Board quality control programs would 
apply to all work on DOT specification cargo tanks. Such provisions 
include welder qualifications, welding techniques, and quality control 
procedures. For instance, refer to the preamble discussions in the 
following final rules: ``B. Cargo Tank: Manufacturer Qualification, 
Registration, Quality Control, and Certification,'' (June 12, 1989, 54 
FR 24984); ``Section 180.413 (Repair, Modification, Stretching, and 
Rebarrelling),'' (September 7, 1990, 55 FR 37044).
    One commenter stated that specifying all applicable sections of the 
ASME Code, rather than providing exceptions to sections that are not 
applicable, would provide greater assurance to engineers and designers 
that they have not overlooked an obscure section of the ASME Code. The 
commenter did not provide RSPA with any suggested wording for 
implementation of the recommendation.
    The National Propane Gas Association (NPGA) submitted a report on 
the structural integrity of the MC 331 specification cargo tank. NPGA 
recommended uniformity in design loading requirements for all DOT 
specification cargo tanks. RSPA will consider the design loading 
requirements for MC 331 and MC 338 specification cargo tanks in a 
future rulemaking. The report is available for review in the public 
docket.

III. Section-by-Section Review

    This review by section discusses only significant comments received 
to the proposals in the NPRM, changes made based on alternative 
proposals offered by commenters, and clarifications to certain 
provisions based on RSPA's initiatives. For those provisions that are 
adopted as proposed, readers are referred to the preamble discussion in 
the NPRM.

Section 171.7

    The Truck Trailer Manufacturers Association (TTMA) submitted a 
petition for rulemaking (P-1236) requesting RSPA to incorporate by 
reference the latest editions of the ASME Code from the 1986 Edition 
and Addenda through 1985 to the 1992 edition and Addenda through 1993, 
and to update the National Board inspection Code from the 1983 Edition 
to the 1992 Edition. RSPA has reviewed these updated standards and 
agrees the latest editions should be referenced. The table in paragraph 
(a)(3) has been revised accordingly.

Section 173.33

    Consistent with changes made in Sec. 180.405(h) in this final rule, 
a new sentence is added to paragraph (d) stating that the venting 
requirements of the original DOT cargo tank specification must be met 
whenever a pressure relief valve is modified to a more recent 
specification. See preamble discussion for Sec. 180.405(h). Similarly, 
in view of changes made in Secs. 178.337-11 and 178.338-11 in this 
final rule, a new paragraph (h) is added to inform shippers that 
certain MC 331 and MC 338 cargo tanks manufactured after August 31, 
1995, must have remotely controlled, internal, self-closing stop 
valves. See preamble discussion for Sec. 178.337-11.

Section 173.225

    Commenters supported the proposal to revise paragraph (e)(2) to 
authorize the use of MC 307 and DOT 407 cargo tank motor vehicles for 
certain organic peroxides. However, one commenter opposed allowing the 
use of MC 307 cargo tanks for all organic peroxides. This commenter 
misunderstood the proposal. Note 14 to the Sec. 173.225(b) Table 
authorizes bulk packagings for only a few organic peroxides. Therefore, 
paragraph (e)(2) is adopted as proposed in the NPRM.

Section 173.315

    For cargo tank motor vehicles in chlorine service, changes in 
requirements for hose, piping or tubing to be carried on the vehicle 
and in requirements for testing angle valves, as proposed in the NPRM, 
are adopted as paragraphs (o)(1) and (o)(2) respectively.

Section 178.337-1

    Paragraphs (a)(3) and (e)(1) are revised to correct certain section 
references and paragraph (e)(2) is revised to authorize the use of 
ceramic fiber/fiberglass insulation for cargo tanks in chlorine service 
as proposed in the NPRM.

Section 178.337-9

    As proposed in the NPRM, the restriction is removed against 
mounting or carrying on a cargo tank motor vehicle any hose, piping or 
tubing used in loading or unloading; paragraphs (b)(7) (ii) and (iii) 
are redesignated as (b)(7) (i) and (ii) respectively.

Section 178.337-11

    In response to NTSB recommendation H-90-91 dealing with release of 
sulfur dioxide from an MC 331 cargo tank during unloading, RSPA 
proposed revision of requirements for remotely controlled self-closing 
stop valves on liquid or vapor discharge lines on newly constructed MC 
331 cargo tank motor vehicles. Currently found at paragraph (a)(2), 
this requirement applies only to equipment intended for transportation 
of a flammable liquid, a flammable compressed gas, hydrogen chloride 
(refrigerated liquid) or anhydrous ammonia. RSPA proposed to broaden 
the requirement to include all compressed gases. This revision also was 
proposed for MC 338 cargo tanks.
    Both the NTSB and the Compressed Gas Association (CGA) commented on 
RSPA's proposal to require remotely controlled internal self-closing 
stop valves. While supportive of RSPA's proposal, NTSB stated:

    Although the Safety Board is aware that MC 331 cargo tanks are 
predominantly used for the transportation of flammable and 
nonflammable compressed gases, the hazardous materials regulations 
(49 CFR Parts 171 through 180) do authorize these tanks to be used 
for the transportation of other classes of hazardous materials such 
as flammable liquids and poisons. The Safety Board believes that 
remote controls for internal shut-off valves should be required for 
any hazardous material that is authorized to be transported in an MC 
331 cargo tank. Further the Safety Board believes that all MC 331 
and MC 338 cargo tanks currently in hazardous materials service, and 
not just newly constructed tanks, should also be equipped with 
remote controls for the internal shut-off valves. The Safety Board 
has consistently urged the DOT to eliminate ``grandfathering'' 
clauses that permit hazardous materials to be transported 
indefinitely in containers or vehicles that fail to meet current 
minimum safety standards. The Safety Board believes that RSPA should 
require all MC 331 and MC 338 highway cargo tanks in hazardous 
materials service to be equipped with remote controls for internal 
shut-off valves by a specific date.

    On the other hand, the CGA believes that remotely controlled shut-
off valves should not be required for nonflammable ladings. CGA stated 
that ``operating experience for the nonflammable compressed gases does 
not warrant the addition of this restriction which would add cost 
without providing additional safety benefit.''
    After consideration of both comments, RSPA has revised the wording 
in Secs. 178.337-11 and 178.338-11 to require the use of remotely 
controlled internal self-closing stop valves on any cargo tank motor 
vehicle certified after August 31, 1995, that is intended for the 
transportation of hazardous materials other than argon, carbon dioxide, 
helium, krypton, neon, nitrogen, and xenon. RSPA has excepted these 
particular gases because they pose a lesser degree of risk to public 
health, safety, and the environment in the event of their release 
during transportation. Many of the nonflammable refrigerant gases 
presently transported in cargo tanks are ozone depleters; some other 
nonflammable gases are toxic or noxious. RSPA will address the retrofit 
of existing cargo tanks with remotely controlled internal self-closing 
stop valves in a separate rulemaking action.

Section 178.338-9

    As proposed in the NPRM and adopted in this final rule, paragraph 
(c)(2) is amended by removing the definition of ``same design'' and by 
adding a reference to the definition of ``same design'' contained in 
Sec. 178.320. By referencing the definition in Sec. 178.320, minor 
design variations are allowed for MC 338 cargo tanks.

Section 178.338-11

    NTSB and CGA submitted comments to this section which were similar 
to their comments to proposed Sec. 178.337-11. As stated in the 
preamble discussion to Sec. 178.337-11 above, RSPA has revised the 
wording in Secs. 178.337-11 and 178.338-11 to require the use of 
remotely controlled internal self-closing stop valves on any MC 338 
cargo tank motor vehicle certified after August 31, 1995, that is 
intended for the transportation of hazardous materials other than 
argon, carbon dioxide, helium, krypton, neon, nitrogen, and xenon.

Section 178.345-1

    In paragraph (c), definitions for ``normal operating loading'' and 
``extreme dynamic loading'' are added. These terms are used in revised 
Sec. 178.345-3 in this final rule.
    Paragraph (i)(2) requires that the void space within the connecting 
structure of a cargo tank motor vehicle composed of multiple cargo 
tanks must be vented to the atmosphere by a drain of at least 1 inch in 
diameter. In the NPRM, RSPA proposed to remove the drain hole size 
restriction. RSPA also solicited information on suitable dimensional 
controls for these drains, how often these areas need to be inspected, 
the conditions revealed during such inspections, and the availability 
of equipment for inspecting these areas.
    Commenters expressed diverse views on the need to inspect these 
areas. The California Highway Patrol (CHP) strongly supported the need 
for periodic inspection of the connecting structures on cargo tanks 
used to transport all hazardous materials. CHP related information 
about three separate catastrophic failures of molten sulfur trailers 
that occurred due to fatigue cracking in the void space. All three 
cargo tank motor vehicles had been insulated, thus preventing any 
external visual inspection for shell cracks. CHP believes that if an 
internal visual inspection of the void space had been performed, 
evidence of cracking may have been detected prior to the catastrophic 
failures. CHP noted that equipment, such as fiber optics, borescopes 
and video cameras, is readily available for inspecting closed areas and 
is being used for pipeline, aircraft, oil well, and boiler inspections. 
Also, numerous contractors offering inspection and non-destructive 
testing services are available throughout the U.S.
    NTSB also concurred that regular and effective inspections of void 
spaces are essential. NTSB, however, expressed concern that HM-183C did 
not address the configuration of other appurtenances that could conceal 
corrosion that might lead to a failure of the tank wall. The NTSB 
recommendation H-83-30 called for periodic external visual inspection 
of surfaces obscured by appurtenances, structural members, etc.
    Several commenters who opposed inspecting these areas stated that 
double bulkheads and void spaces on MC 306 or DOT 406 cargo tanks in 
non-corrosive service do not experience the same degree of 
deterioration as MC 312 or DOT 412 cargo tanks in corrosive service. 
They stated that cargo tanks in non-corrosive service should not be 
subject to the same inspections. One commenter submitted to RSPA 
samples taken from bulkheads adjacent to void spaces of two scrapped MC 
306 carbon steel cargo tanks used in gasoline service for 14 and 15 
years. The commenter stated that neither tank showed evidence of 
corrosion at this location; the samples confirm this statement.
    TTMA stated there is little possibility of corrosion occurring in 
the void space of any tank, except on carbon steel cargo tanks in 
corrosive service. TTMA recommended that the connecting structure on 
self-supporting cargo tanks be thickness tested every two years for 
signs of corrosion. Several other commenters supported TTMA's comments. 
One commenter also suggested that the wording be revised to eliminate 
reference to the inspection opening but continue to provide for a 
drain. The commenter stated that the minimum acceptable size of any 
drain opening should be 0.5 inches diameter, which is large enough to 
insert a borescope or equivalent device.
    RSPA agrees with commenters that there has been no evidence of 
corrosion occurring in the void space of any tank, except a carbon 
steel cargo tank in corrosive service. Corrosion in connecting spaces 
has serious structural implications for self-supporting cargo tanks. 
The failure reported in the NTSB investigative report, containing 
recommendation H-83-30, involved a carbon steel MC 312 cargo tank semi-
trailer carrying hydrochloric acid; the failure occurred due to severe 
corrosion in the tank shell under a circumferential reinforcing ring. 
Therefore, paragraph (i)(2) is revised to require that the connecting 
structure in a carbon steel, self-supporting multi-tank cargo tank 
motor vehicle must have a single drain of at least 1.0 inch diameter, 
or two or more drains of at least 0.5 inches diameter, 6 inches apart, 
one of which is located on the bottom centerline. In addition, 
Sec. 180.407(i) is revised to require thickness testing of these areas 
as suggested by TTMA.
    RSPA believes that NTSB recommendation H-83-30, which calls for 
periodic external visual inspection of cargo tank surfaces obscured by 
appurtenances and structural attachments, is adequately addressed in 
current Sec. 180.407(d). Paragraph (d) requires that a periodic 
external visual inspection must be conducted of all major appurtenances 
and structural attachments on a cargo tank to detect signs of corrosion 
or damage.

Section 178.345-3

    Commenters expressed concern over the lack of flexibility in 
calculating compressive stresses for non-ASME DOT 400-series cargo 
tanks. They recommended that RSPA provide alternatives to ASME Code 
Section VIII, Division 1 UG-23(b) for calculating the maximum allowable 
compressive buckling stress in tank walls for low pressure cargo tanks. 
The static design and construction of all DOT 400-series cargo tanks 
must be in accordance with Section VIII of the ASME Code. Any DOT 400-
series cargo tank which is required to be certified to the ASME Code 
also must be designed in accordance with the Code's requirements for 
dynamic loading, including UG-23(b). This applies to DOT 407 cargo 
tanks with a MAWP greater than 35 psig and each tank designed to be 
loaded by vacuum, and to DOT 412 cargo tanks having a MAWP greater than 
15 psig.
    TTMA stated manufacturers believe the requirements in Sec. 178.345-
3(b) should be modified to allow several methods of analysis as 
appropriate for the cargo tank under consideration. Using the methods 
outlined in the ASME Code produces lower allowable compressive stress 
values, resulting in substantially thicker sheets for the DOT 400-
series tanks as compared with the MC 300-series cargo tanks.
    One commenter stated that while the UG-23(b) calculations may be 
appropriate for DOT 407 cargo tank with MAWP ratings between 25 and 35 
psig, this formula will rarely yield reasonable results for DOT 406 or 
DOT 412 cargo tanks having a MAWP of 15 psig or less. Commenters 
recommended two alternatives to the ASME UG-23(b) design calculations, 
both of which are formulas from engineering texts. One is from the 
``Alcoa Structural Handbook,'' 1960, page 156 and Table 23; the other 
is from ``Formulas for Stress and Strain,'' Fifth Edition, by Roark and 
Young, pages 554 and 555 and Table 35. The ``Alcoa Structural 
Handbook'' formula is as follows:

TR03NO94.000

where:
Ri/ts is greater than 200
E = modulus of elasticity of material at design temperature
Ri = inside radius of the shell (largest radius of non-circular 
cross-section)
ts = minimum thickness of shell less corrosion allowance
SbA = critical compressive buckling stress per the Alcoa formula
Sc = allowable compressive stress due to static bending loads

    The Roark and Young formula is as follows:

TR03NO94.001

where:

Ri/ts is greater than 10
SbY = critical compressive buckling stress per Roark and Young
v = Poisson's ratio

    Other symbols are the same as in the Alcoa formula, above.
    Based on the merit of these comments, RSPA is revising paragraph 
(b) to allow alternative methods for determining compressive buckling 
stress for DOT 400-series cargo tanks which are not required to be 
certified in accordance with the ASME Code. This allows manufacturers 
more freedom in the design of DOT 400-series cargo tank motor vehicles, 
particularly the DOT 406 cargo tank.
    RSPA solicited information on the structural integrity of cargo 
tanks and, in particular, the loading combinations that may be 
encountered during operation of cargo tank motor vehicles as prescribed 
in paragraph (c). Information was received from several commenters 
which indicated that the loadings from normal operating conditions are 
different from loadings experienced in extreme dynamic events. The 
normal operating loadings are more frequent in occurrence, but much 
lower than the extreme dynamic loadings.
    The requirement contained in current paragraph (c) only specifies 
extreme dynamic loadings. A cargo tank designer must determine which 
loadings, if any, should be considered as acting simultaneously. TTMA 
stated it is unlikely that extreme dynamic loadings will occur and 
highly unlikely that such loadings will occur at the same time. TTMA 
reported that if the extreme dynamic loadings are considered by the 
cargo tank designer as acting simultaneously, the resulting weight of a 
DOT 406 cargo tank would increase significantly. TTMA went on to state 
that such an increase in tank weight would have an adverse effect on 
public safety because it would cause a decrease in the number of 
gallons delivered each trip, increasing the number of trips and miles 
driven, thus increasing the probability of more accidents, personal 
injuries and fatalities.
    During discussions on structural integrity issues at the February 
1994 public meeting, the potential for changes in loading due to liquid 
movement was addressed. Commenters generally agreed that while 
significant lading movement can occur during partially loaded 
conditions and that such movement cannot be disregarded by cargo tank 
designers and vehicle operators, the variables involved are more than 
can be comprehensively dealt with at this time. The general agreement 
was that the highest stress conditions on most cargo tank 
configurations occur when the cargo tanks are full. Discussions on how 
to combine the loadings in calculating the structural integrity 
requirements have been going on for a number of years. RSPA agrees with 
commenters that the loadings currently in the HMR are based on extreme 
conditions that would be realized only on a rare occasion, if ever. 
Thus, based on recent information presented at the public meetings and 
written comments received in response to the NPRM, RSPA concludes that, 
for the design and construction of cargo tanks, it is best to consider 
separately the effects of normal operating loadings, which are known to 
act in combination, and the effects of extreme dynamic loadings, which 
are not expected to act in combination with each other. Therefore, in 
this final rule, RSPA is revising paragraph (c) to provide structural 
design requirements that will be more reflective of conditions 
encountered by cargo tank motor vehicles. These revisions will require 
cargo tank designers to consider normal operating loadings to be acting 
simultaneously, except that longitudinal acceleration and deceleration 
cannot occur at the same time. Also, extreme dynamic loadings must be 
considered in separate calculations; these loadings may be considered 
to be acting independently.
    Paragraph (d) prescribes design calculations that should be 
considered to account for stresses due to impact in an accident. For 
consistency, the accident damage requirements contained in current 
paragraph (d) are moved to Sec. 178.345-8(e) where other accident 
damage protection requirements appear. Also, consistent with other 
changes made to this section, paragraphs (a) (1) and (3) are amended by 
removing the reference to paragraph (d) of this section.
    Paragraph (e) is editorially revised, for clarity and consistency, 
by changing the word ``wall'' to read ``shell and heads'', and 
paragraphs (e) through (g) are redesignated as paragraphs (d) through 
(f).

Section 178.345-5

    Commenters supported the proposed change in paragraph (b) that all 
fittings and devices mounted on a manhole cover must withstand the same 
static internal fluid pressure as that required for the manhole. 
However, commenters requested a revision to clarify that fitting and 
device manufacturers are responsible for testing and certifying the 
structural integrity of their products. RSPA agrees with the commenters 
that the fitting and device manufacturers should be responsible for 
ensuring the integrity of their components. Therefore, the proposed 
provision is revised for clarity and added as new paragraph (f).
    Another commenter suggested that paragraph (e) be revised to 
require that each manhole cover must be marked with the date of 
certification. RSPA will consider this comment in a future rulemaking 
action.

Section 178.345-6

    A minor editorial change is adopted as proposed in the NPRM.

Section 178.345-8

    Commenters recommended several changes to the accident damage 
protection requirements. They requested that all accident damage 
protection devices be designed so that calculated stress under the 
conditions prescribed not exceed the ultimate strength of the material 
of construction. They pointed out certain inconsistencies in the design 
criteria specified in this section. For example, in paragraph (d), the 
design stress for accidents involving longitudinal deceleration is 
based on ``the lesser of the yield strength or 75 percent of the 
ultimate strength''; the general requirement for accident damage 
protection in paragraph (a)(3), is based on ``75 percent of the 
ultimate strength''; while bottom damage and rollover damage 
protection, in paragraphs (b) and (c), both are based on the ``ultimate 
strength.'' RSPA agrees there is merit in using the same criteria 
whenever possible. Therefore, in this final rule, the design of all 
accident damage protection devices is based on the ultimate strength of 
the material of construction.
    The primary purpose of accident damage protection is to prevent the 
release of hazardous lading from a cargo tank in the event of an 
accident. For example, during an accident involving the maximum level 
of longitudinal deceleration expected, if the front head of a cargo 
tank experiences stress levels above the yield point of the material of 
construction, the head will bulge or distort. However, if that deformed 
head continues to contain the lading, the intent of this requirement 
has been met. In a practical sense, good engineering practice provides 
for factors of safety when analytical methods are not well established 
and when safety considerations call for reducing the probability of 
failures.
    When an accident imposes loads on the cargo tank wall, the material 
of the wall, however, must be stronger than the accident damage 
protection device. For example, in a rollover accident, the portion of 
the cargo tank wall to which a rollover protection device is attached 
should not fail before the rollover protection device fails. The design 
stresses in the protection device itself can be based on the ultimate 
strength of the material, but the loads transmitted to the cargo tank 
wall must be based on a more conservative value. This can be achieved 
by use of factors of safety.
    Accordingly, paragraph (a)(3) is revised to base design stresses on 
the ultimate strength of the material with a 1.3 safety factor (i.e., 
the reciprocal of 0.75 times ultimate, rounded).
    Commenters have stated that most impacts on bottom damage 
protection devices in accidents occur directly from the side of the 
vehicle. TTMA has stated that any piping at the bottom of a tank is 
protected fore and aft by the running gear of the cargo tank motor 
vehicle or its towing vehicle. Contending that reduced forces of impact 
can be expected from front and rear, TTMA petitioned for a reduction 
from 155,000 pounds to 27,000 pounds fore and aft along the 
longitudinal axis of the vehicle. RSPA believes, however, that the 
possibility of impacts from the front is very real for trailers; for 
example, during turning maneuvers, or in the event that the towing 
vehicle rides over an obstacle such as a guard rail. On the other hand, 
impacts from the rear are less likely on trailers because of the rear 
suspension. Therefore, RSPA has revised paragraph (b)(1) to recognize 
that suspension components and structural mounting members can provide 
all, or part, of bottom damage protection. Additionally, in paragraph 
(b) introductory text, a second sentence is added to clarify that a 
single protection device may be used to protect outlets, projections 
and piping grouped or clustered together.
    Commenters stated that in the general rollover damage protection 
requirements, in paragraph (c), the wording ``enclosed inside'' could 
be misunderstood to require that closures and fittings must be 
protected from rollover damage on all sides--front, sides, rear and 
top. They also suggested that the protection devices be located no more 
than 48 inches from the closure or fitting. RSPA never intended to 
require that the component being protected be fully enclosed by the 
protective device. Also, RSPA does not agree with adding a dimensional 
location requirement. Rather than dimensional controls, one of RSPA's 
overall objectives is to provide performance requirements when 
appropriate. Therefore, paragraph (c) is revised to clarify the 
ambiguous wording.
    Commenters requested that in paragraph (c)(1), the tangential 
design load for rollover protection be reduced from 2 ``g'' to 0.5 
``g'' or 1 ``g.'' A commenter stated that ``neither industry nor 
government have any data to support what this rollover protection 
device strength should be'', contending that MC 306 accident damage 
protection has performed well, even considering findings of the NTSB 
study of overturn accidents. A commenter provided analytical data that 
indicated the internal bulkheads would be overstressed under 2 ``g'' 
tangential loads using the current MC 306 design.
    A February 4, 1992 NTSB investigation report on rollover accidents 
involving MC 306 and MC 312 cargo tanks recommended several actions by 
both RSPA and the Federal Highway Administration (FHWA). The NTSB 
report supported the earlier RSPA decision to increase the rollover 
design load in the horizontal plane from one-half the weight of the 
loaded cargo tank motor vehicle prescribed in the MC 306, MC 307 and MC 
312 specifications, to twice the weight of the loaded cargo tank motor 
vehicle prescribed in the DOT 406, DOT 407 and DOT 412 specifications. 
NTSB also noted that at this time, test results are not available to 
support this four-fold increase, but limited testing performed under 
RSPA and FHWA sponsorship for studies of release from dome covers 
indicate forces can easily exceed 2 ``g''. Additionally, NTSB 
questioned whether the load specified for the DOT 406, DOT 407 and DOT 
412 specifications are adequate in a typical rollover accident.
    RSPA agrees with comments that in some rollover accidents, cargo 
tank rotation is limited to 120 degrees or less, so that these 
horizontal forces do not come into play unless a roadside obstacle is 
struck. In such incidents, the side of the cargo tank absorbs most of 
the energy of the rollover. However, in other rollover incidents, cargo 
tank motor vehicles have rotated 180 degrees or more and rollover 
protection devices have failed.
    RSPA performed simple calculations to estimate the forces that 
would be expected to bring a sliding overturned cargo tank motor 
vehicle to a halt, at a variety of speeds and stopping distances. From 
the calculations performed regarding stopping distances, RSPA concludes 
that the design loads should not be decreased. FHWA will initiate a 
study aimed at developing a more refined understanding of the forces 
involved in cargo tank rollover accidents.
    For these reasons, RSPA rejects requests to lower the tangential 
design load. In many cases, manufacturers will find it necessary to 
develop new designs for overturn protection devices, perhaps with 
associated short-term increased cost, but with enhanced safety 
benefits. Several manufacturers already have developed satisfactory 
protection devices which meet these design criteria. In addition, RSPA 
has made several minor editorial revisions in paragraph (c)(1) to 
improve clarity.
    Paragraph (d)(3) prescribes that each cargo tank rear-end 
protection device and its attachment to the vehicle must be designed to 
satisfy the conditions specified in paragraph (d)(1) when subject to an 
impact of the cargo tank at rated payload, at a deceleration of 2 
``g''. Such an impact must be considered as being uniformly applied in 
a horizontal plane at an angle of 30 degrees or less to the 
longitudinal axis of the vehicle. Commenters requested elimination of 
the 30 degree angle for this impact load. They stated that most rear-
end collisions of trucks and trailers involve other vehicles and are 
``in line'', i.e., the longitudinal centerlines of the two vehicles are 
parallel at impact. TTMA pointed out that the National Highway Traffic 
Safety Administration (NHTSA) published a notice of proposed rulemaking 
[Docket No. 1-11, Notice 9; January 3, 1992], containing a proposal for 
rear impact guards and protection. The NHTSA proposal specified an 
impact only in the direction of the longitudinal centerline of the 
struck vehicle; it did not address angular impact. NHTSA's rear impact 
requirements are intended for the design of underride guards that will 
minimize impacts in occurrences where automobiles underride (i.e., 
slide under) the rear-end of large trucks and trailers. These 
requirements are intended to protect passenger occupants while RSPA's 
requirement for cargo tank rear-end protection is intended to prevent 
impacts to lading retention components that could result in the loss of 
hazardous material lading. Upon further review, RSPA agrees that 
requiring rear-end protection devices to withstand impacts at an angle 
of 30 degrees to the longitudinal axis of the vehicle is excessive. 
Therefore, paragraph (d)(3) is revised to reduce the angle of impact to 
10 degrees.
    A requirement contained in current paragraph (d) of Sec. 178.345-3 
specifying design stress for accidents involving longitudinal 
deceleration is revised and moved to new paragraph 178.345-8(e) in this 
final rule. The specified design stress is based on the ultimate 
strength of the material with a factor of safety of 1.3 (i.e., the 
reciprocal of 0.75 times ultimate, rounded). The use of 2 ``g'' as a 
reasonable maximum level for longitudinal deceleration in accident 
situations generally has been accepted by industry but commenters have 
stated that the reliability of strain gauge testing and finite element 
analysis is questionable when structures are loaded above the yield 
point. For this reason, cargo tank manufacturers who choose to design 
at this level may use performance testing to prove that tank heads and 
shell can withstand this 2 ``g'' loading condition. Alternate 
analytical methods or combinations of test and analysis may be used if 
they are accurate and verifiable.

Section 178.345-10

    This section specifies requirements for the pressure relief and 
vacuum systems on DOT 400-series cargo tank motor vehicles. It also 
specifies lading retention requirements for the pressure relief system 
in the event of an overturn. Numerous commenters suggested alternative 
provisions for pressure relief systems on DOT 400-series cargo tanks. 
Pressure relief valve manufacturers stated that they have found it very 
difficult to attain ``no loss of lading'' with valve designs capable of 
withstanding the characteristic dynamic pressure surge required by the 
regulation, especially at low design pressures.
    For these reasons, commenters requested that RSPA allow the loss of 
one liter of lading. If adopted, a properly functioning pressure relief 
valve could be expected to release no more than one liter of hazardous 
material in an overturn accident. This amount of liquid would be so 
widely dispersed by the motion of the vehicle as to cause minimal 
danger of fire or environmental damage.
    Cargo tank shipments of poisonous-by-inhalation (PIH) materials in 
Hazard Zones A and B are subject to special provisions which result in 
high working pressures, thicker tank walls and thermal insulation. 
Insulation moderates thermal gain, thus increasing the pressure 
differential between valve pressure settings and dynamic pressure; 
also, it cushions the impact of accidents. The net effect of these 
features makes it unlikely that even small releases of PIH lading will 
occur.
    RSPA believes allowing a minute release of other types of ladings 
in overturn accidents has greater safety benefits when compared with 
possible loss of an entire cargo tank load. Therefore, paragraph 
(b)(3)(ii) is revised to specify that after August 31, 1995, DOT 400-
series cargo tanks must be equipped with a pressure relief valve that 
will release no more than one liter of lading in an emergency situation 
before reclosing to a leak-tight position. In addition, editorial 
changes are made in paragraph (b)(3)(i) for clarity.

Section 178.345-13

    A paragraph heading, ``Leakage test.'' is added to paragraph (c) as 
proposed in the NPRM.

Section 178.345-14

    This section specifies cargo tank marking requirements. The 
California Highway Patrol recommended several substantial changes 
throughout this section that were not proposed in the NPRM. While RSPA 
believes some of these changes may have merit, they will have to be 
considered in a future rulemaking.
    Proposed paragraph (d) is revised to clarify that each cargo tank 
on a multi-tank cargo tank motor vehicle must have a separate 
nameplate, unless each cargo tank is made by the same manufacturer with 
the same materials, manufactured thickness, and minimum thickness.

Section 178.345-15

    RSPA proposed to add a new paragraph (e) to allow affixing a metal 
certification plate to cargo tanks which do not meet all of the 
applicable specification requirements. This would be indicated by not 
stamping a compliance date on the plate. A commenter pointed out that 
the proposed wording does not specifically require the Registered 
Inspector to stamp the date of compliance on the specification plate 
when the cargo tank is brought into full conformance with the 
specification. RSPA agrees with the commenter and has clarified the 
requirement.
    Another commenter requested a revision to clarify that, for ASME 
tanks, the cargo tank motor vehicle manufacturer must furnish a 
manufacturer's data report to the cargo tank owner as required by the 
ASME Code, in addition to other required documents. The ASME Code 
requires a cargo tank manufacturer to prepare a manufacturer's data 
report for each tank. RSPA agrees with the commenter and has added a 
provision in paragraph (b)(2) specifying that the manufacturer must 
supply the cargo tank owner with a copy of the manufacturer's data 
report, at the time of delivery.

Section 178.346-1

    RSPA proposed to add a new paragraph (d)(9) specifying provisions 
for the use of a single full fillet lap weld joint without plug welds 
for longitudinal seams on the top 25 percent of the cargo tank. For the 
most part, commenters agreed in principal with the proposal; however, 
they recommended that the use of single fillet weld lap joint not be 
limited to the top one-fourth of the cargo tank.
    Several manufacturers stated that they have used single full fillet 
lap welded joints for longitudinal seams on both the top and bottom 
areas of thousands of low-pressure cargo tank motor vehicles. They 
stated their service experience with these joints over many years of 
operations has been very good.
    Advantages cited by the manufacturers for using this type of weld 
include the ability to achieve excellent fit between the shell and head 
flanges, and reduction in the amount of time personnel must work in 
confined spaces. However, because the ASME Code does not recognize this 
joint configuration, it may not be used on ASME certified vessels.
    Industry submitted reports of tensile tests of the typically used 
single full fillet lap joints to RSPA. Test results indicate that 
failure occurs at stress levels of about 70 to 75 percent of the 
ultimate strength of adjacent material. One commenter opposed the use 
of such joints but provided no supporting test data.
    RSPA believes the satisfactory performance of these joints over the 
years serves as a persuasive argument for their continued use on DOT 
406 cargo tank motor vehicles. However, because a major reason for 
establishing the DOT 400-series specifications is enhanced quality 
assurance, the joints may be used only when subject to certain 
conditions. Therefore, new paragraph (d)(9) specifies the conditions 
for use of these joints in longitudinal seams, requirements for 
periodic compliance testing, and design requirements for determining 
weld joint efficiency. In addition, a new paragraph (d)(10) is added to 
clarify that requirements of paragraph UW-9(d), of Section VIII, 
Division 1, ASME Code do not apply.

Section 178.346-2

    Minor editorial changes are made to paragraph (a).

Section 178.346-10

    Valve manufacturers stated that, during prototype testing, they 
have encountered substantial problems in obtaining adequate flow under 
emergency conditions with pressure relief valves designed for the 
comparatively low MAWP levels typical of DOT 406 cargo tank motor 
vehicles. These problems have been resolved for current valves; 
however, the valve manufacturers continue to believe the emergency flow 
capacities, which are permitted to release up to one gallon of lading 
under the dynamic pressure surges characteristic of rollover accidents, 
are still marginal in some cases. Because of the problems encountered 
by valve manufacturers, RSPA will allow an additional year for product 
development and manufacturing start-up. This extension is added in a 
new paragraph (b)(3).
    RSPA proposed to revise paragraph (c)(1) to permit DOT 406 cargo 
tanks to have the same set pressure and test pressure as allowed in 
Sec. 178.345-10(d)(1), and as prescribed for DOT 407 and 412 cargo 
tanks except that the reclosing pressure would remain at no less than 
MAWP. Commenters stated that while the proposed language would be 
helpful in increasing the venting capacity to a limited extent and 
providing a similar difference between opening and closing pressures 
over a range of MAWP values, it would not eliminate the need for 
supplementary venting capacity. Commenters requested that the flow rate 
be determined at a higher pressure, specifically at 125 percent of the 
tank test pressure. This would provide more pressure differential 
across the valve seat and provide higher venting capacities. As 
discussed in the preamble for 178.346-10(b) above, pressure relief 
valve manufacturers reported that they have found it difficult to 
obtain adequate emergency flow capacities in valves designed for DOT 
406 cargo tank motor vehicles.
    Based on comments received, RSPA believes the problem can be 
relieved by implementing two measures. The first measure is to increase 
the tolerance on the valve set pressure to allow the valve to begin 
opening at a lower set pressure and to be fully open at a higher 
pressure. The second measure is to increase the venting capacity rating 
pressure to 125 percent of the tank test pressure, and not greater than 
3 psi above the tank's MAWP. Because the pressure relief valves are 
required to be removed from the cargo tank during periodic pressure 
testing, the tank itself will not be exposed to pressures above its 
normal test pressure [see Sec. 180.407(g)(1)(i)]. This increase in the 
venting capacity rating pressure will still provide a satisfactory 
margin of safety with respect to tank bursting pressure, even in the 
event of exposure to fire. The combined effect of these changes can be 
expected to significantly raise the pressure differential across the 
valve seat, thus increasing flow. Accordingly, both paragraphs (c)(1) 
and paragraph (d)(1) have been revised to include these two measures.

Section 178.346-13

    In the NPRM, RSPA proposed to increase the emergency flow capacity 
of DOT 406 pressure relief valves by raising the test pressure of the 
cargo tank. This was intended to alleviate problems reported by valve 
manufacturers by increasing the differential pressure across the valve 
seat, thus increasing flow. However, commenters requested that RSPA not 
make this change because of the increased danger of deformation of 
heads at pressure levels above 5.0 psig, especially for internal heads 
in which the pressure is applied to the convex side. One commenter 
stated that pressures above 5.0 psig would require increased head 
thickness or bracing, thus increasing the weight of the tank resulting 
in lower payload and higher manufacturing cost.
    As an alternative means of increasing emergency flow, commenters 
suggested that the set pressure and the flow rating pressure of the 
pressure relief valve itself be changed while retaining the existing 
tank test pressure. RSPA agrees with this alternative. Therefore, RSPA 
has revised paragraphs 178.346-10(c)(1) and (d)(1) instead of revising 
the tank test pressure requirements.
    Shortly before publication of the NPRM, TTMA petitioned RSPA to use 
the Environmental Protection Agency (EPA) test for vapor-tightness for 
all DOT 406 cargo tanks. TTMA requested that Method 27 be authorized 
for all DOT 406 cargo tanks, regardless of whether they are: (a) used 
in gasoline delivery, (b) fitted with vapor collection equipment, or 
(c) subject to this test under EPA rules. Method 27, is found in 
appendix A. to 40 CFR Part 60. Section 1.1 of Method 27 is applicable 
for the determination of vapor tightness of a gasoline delivery tank 
which is equipped with vapor collection equipment. Requirements for 
applying the initial pressure-vacuum and test criteria are contained in 
40 CFR Part 60, Subpart XX--Standards of Performance for Bulk Gasoline 
Terminals. In Sec. 60.501, the definition of vapor tight gasoline tank 
truck reads:

    Vapor-tight gasoline tank truck means a gasoline tank truck 
which has demonstrated within the 12 preceding months that its 
product delivery tank will sustain a pressure change of not more 
than 750 pascals (75 mm of water) within 5 minutes after it is 
pressurized to 4,500 pascals (450 mm of water). This capability is 
to be demonstrated using the pressure test procedure specified in 
Reference Method 27.

    It should be noted that 750 pascals = 0.109 psi = 3.0 inches of 
water and 4,500 pascals = 0.653 psi = 18.1 inches of water. Similar 
provisions for benzene are prescribed in 40 CFR Part 60, Subpart BB--
National Emission Standard for Benzene Emissions from Benzene Transfer 
Operations, at Sec. 60.601.
    RSPA authorized this alternative leakage test in the June 12, 1989 
final rule published under HM-183 to relieve burdens of duplicate test 
requirements for cargo tanks intended for use in locations where, based 
on established standards of air quality, EPA has decided that release 
of gasoline vapors constitutes a hazard to the environment. TTMA stated 
that a cargo tank motor vehicle manufacturer may not know the local air 
pollution requirements to which the motor vehicle may be subject. RSPA 
recognizes TTMA's concerns and is permitting this alternative test when 
a cargo tank is equipped with vapor recovery equipment without 
qualification regarding the materials transported. RSPA also has 
revised paragraph (c) and Sec. 180.407(h)(2) to reference appropriate 
acceptance criteria in EPA's regulation contained in 40 CFR 60.

Section 180.403

    Commenters supported the proposal to add a definition for the term 
``replacement of a barrel.'' TTMA recommended that, in the definition 
of ``replacement of a barrel'' the wording ``unused tank'' should be 
clarified to mean a ``new tank.'' RSPA agrees and the word ``new'' is 
added parenthetically after the word ``unused.''
    Commenters also supported the proposal to revise the definition of 
rebarrelling. However, for the reasons contained in the preamble 
discussion for Sec. 180.413 the proposed revision is not being adopted 
in this final rule. A commenter recommended that the definition of 
``repair'' be modified to include the replacement of components such as 
valves, vents and fittings. RSPA believes this suggested change would 
be confusing because a ``repair'' is specifically defined to mean ``any 
welding done to the cargo tank wall to return it to the original 
specification or a later equivalent specification.'' Replacement of 
valves, vents and fittings is considered maintenance. Therefore, the 
current definition is retained.

Section 180.405

    Minor editorial changes are made in subparagraphs (f)(1)(iii) and 
(f)(4) as proposed in the NPRM.
    In paragraph (g)(2), RSPA proposed to clarify that fittings and 
devices mounted on a manhole cover are part of the manhole assembly and 
must meet all performance standards required for the manhole cover. A 
commenter stated that the current requirement is adequate and 
recommended that RSPA not adopt the proposed change. The commenter 
stated that any concern or problem is due to a lack in verifying the 
continued proper securement of these fittings and devices to the 
manhole cover. The commenter said that the annual leakage test and 
inspection requirements in Sec. 180.407 should be sufficient to assure 
that these in-service fittings and devices remain securely mounted and 
properly sealed on in-service manholes. RSPA agrees with the commenter 
and the proposed changes are not adopted in this final rule.
    Another commenter recommended that paragraph (g)(2)(i) be revised 
to add ``month and year'' to the certification marking on manhole 
assemblies. Although RSPA believes that such a requirement may have 
merit, an opportunity should be provided for public comment; therefore, 
it will be considered in a future rulemaking action.
    Paragraph (h) specifies that replacement for any reclosing pressure 
relief valve must be capable of re-seating to a leak-tight condition 
after a pressure surge. Section 180.405(c) authorizes modifying the 
reclosing pressure relief valves of an MC 306 cargo tank by installing 
the dual function pressure relief valves which are required for DOT 406 
cargo tank motor vehicles. Commenters pointed out that this replacement 
could result in an MC 306 cargo tank having lower emergency venting 
capacity than its specification requires; because it is difficult to 
produce a valve that achieves the comparatively high flow rates of the 
MC 306 units, withstands the pressure surges specified in the DOT 406 
specification, and recloses with minimal loss of lading. A reduced flow 
capacity is less likely to be encountered in fitting an MC 307 with a 
DOT 407 valve replacement, and in fitting an MC 312 with a DOT 412 
valve replacement, because of the larger pressure differentials which 
are commonly used in these cargo tanks. Regardless of the equipment 
installed, the venting requirements specified in the particular cargo 
tank specification must be met whenever a pressure relief valve is 
replaced. For this reason, in this final rule, RSPA is authorizing 
replacement of defective MC 306 pressure relief valves with new or 
refurbished MC 306 pressure relief valves until August 31, 1998. After 
this date, any valve replacements must be the surge resistant pressure 
relief valves required for DOT 400-series cargo tanks. This allows 
three years for implementation of this safety approvement.

Section 180.407

    In the table in paragraph (c), chlorine cargo tanks must be leakage 
tested annually. These cargo tanks are also required to be pressure 
tested every two years. Based on a comment, RSPA has extended the 
frequency for conducting the leakage test to two years to coincide with 
the pressure test. Certain minor editorial changes are made in 
paragraph (d)(1)(i) for clarity. Paragraph (e)(1) is revised to clarify 
that when a particular tank design such as a cargo tank with a lining, 
coating or internal baffles, precludes an internal visual inspection, 
the tank must be hydrostatically or pneumatically tested. Paragraph 
(e)(4), which is duplicative with the requirements in paragraph (f)(3), 
is removed as proposed in the NPRM.
    RSPA proposed to revise paragraph (g)(1)(iv), covering the pressure 
test of specification cargo tanks for consistency with the proposed 
changes to Sec. 178.346-10; however, commenters who initially sought 
this change recommended that the proposal be withdrawn and the current 
provisions retained. Therefore, no change is made in this final rule.
    Paragraph (h)(2) is revised to permit the use of the EPA Method 27 
vapor tightness test on any cargo tank fitted with a vapor recovery 
system and used in gasoline or benzene service, as discussed earlier 
under the preamble discussion to Sec. 178.346-13(c)(2). A commenter 
suggested that paragraph (h)(2) require the use of oil or soap to 
detect leaks in cargo tank seams, piping, valves and accessories when 
performing the Method 27 test. RSPA believes that oil or soap can be 
very useful in locating leaks, but that it would be an unnecessary 
burden if required for all Method 27 tests. Accordingly, RSPA has not 
adopted the suggested change.
    Paragraph (i) prescribes that the heads and shell of all unlined 
cargo tanks used for the transportation of materials corrosive to the 
tank must be thickness tested. Consistent with changes made to 
Sec. 178.345-1(1)(2) in this final rule, a new paragraph (i)(4)(x) is 
added to specify that thickness testing must be performed on connecting 
structures of a carbon steel, self-supporting multi-tank cargo tank 
motor vehicle.
    Requirements for continuing qualification and maintenance of cargo 
tank motor vehicles include periodic measurement of the thickness of 
heads and shells. This has focused attention on interpretation of 
specification requirements for minimum thickness, especially of 
specification MC 306, MC 307, MC 312 cargo tanks and their 
predecessors.
    In the specifications for MC 306, MC 307 and MC 312 cargo tanks 
constructed of steel, minimum thickness requirements for heads and 
shells were expressed in terms of U. S. Standard Gauges for sheet 
material or, for some MC 312 units where plate material was specified, 
in terms of fractions of an inch. These data were found at Table I and 
Table II in specifications for each of the respective types. Although 
not explicitly stated in the regulatory text, the tabulated values were 
the minimum nominal sheet and plate sizes permitted for these cargo 
tanks. For aluminum, values in Table I and Table II were the minimum 
nominal thickness expressed in decimals. The tolerances on mill 
thickness and the minimum thickness after forming were not covered. 
Although major steel purchase orders and steel mill production controls 
for sheet stock and thin plate are based on specific thicknesses and 
tolerances rather than on standard gauges, manufacturing tolerances 
have been established by the American Society for Testing and Materials 
(ASTM) for standard gauges and plate. For example, ASTM A480/A480M 
provides general specifications for stainless steels and heat-resisting 
steel plate, sheet and strip; Tables A1.2 and A1.17 in this 
specification are of special interest to manufacturers of DOT 
specification cargo tanks. For MC 307 and MC 312 cargo tanks which were 
required to be designed and constructed in accordance with the ASME 
Code, minimum mill undertolerances are set forth in Section VIII, 
Division 1 at UG-16(c). The ASME values are more restrictive than those 
of ASTM A480/A480M.
    In January 1991, the National Tank Truck Carriers, Inc. (NTTC) 
published a revision to their ``Cargo Tank Maintenance Manual'' which 
included a table of minimum thicknesses for U.S. steel gauges ranging 
from 3 through 30. The accompanying narrative stated that the basic 
information was ``provided by DOT.'' A table, contained in 
Sec. 173.24(c)(2) of the 1990 edition of the HMR was cited for gauges 
12 through 30 with extrapolation being used to complete the other 
gauges. The values presented in that table were intended for relatively 
severe cold-working operations such as those experienced in forming the 
top and bottom chimes of steel drums, not for cargo tank construction. 
However, since adopting 49 CFR 180 Subpart E--Qualification and 
Maintenance of Cargo Tanks, the values published in the NTTC manual 
have been used for thickness testing as required by Sec. 180.407(i). In 
the NPRM, RSPA proposed to add a new paragraph (i)(5) containing a 
minimum thickness table for steel and aluminum for the sizes of sheet 
and plate which have been authorized for MC 300, MC 301, MC 302, MC 
303, MC 304, MC 305, MC 306, MC 307, MC 310, MC 311, and MC 312 heads 
and shells. The way in which minimum thickness has been set forth over 
the years has varied. For example, steel thicknesses generally have 
been expressed in terms of U.S. Standard Gauge (USSG), but, in the case 
of the MC 303 specification, both USSG values and decimal values were 
used. Thickness values for aluminum more often have been expressed in 
decimals. However, in the case of the MC 302 specification, both USSG 
values and decimal values were tabulated; and in the case of the MC 304 
specification, the values for aluminum were required to be calculated 
by multiplying the USSG values listed for mild steel by a factor of 
1.44.
    TTMA suggested several changes to the table for clarity. TTMA also 
recommended that the table be divided into two separate tables: one for 
steel and one for aluminum. RSPA agrees with TTMA's recommendation. 
Therefore, in this final rule, current paragraphs (i)(5) through (1)(7) 
are redesignated as paragraphs (i)(6) through (i)(8), and a new 
paragraph (i)(5) containing two minimum thickness tables has been 
added. The tables include all thicknesses found in the eleven 
specifications cited above, plus USSG number 7 which has been used by a 
number of manufacturers. For steel, nominal thicknesses range from USSG 
number 19 to 3/8'' plate; for aluminum, nominal thicknesses range from 
0.078'' to 0.540''.

Section 180.413

    RSPA proposed to revise requirements on the repair, modification, 
stretching or rebarrelling of cargo tanks. A commenter requested a 
revision to the record requirements contained in proposed paragraph (b) 
to require that the National Board ``R-1'' report be completed for all 
repairs on ASME Code stamped cargo tanks. The commenter stated that 
completing the document will ensure that the repair and method of 
repair conforms to the National Board Inspection Code and is approved 
by an Authorized Inspector. RSPA believes this revision is unnecessary 
because Sec. 180.413 requires that any repair or modification involving 
welding on the tank head must be certified by a Registered Inspector, 
and that any repair or modification to an ASME Code ``U'' stamped cargo 
tank must be in accordance with the National Board Inspection Code. The 
National Board requires the use of the ``R-1'' forms for repairs and 
modifications. Therefore, this commenter's recommendation is not 
adopted in this final rule.
    RSPA proposed to require that any repair, modification, stretching 
or rebarrelling of an ASME Code-stamped cargo tank must be performed by 
a repair facility holding a National Board ``R'' stamp. The National 
Board allows a facility other than a National Board ``R'' stamp holder 
to make repairs and modifications to ASME Code cargo tanks when 
authorized within a governmental jurisdiction. Jurisdictional 
authorization is only recognized within state boundaries where the 
repair facility is located. Therefore, because most cargo tank motor 
vehicles are operated in interstate commerce, RSPA has adopted the 
proposal requiring repairs on DOT specification cargo tanks certified 
to the ASME Code to be performed only by a facility holding a valid 
``R'' stamp.
    Based on a letter from TTMA stating that the regulations provide no 
distinction between a ``100 percent rebarrel'' and the manufacture of a 
new cargo tank, RSPA proposed to clarify the rebarrelling requirements 
and to differentiate between ``rebarrelling a cargo tank'' and 
``manufacturing a cargo tank''. It was never RSPA's intent to imply 
that a repair facility holding only a National Board ``R'' stamp would 
be allowed to manufacture a new cargo tank or to perform a ``100 
percent rebarrel'' of a cargo tank. Such work can be performed only by 
a manufacturer who is registered with DOT and holds an ASME ``U'' 
stamp. RSPA proposed adding a provision disallowing a repair facility 
from replacing an entire cargo tank by performing a ``100 percent 
rebarrel.''
    However, based on comments received in the proposed clarification, 
the reference to a ``100 percent rebarrelled cargo tank'' has also 
caused confusion. Therefore, the proposed change is not adopted in this 
final rule, but RSPA will seek to clarify this provision in a future 
rulemaking.
    CGA urged RSPA to add a new paragraph (e)(3)(v) specifying that 
modifications of MC 338 cargo tanks must conform to the specification 
in effect at the time of manufacture or at the time of modification. 
CGA pointed out that many cryogenic cargo tanks were operating under 
DOT exemption prior to adoption of the MC 338 cargo tank specification. 
Some of these units do not conform to the design criteria in 
Secs. 178.338-3 and 178.338-10. CGA stated that engineering and 
manufacturing costs to upgrade these cargo tanks to this new design 
criteria would be too restrictive. Yet, CGA also stated that ``to 
encourage continuous modification and improvement, modifications to MC 
338 cargo tanks must be performed in accordance with the specifications 
in effect at the time of manufacture or at the time of modification.''
    Proposed Sec. 180.413 provides for a cargo tank to be modified in 
accordance with a current specification in effect at the time the work 
is done. For example, a feature on an MC 305 cargo tank may be modified 
in accordance with the MC 306 specification until August 31, 1995, and 
after that date in accordance with the DOT 406 specification; an MC 330 
cargo tank may be modified in accordance with the MC 331 specification. 
Similarly, a cargo tank authorized under an exemption issued before 
October 1, 1984 for transportation of a cryogenic liquid must be marked 
as a ``DOT MC 338'' cargo tank in accordance with Sec. 180.405(d). The 
only cryogenic cargo tank specification is the MC 338. Thus, no feature 
of an MC 338 cryogenic cargo tank can be modified in accordance with 
any other specification. However, an MC 338 cryogenic cargo tank may be 
repaired in accordance with either its original design specified in the 
exemption under which it was manufactured or the MC 338 specification 
requirements in effect at the time of the repair. Therefore, CGA's 
suggested change is not adopted in this final rule.
    CGA recommended a revision to paragraph (e)(6) to clarify that a 
cargo tank manufacturer who welds attachments and appurtenances which 
have no affect on the structural integrity or lading retention 
capability of a tank is not required to have a National Board ``R'' or 
ASME ``U'' stamp. CGA also suggested a revision to paragraph (e)(7) to 
clarify that mounting specifications should be governed by welding to 
the cargo tank ``shell and head'' rather than the cargo tank ``wall''. 
RSPA agrees and paragraphs (e)(6) and (e)(7) are revised for clarity.

IV. Docket HM-183D

    On September 3, 1993, RSPA published an interim final rule that 
amended requirements concerning the registration of Registered 
Inspectors and Design Certifying Engineers for certification of cargo 
tank motor vehicles. RSPA extended the closing of the registration 
period from December 31, 1991 to December 31, 1995. This action was in 
response to a petition for rulemaking, P-1167, filed by NTTC. RSPA 
stated in the rule that although an opportunity for public comment had 
not been provided, RSPA was seeking public comment to the action. RSPA 
further stated that any comments received would be addressed along with 
comments received to the NPRM under Docket HM-183C. The effective date 
of this rule was September 3, 1993. The comment period closed on 
October 13, 1993; RSPA received no comments in regard to this action. 
Therefore, that extension remains in effect.

V. Rulemaking Analyses and Notices

1. Executive Order 12866 and DOT Regulatory Policies and Procedures

    This final rule is not considered a significant regulatory action 
under section 3(f) of Executive Order 12866 and was not reviewed by the 
Office of Management and Budget. The rule is not considered significant 
under the Regulatory policies and Procedures of the Department of 
Transportation (44 FR 11034). A regulatory evaluation is available for 
review in the docket.

2. Executive Order 12612

    This final rule has been analyzed in accordance with the principles 
and criteria contained in Executive Order 12612 (``Federalism''). 
Federal law expressly preempts State, local, and Indian tribe 
requirements applicable to the transportation of hazardous material 
that cover certain subjects and are not ``substantively the same'' as 
the Federal requirements. 49 U.S.C. 5125(b)(1). These covered subjects 
are:
    (A) the designation, description, and classification of hazardous 
material;
    (B) the packing, repacking, handling, labeling, marking, and 
placarding of hazardous material;
    (C) the preparation, execution, and use of shipping documents 
related to hazardous material and requirements respecting the number, 
contents, and placement of those documents;
    (D) the written notification, recording, and reporting of the 
unintentional release in transportation of hazardous material; or
    (E) the design, manufacturing, fabricating, marking, maintenance, 
reconditioning, repairing, or testing of a packaging or a container 
which is represented, marked, certified, or sold as qualified for use 
in transporting hazardous material.
    This final rule addresses the design, manufacturing, repairing, and 
other requirements for packages represented as qualified for use in the 
transportation of hazardous material. Therefore, this final rule 
preempts State, local, or Indian tribe requirements that are not 
``substantively the same'' as Federal requirements on these subjects. 
Section 5125(b)(2) of Title 49 U.S.C. provides that when DOT issues a 
regulation concerning any of the covered subjects after November 16, 
1990, DOT must determine and publish in the Federal Register the 
effective date of Federal preemption. The effective date may not be 
earlier than the 90th day following the date of issuance of the final 
rule and no later than two years after the date of issuance. RSPA has 
determined that the effective date of Federal preemption of this final 
rule will be 90 days after publication in the Federal Register.
    Because RSPA lacks discretion in this area, preparation of a 
federalism assessment is not warranted.

3. Regulatory Flexibility Act

    I certify that this final rule will not have a significant economic 
impact on a substantial number of small entities. There are no direct 
or indirect adverse economic impacts for small units of government, 
businesses, or other organizations.

4. Paperwork Reduction Act

    This amendment imposes no changes to the information collection and 
recordkeeping requirements contained in the June 12, 1989 final rule, 
which were approved by the Office of Management and Budget (OMB) under 
the provisions of 44 U.S.C. chapter 35 and assigned control number 
2137-0014.

5. Regulation Identifier Number (RIN)

    A regulation identifier number (RIN) is assigned to each regulatory 
action listed in the Unified Agenda of Federal Regulations. The 
Regulatory Information Service Center publishes the Unified Agenda in 
April and October of each year. The RIN number contained in the heading 
of this document can be used to cross-reference this action with the 
Unified Agenda.

List of Subjects

49 CFR Part 171

    Exports, Hazardous materials transportation, Hazardous waste, 
Imports, Incorporation by reference, Reporting and recordkeeping 
requirements.

49 CFR Part 173

    Hazardous materials transportation, Packaging and containers, 
Radioactive materials, Reporting and recordkeeping requirements, 
Uranium.

49 CFR Part 178

    Hazardous materials transportation, Motor vehicles safety, 
Packaging and containers, Reporting and recordkeeping requirements.

49 CFR Part 180

    Hazardous materials transportation, Motor carriers, Motor vehicle 
safety, Packaging and containers, Reporting and recordkeeping 
requirements.
    In consideration of the foregoing, title 49, chapter I of the Code 
of Federal Regulations, is amended as set forth below:

PART 171--GENERAL INFORMATION, REGULATIONS, AND DEFINITIONS

    1. The authority citation for part 171 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127; 49 CFR 1.53.

    2. In Sec. 171.7, in paragraph (a)(3) table, the first entry for 
the ASME Code and the entry for the National Board Inspection Code are 
revised to read as follows:


Sec. 171.7  Reference material.

    (a) * * *
    (3) Table of material incorporated by reference. * * * 

----------------------------------------------------------------------------------------------------------------
              Source and name of material                                    49 CFR reference                   
----------------------------------------------------------------------------------------------------------------
                                                                                                                
                                                  * * * * * * *                                                 
American Society of Mechanical Engineers:                                                                       
                                                                                                                
    ASME Code, Sections II (Parts A and B), V, VIII      173.32; 173.306; 173.315; 173.318; 173.420; 178.245;   
     (Division 1), and IX of 1992 Edition of American     178.255; 178.270; 178.271; 178.272; 178.337; 178.338; 
     Society of Mechanical Engineers Boiler and           178.345; 178.346; 178.347; 178.348; 179.400; 180.407; 
     Pressure Vessel Code and Addenda through December    180.417                                               
     31, 1993.                                                                                                  
                                                                                                                
National Board of Boiler and Pressure Vessel                                                                    
 Inspectors:                                                                                                    
                                                                                                                
                                                                                                                
                                                  * * * * * * *                                                 
National Board Inspection Code, A Manual for Boiler and  180.413                                                
 Pressure Vessel Inspectors, NB-23, 1992 Edition                                                                
                                                                                                                
                                                                                                                
                                                  * * * * * * *                                                 
----------------------------------------------------------------------------------------------------------------

* * * * *

PART 173--SHIPPERS--GENERAL REQUIREMENTS FOR SHIPMENTS AND 
PACKAGINGS

    3. The authority citation for part 173 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    4. In Sec. 173.33, a new paragraph (h) is added to read as follows:


Sec. 173.33 Hazardous materials in cargo tank motor vehicles.

* * * * *
    (h) Each liquid or vapor discharge opening in an MC 330 or MC 331 
cargo tank and each liquid filling and liquid discharge line in an MC 
338 cargo tank must be provided with a remotely controlled internal 
self-closing stop valve, except when an MC 330 or MC 331 cargo tank is 
marked and used exclusively to transport carbon dioxide, or except when 
an MC 338 is used to transport argon, carbon dioxide, helium, krypton, 
neon, nitrogen, and xenon. However, if the cargo tank motor vehicle was 
certified before January 1, 1995, this requirement is applicable only 
when an MC 330 or MC 331 cargo tank is used to transport a flammable 
liquid, flammable gas, hydrogen chloride (refrigerated liquid), or 
anhydrous ammonia; or when an MC 338 cargo tank is used to transport 
flammable ladings.


Sec. 173.33  [Amended]

    5. In addition, in Sec. 173.33, in paragraph (d)(3), a second 
sentence is added at the end of the text preceding the table to read 
``The venting capacity requirements of the original DOT cargo tank 
specification must be met whenever a pressure relief valve is 
modified.''.


Sec. 173.225  [Amended]

    6. In Sec. 173.225, in paragraph (e)(2), the phrase ``MC 310, MC 
311, MC 312 and DOT 412'' is revised to read ``MC 307, MC 310, MC 311, 
MC 312, DOT 407, and DOT 412''.
    7. In Sec. 173.315, paragraph (o)(1) and the first sentence in 
paragraph (o)(2) are revised to read as follows:


Sec. 173.315  Compressed gases in cargo tanks and portable tanks.

* * * * *
    (o) * * *
    (1) Any hose, piping, or tubing used for loading or unloading that 
is mounted or carried on the motor vehicle may not be attached to any 
valve and must be capped at all ends to prevent the entry of moisture, 
except at the time of loading or unloading. Except at the time of 
loading and unloading, the pipe connection of each angle valve must be 
closed with a screw plug which is chained or otherwise fastened to 
prevent misplacement.
    (2) Each chlorine cargo tank angle valve must be tested to be leak 
free at not less than 225 psig using dry air or inert gas before 
installation and thereafter every 2 years when performing the required 
periodic retest in Sec. 180.407(c) of this subchapter. * * *
* * * * *

PART 178--SPECIFICATIONS FOR PACKAGINGS

    8. The authority citation for part 178 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    9. In Sec. 178.337-1, paragraph (e)(2) is amended by revising the 
last sentence to read as follows:


Sec. 178.337-1  General requirements.

* * * * *
    (e)* * *
    (2)* * *Insulating material used on tanks for chlorine must be 
corkboard or polyurethane foam, with a minimum thickness of 4 inches, 
or 2 inches minimum thickness of ceramic fiber/fiberglass of 4 pounds 
per cubic foot minimum density covered by 2 inches minimum thickness of 
fiber.
* * * * *


Sec. 178.337-1  [Amended]

    10. In addition, in Sec. 178.337-1, the following changes are made:
    a. In paragraph (a)(3), the reference ``173.33(i)'' is revised to 
read ``178.337-1(e)(2)'' and the reference ``173.315(a) Table Note 11'' 
is revised to read ``173.315(a) Table''.
    b. In paragraph (e)(1), the reference ``173.315(a) Table, Note 11'' 
is revised to read ``173.315(a) Table''.


Sec. 178.337-9  [Amended]

    11. In Sec. 178.337-9, paragraph (b)(7)(i) is removed, and 
paragraphs (b)(7)(ii) and (b)(7)(iii) are redesignated as paragraphs 
(b)(7)(i) and (b)(7)(ii), respectively.
    12. In Sec. 178.337-11, paragraph (a)(2) introductory text is 
revised to read as follows:


Sec. 178.337-11  Emergency discharge control.

    (a)* * *
    (2) Except for a cargo tank marked ``For carbon dioxide only'', 
each liquid or vapor discharge opening in a cargo tank must be equipped 
with a remotely controlled internal self-closing stop valve. This 
requirement does not apply to a cargo tank motor vehicle certified 
before January 1, 1995, unless intended for use to transport a 
flammable liquid, flammable gas, hydrogen chloride, refrigerated 
liquid, or anhydrous ammonia. For cargo tanks intended for use in 
chlorine service, see paragraph (a)(4) of this section.
* * * * *
    13. In Sec. 178.338-9, paragraph (c)(2) is revised to read as 
follows:


Sec. 178.338-9  Holding time.

* * * * *
    (c)* * *
    (2) Same design. The term ``same design'' as used in this section 
means cargo tanks made to the same design type. See Sec. 178.320(a)(3) 
for definition of ``design type''.
* * * * *
    14. In Sec. 178.338-11, in the introductory text in paragraph (c), 
the first sentence is removed and two new sentences are added to read 
as follows:


Sec. 178.338-11  Discharge control devices.

* * * * *
    (c) Except for a cargo tank used to transport the following 
refrigerated liquids: argon, carbon dioxide, helium, krypton, neon, 
nitrogen, and xenon; each liquid filling and liquid discharge line must 
be provided with a remotely controlled internal self-closing stop 
valve. This requirement does not apply to a cargo tank motor vehicle 
certified before January 1, 1995, unless intended for use to transport 
flammable ladings.* * *
* * * * *
    15. In Sec. 178.345-1, in paragraph (c), definitions for ``Extreme 
dynamic loading'' and ``Normal operating loading'' are added, in 
appropriate alphabetical order and paragraph (i)(2) is revised to read 
as follows:


Sec. 178.345-1  General requirements.

* * * * *
    (c)* * *
* * * * *
    Extreme dynamic loading means the maximum single-acting loading a 
cargo tank may experience during its expected life, excluding accident 
loadings.
* * * * *
    Normal operating loading means the loading a cargo tank may be 
expected to experience routinely in operation.
* * * * *
    (i)* * *
    (2) The strength of the connecting structure joining multiple cargo 
tanks in a cargo tank motor vehicle must meet the structural design 
requirements in Sec. 178.345-3. Any void within the connecting 
structure must be vented to the atmosphere and have a drain located on 
the bottom centerline. Each drain must be accessible and must be kept 
open at all times. The drain in any void within the connecting 
structure of a carbon steel, self-supporting cargo tank may be either a 
single drain of at least 1.0 inch diameter, or two or more drains of at 
least 0.5 inch diameter, 6.0 inches apart, one of which is located on 
the bottom centerline.
* * * * *
    16. In Sec. 178.345-3, paragraphs (b) and (c) are revised to read 
as follows:


Sec. 178.345-3  Structural integrity.

* * * * *
    (b) ASME Code design and construction. The static design and 
construction of each cargo tank must be in accordance with Section 
VIII, Division 1 of the ASME Code. The tank design must include 
calculation of stresses generated by the MAWP, the weight of the 
lading, the weight of structures supported by the cargo tank wall and 
the effect of temperature gradients resulting from lading and ambient 
temperature extremes. When dissimilar materials are used, their thermal 
coefficients must be used in the calculation of thermal stresses.
    (1) Stress concentrations in tension, bending and torsion which 
occur at pads, cradles, or other supports must be considered in 
accordance with Appendix G of Section VIII, Division 1 of the ASME 
Code.
    (2) Longitudinal compressive buckling stress for ASME certified 
vessels must be calculated using paragraph UG-23(b), Section VIII, 
Division 1 of the ASME Code. For cargo tanks not required to be 
certified in accordance with the ASME Code, compressive buckling stress 
may be calculated using alternative analysis methods which are accurate 
and verifiable. When alternative methods are used calculations must 
include both the static loads described in this paragraph and the 
dynamic loads described in paragraph (c) of this section.
    (c) Shell design. Shell stresses resulting from static or dynamic 
loadings, or combinations thereof, are not uniform throughout the cargo 
tank motor vehicle. The vertical, longitudinal, and lateral normal 
operating loadings can occur simultaneously and must be combined. The 
vertical, longitudinal and lateral extreme dynamic loadings occur 
separately and need not be combined.
    (1) Normal operating loadings. The following procedure addresses 
stress in the tank shell resulting from normal operating loadings. The 
effective stress (the maximum principal stress at any point) must be 
determined by the following formula:

S = 0.5(Sy + Sx)  [0.25(Sy-Sx)\2\ + 
SS2]0.5
Where:

    (i) S = effective stress at any given point under the combination 
of static and normal operating loadings that can occur at the same 
time, in psi.
    (ii) Sy = circumferential stress generated by the MAWP and 
external pressure, when applicable, plus static head, in psi.
    (iii) Sx = The following net longitudinal stress generated by 
the following static and normal operating loading conditions, in psi:
    (A) The longitudinal stresses resulting from the MAWP and external 
pressure, when applicable, plus static head, in combination with the 
bending stress generated by the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall;
    (B) The tensile or compressive stress resulting from normal 
operating longitudinal acceleration or deceleration. In each case, the 
forces applied must be 0.35 times the vertical reaction at the 
suspension assembly, applied at the road surface, and as transmitted to 
the cargo tank wall through the suspension assembly of a trailer during 
deceleration; or the horizontal pivot of the tractor or converter dolly 
fifth wheel, or the drawbar hinge on the fixed dolly during 
acceleration; or anchoring and support members of a truck during 
acceleration and deceleration, as applicable. The vertical reaction 
must be calculated based on the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall. The following loadings must be included:
    (1) The axial load generated by a decelerative force;
    (2) The bending moment generated by a decelerative force;
    (3) The axial load generated by an accelerative force; and
    (4) The bending moment generated by an accelerative force; and
    (C) The tensile or compressive stress generated by the bending 
moment resulting from normal operating vertical accelerative force 
equal to 0.35 times the vertical reaction at the suspension assembly of 
a trailer; or the horizontal pivot of the upper coupler (fifth wheel) 
or turntable; or anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall.
    (iv) SS = The following shear stresses generated by the 
following static and normal operating loading conditions, in psi:
    (A) The static shear stress resulting from the vertical reaction at 
the suspension assembly of a trailer, and the horizontal pivot of the 
upper coupler (fifth wheel) or turntable; or anchoring and support 
members of a truck, as applicable. The vertical reaction must be 
calculated based on the static weight of the fully loaded cargo tank, 
all structural elements, equipment and appurtenances supported by the 
cargo tank wall;
    (B) The vertical shear stress generated by a normal operating 
accelerative force equal to 0.35 times the vertical reaction at the 
suspension assembly of a trailer; or the horizontal pivot of the upper 
coupler (fifth wheel) or turntable; or anchoring and support members of 
a truck, as applicable. The vertical reaction must be calculated based 
on the static weight of the fully loaded cargo tank, all structural 
elements, equipment and appurtenances supported by the cargo tank wall;
    (C) The lateral shear stress generated by a normal operating 
lateral accelerative force equal to 0.2 times the vertical reaction at 
each suspension assembly of a trailer, applied at the road surface, and 
as transmitted to the cargo tank wall through the suspension assembly 
of a trailer, and the horizontal pivot of the upper coupler (fifth 
wheel) or turntable; or anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall; and
    (D) The torsional shear stress generated by the same lateral forces 
as described in paragraph (c)(1)(iv)(C) of this section.
    (2) Extreme dynamic loadings. The following procedure addresses 
stress in the tank shell resulting from extreme dynamic loadings. The 
effective stress (the maximum principal stress at any point) must be 
determined by the following formula:

S = 0.5(Sy + Sx)  [0.25(Sy - Sx)\2\ + 
SS\2\]0.5

Where:
    (i) S = effective stress at any given point under a combination of 
static and extreme dynamic loadings that can occur at the same time, in 
psi.
    (ii) Sy = circumferential stress generated by MAWP and 
external pressure, when applicable, plus static head, in psi.
    (iii) Sx = the following net longitudinal stress generated by 
the following static and extreme dynamic loading conditions, in psi:
    (A) The longitudinal stresses resulting from the MAWP and external 
pressure, when applicable, plus static head, in combination with the 
bending stress generated by the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the tank wall;
    (B) The tensile or compressive stress resulting from extreme 
longitudinal acceleration or deceleration. In each case the forces 
applied must be 0.7 times the vertical reaction at the suspension 
assembly, applied at the road surface, and as transmitted to the cargo 
tank wall through the suspension assembly of a trailer during 
deceleration; or the horizontal pivot of the tractor or converter dolly 
fifth wheel, or the drawbar hinge on the fixed dolly during 
acceleration; or the anchoring and support members of a truck during 
acceleration and deceleration, as applicable. The vertical reaction 
must be calculated based on the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall. The following loadings must be included:
    (1) The axial load generated by a decelerative force;
    (2) The bending moment generated by a decelerative force;
    (3) The axial load generated by an accelerative force; and
    (4) The bending moment generated by an accelerative force; and
    (C) The tensile or compressive stress generated by the bending 
moment resulting from an extreme vertical accelerative force equal to 
0.7 times the vertical reaction at the suspension assembly of a 
trailer, and the horizontal pivot of the upper coupler (fifth wheel) or 
turntable; or the anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall.
    (iv) SS = The following shear stresses generated by static and 
extreme dynamic loading conditions, in psi:
    (A) The static shear stress resulting from the vertical reaction at 
the suspension assembly of a trailer, and the horizontal pivot of the 
upper coupler (fifth wheel) or turntable; or anchoring and support 
members of a truck, as applicable. The vertical reaction must be 
calculated based on the static weight of the fully loaded cargo tank, 
all structural elements, equipment and appurtenances supported by the 
cargo tank wall;
    (B) The vertical shear stress generated by an extreme vertical 
accelerative force equal to 0.7 times the vertical reaction at the 
suspension assembly of a trailer, and the horizontal pivot of the upper 
coupler (fifth wheel) or turntable; or anchoring and support members of 
a truck, as applicable. The vertical reaction must be calculated based 
on the static weight of the fully loaded cargo tank, all structural 
elements, equipment and appurtenances supported by the cargo tank wall;
    (C) The lateral shear stress generated by an extreme lateral 
accelerative force equal to 0.4 times the vertical reaction at the 
suspension assembly of a trailer, applied at the road surface, and as 
transmitted to the cargo tank wall through the suspension assembly of a 
trailer, and the horizontal pivot of the upper coupler (fifth wheel) or 
turntable; or anchoring and support members of a truck, as applicable. 
The vertical reaction must be calculated based on the static weight of 
the fully loaded cargo tank, all structural elements, equipment and 
appurtenances supported by the cargo tank wall; and
    (D) The torsional shear stress generated by the same lateral forces 
as described in paragraph (c)(2)(iv)(C) of this section.
* * * * *


Sec. 178.345-3  [Amended]

    17. In addition, in Sec. 178.345-3, the following changes are made:
    a. In paragraph (a)(1), the phrase at the beginning of the sentence 
``Except as provided in paragraph (d) of this section, the'' is removed 
and replaced with the word ``The''.
    b. In paragraph (a)(3), the wording ``paragraphs (b), (c), and (d) 
of this section'' is revised to read ``paragraphs (b) and (c) of this 
section'' each place it appears.
    c. Paragraph (d) is removed.
    d. Paragraphs (e) through (g) are redesignated as paragraphs (d) 
through (f), and in redesignated paragraph (d) the wording ``cargo tank 
wall'' is revised to read ``cargo tank shell and heads''.
    18. In Sec. 178.345-5, a new paragraph (f) is added to read as 
follows:


Sec. 178.345-5  Manhole assemblies.

* * * * *
    (f) All fittings and devices mounted on a manhole cover, coming in 
contact with the lading, must withstand the same static internal fluid 
pressure and contain the same permanent compliance markings as that 
required for the manhole cover. The fitting or device manufacturer 
shall verify compliance using the same test procedure and frequency of 
testing as specified in Sec. 178.345-5(b).


Sec. 178.345-6  [Amended]

    19. In Sec. 178.345-6, in paragraphs (a) and (b), the second 
sentence of each paragraph is revised to read ``The design calculations 
of the support elements must include the stresses indicated in 
Sec. 178.345-3(b) and as generated by the loads described in 
Sec. 178.345-3(c).''.
    20. In Sec. 178.345-8, paragraphs (a)(3), (b) introductory text, 
(b)(1), (c) introductory text, (c)(1), and (d)(3) are revised; and a 
new paragraph (e) is added to read as follows:


Sec. 178.345-8  Accident damage protection.

    (a) * * *
    (3) Accident damage protection devices attached to the wall of a 
cargo tank must be able to withstand or deflect away from the cargo 
tank the loads specified in this section. They must be designed, 
constructed and installed so as to maximize the distribution of loads 
to the tank wall and to minimize the possibility of adversely affecting 
the lading retention integrity of the cargo tank. Accident induced 
stresses resulting from the appropriate accident damage protection 
device requirements in combination with the stresses from the tank 
operating at the MAWP may not result in a tank wall stress greater than 
the ultimate strength of the material of construction using a safety 
factor of 1.3. Deformation of the protection device is acceptable 
provided the devices being protected are not damaged when loads 
specified in this section are applied.
* * * * *
    (b) Each outlet, projection or piping located in the lower \1/3\ of 
the tank circumference (or cross section perimeter for non-circular 
tanks) that could be damaged in an accident that may result in the loss 
of lading must be protected by a bottom damage protection device, 
except as provided by paragraph (a)(1) of this section and 
Sec. 173.33(e) of this subchapter. Outlets, projections and piping may 
be grouped or clustered together and protected by a single protection 
device.
    (1) Any bottom damage protection device must be able to withstand a 
force of 155,000 pounds (based on the ultimate strength of the 
material) from the front, side, or rear, uniformly distributed over 
each surface of the device, over an area not to exceed 6 square feet, 
and a width not to exceed 6 feet. Suspension components and structural 
mounting members may be used to provide all, or part, of this 
protection. The device must extend no less than 6 inches beyond any 
component that may contain lading in transit.
* * * * *
    (c) Each closure for openings, including but not limited to the 
manhole, filling or inspection openings, and each valve, fitting, 
pressure relief device, vapor recovery stop valve or lading retaining 
fitting located in the upper \2/3\ of a cargo tank circumference (or 
cross section perimeter for non-circular tanks) must be protected by 
being located within or between adjacent rollover damage protection 
devices, or by being 125 percent of the strength that would be provided 
by the otherwise required damage protection device.
    (1) A rollover damage protection device on a cargo tank motor 
vehicle must be designed and installed to withstand loads equal to 
twice the weight of the loaded cargo tank motor vehicle applied as 
follows: normal to the tank shell (perpendicular to the tank surface); 
and tangential (perpendicular to the normal load) from any direction. 
The stresses shall not exceed the ultimate strength of the material of 
construction. These design loads may be considered to be uniformly 
distributed and independently applied. If more than one rollover 
protection device is used, each device must be capable of carrying its 
proportionate share of the required loads and in each case at least 
one-fourth the total tangential load. The design must be proven capable 
of carrying the required loads by calculations, tests or a combination 
of tests and calculations.
* * * * *
    (d) * * *
    (3) The structure of the rear-end protection device and its 
attachment to the vehicle must be designed to satisfy the conditions 
specified in paragraph (d)(1) of this section when subjected to an 
impact of the cargo tank motor vehicle at rated payload, at a 
deceleration of 2 ``g''. Such impact must be considered as being 
uniformly applied in the horizontal plane at an angle of 10 degrees or 
less to the longitudinal axis of the vehicle.
    (e) Longitudinal deceleration protection. In order to account for 
stresses due to longitudinal impact in an accident, the tank shell and 
heads must be able to withstand the load resulting from the design 
pressure in combination with the dynamic pressure resulting from a 
longitudinal deceleration of 2 ``g''. For this loading condition, the 
allowable stress value used may not exceed the ultimate strength of the 
material of construction using a safety factor of 1.3. Performance 
testing, analytical methods, or a combination thereof, may be used to 
prove this capability provided the methods are accurate and verifiable. 
For cargo tanks with internal baffles, the decelerative force may be 
reduced by 0.25 ``g'' for each baffle assembly, but in no case may the 
total reduction in decelerative force exceed 1.0 ``g''.
    21. In 178.345-10, paragraphs (b)(3)(i) and (ii) are revised to 
read as follows:


Sec. 178.345-10  Pressure relief.

* * * * *
    (b) * * *
    (3) * * *
    (i) Each pressure relief device must be able to withstand dynamic 
pressure surge reaching 30 psig above the design set pressure and 
sustained above the set pressure for at least 60 milliseconds with a 
total volume of liquid released not exceeding one gallon before the 
relief device recloses to a leak-tight condition. This requirement must 
be met regardless of vehicle orientation. This capability must be 
demonstrated by testing. An acceptable test procedure is outlined in 
TTMA RP No. 81--``Performance of Spring Loaded Pressure Relief Valves 
on MC 306, MC 307, and MC 312 Tanks,'' May 24, 1989 edition.
    (ii) After August 31, 1995, each pressure relief device must be 
able to withstand a dynamic pressure surge reaching 30 psig above the 
design set pressure and sustained above the design set pressure for at 
least 60 milliseconds with a total volume of liquid released not 
exceeding one liter before the relief valve recloses to a leak-tight 
condition. This requirement must be met regardless of vehicle 
orientation. This capability must be demonstrated by testing. TTMA RP 
No. 81, cited in paragraph (b)(3)(i) of this section, is an acceptable 
test procedure.
* * * * *


Sec. 178.345-13  [Amended]

    22. In Sec. 178.345-13, a heading is added to paragraph (c) to read 
``Leakage test.''.


Sec. 178.345-14  [Amended]

    23. In Sec. 178.345-14, in paragraph (d), the following changes are 
made:
    a. The paragraph heading ``Multi-cargo tank cargo tank motor 
vehicle'' is revised to read ``Multi-tank cargo tank motor vehicle''.
    b. At the end of the second sentence, the phrase ``unless all of 
the cargo tanks are identical'' is revised to read ``unless all cargo 
tanks are made by the same manufacturer with the same materials, 
manufactured thickness, minimum thickness and to the same 
specification''.
    24. In Sec. 178.345-15, a sentence is added in the beginning of 
paragraph (b)(2) and a new paragraph (e) is added to read as follows:


Sec. 178.345-15  Certification.

* * * * *
    (b) * * *
    (2) For each ASME tank, a tank manufacturer's data report as 
required by the ASME Code. * * *
* * * * *
    (e) Specification shortages. If a cargo tank is manufactured which 
does not meet all applicable specification requirements, thereby 
requiring subsequent manufacturing involving the installation of 
additional components, parts, appurtenances or accessories, the cargo 
tank manufacturer may affix the name plate and specification plate, as 
required by Sec. 178.345-14 (b) and (c), without the original date of 
certification stamped on the specification plate. The manufacturer 
shall state the specification requirements not complied with on the 
manufacturer's Certificate of Compliance. When the cargo tank is 
brought into full compliance with the applicable specification, the 
Registered Inspector shall stamp the date of compliance on the 
specification plate. The Registered Inspector shall issue a Certificate 
of Compliance stating details of the particular operations performed on 
the cargo tank, and the date and person (manufacturer, carrier, or 
repair organization) accomplishing the compliance.
    25. In Sec. 178.346-1, new paragraphs (d)(9) and (10) are added to 
read as follows:


Sec. 178.346-1  General requirements.

* * * * *
    (d) * * *
    (9) Single full fillet lap joints without plug welds may be used 
for arc or gas welded longitudinal seams without radiographic 
examination under the following conditions:
    (i) For a truck-mounted cargo tank, no more than two such joints 
may be used on the top half of the tank and no more than two joints may 
be used on the bottom half. They may not be located farther from the 
top and bottom centerline than 16 percent of the shell's circumference.
    (ii) For a self-supporting cargo tank, no more than two such joints 
may be used on the top of the tank. They may not be located farther 
from the top centerline than 12.5 percent of the shell's circumference.
    (iii) Compliance test. Two test specimens of the material to be 
used in the manufacture of a cargo tank must be tested to failure in 
tension. The test specimens must be of the same thicknesses and joint 
configuration as the cargo tank, and joined by the same welding 
procedures. The test specimens may represent all the tanks that are 
made of the same materials and welding procedures, have the same joint 
configuration, and are made in the same facility within 6 months after 
the tests are completed. Before welding, the fit-up of the joints on 
the test specimens must represent production conditions that would 
result in the least joint strength. Evidence of joint fit-up and test 
results must be retained at the manufacturers' facility.
    (iv) Weld joint efficiency. The lower value of stress at failure 
attained in the two tensile test specimens shall be used to compute the 
efficiency of the joint as follows: Determine the failure ratio by 
dividing the stress at failure by the mechanical properties of the 
adjacent metal; this value, when multiplied by 0.75, is the design weld 
joint efficiency.
    (10) The requirements of paragraph UW-9(d), of Section VIII, 
Division 1, ASME Code do not apply.


Sec. 178.346-2  [Amended]

    26. In Sec. 178.346-2, the paragraph (a) designation is removed; 
the phrase ``DOT 406 cargo tanks'' is revised to read ``DOT 406 cargo 
tank motor vehicles''; and in Table II, the heading ``Rated capacity 
(gallons)'' in the first column is revised to read ``Cargo tank motor 
vehicle rated capacity (gallons)''.
    27. In Sec. 178.346-10, the word ``and'' at the end of paragraph 
(b)(1) is removed, the period at the end of paragraph (b)(2) is removed 
and ``; and'' is added in its place, a new paragraph (b)(3) is added 
and paragraphs (c)( 1) and (d)(1) are revised to read as follows:


Sec. 178.346-10  Pressure relief.

* * * * *
    (b) * * *
    (3) Notwithstanding the requirements in Sec. 178.345-10(b), after 
August 31, 1996, each pressure relief valve must be able to withstand a 
dynamic pressure surge reaching 30 psig above the design set pressure 
and sustained above the set pressure for at least 60 milliseconds with 
a total volume of liquid released not exceeding one liter before the 
relief valve recloses to a leak-tight condition. This requirement must 
be met regardless of vehicle orientation. This capability must be 
demonstrated by testing. TTMA RP No. 81, cited at Sec. 178.345-
10(b)(3)(i), is an acceptable test procedure.
    (c) * * *
    (1) Notwithstanding the requirements in Sec. 178.345-10(d), the set 
pressure of each primary relief valve must be not less than 110 percent 
of the MAWP or 3.3 psig, whichever is greater, and not more than 138 
percent of the MAWP. The valve must close at not less than the MAWP and 
remain closed at lower pressures.
* * * * *
    (d) * * *
    (1) Notwithstanding the requirements in Sec. 178.345-10 (e) and 
(g), the primary pressure relief valve must have a venting capacity of 
at least 6,000 SCFH, rated at not greater than 125 percent of the tank 
test pressure and not greater than 3 psig above the MAWP. The venting 
capacity required in Sec. 178.345-10(e) may be rated at these same 
pressures.
* * * * *
    28. In Sec. 178.346-13, paragraph (c) is revised to read as 
follows:


Sec. 178.346-13  Pressure and leakage tests.

* * * * *
    (c) Leakage test. Cargo tanks equipped with vapor collection 
equipment may be leakage tested in accordance with the Environmental 
Protection Agency's ``Method 27--Determination of Vapor Tightness of 
Gasoline Delivery Tank Using Pressure-Vacuum Test,'' as set forth in 40 
CFR Part 60, Appendix A. Acceptance criteria are found at 40 CFR 60.501 
and 60.601.

PART 180--CONTINUING QUALIFICATION AND MAINTENANCE OF PACKAGINGS

    29. The authority citation for part 180 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    30. In Sec. 180.403, a new definition ``Replacement of a barrel'' 
is added, in the appropriate alphabetical order, to read as follows:


Sec. 180.403  Definitions.

* * * * *
    Replacement of a barrel means to replace the existing tank on a 
motor vehicle chassis with an unused (new) tank. For the definition of 
tank, see Sec. 178.345-1(c), Sec. 178.337-1, or Sec. 178.338-1 of this 
subchapter, as applicable.
* * * * *
    31. In Sec. 180.405, paragraph (h) is revised to read as follows:


Sec. 180.405  Qualification of cargo tanks.

* * * * *
    (h) Pressure relief system. Properly functioning reclosing pressure 
relief valves and frangible or fusible vents need not be replaced. 
However, replacement of reclosing pressure relief valves on MC-
specification cargo tanks is authorized subject to the following 
requirements:
    (1) Until August 31, 1998, the owner of a cargo tank may replace a 
reclosing pressure relief device with a device which is in compliance 
with the requirements for pressure relief devices in effect at the time 
the cargo tank specification became superseded. If the pressure relief 
device is installed as an integral part of a manhole cover assembly, 
the manhole cover must comply with the requirements of paragraph (g) of 
this section.
    (2) After August 31, 1998, replacement for any reclosing pressure 
relief valve must be capable of reseating to a leak-tight condition 
after a pressure surge, and the volume of lading released may not 
exceed one liter. Specific performance requirements for these pressure 
relief valves are set forth in Sec. 178.345-10(b)(3) of this 
subchapter.
    (3) As provided in paragraph (c)(2) of this section, the owner of a 
cargo tank may elect to modify reclosing pressure relief devices to 
more recent cargo tank specifications. However, replacement devices 
constructed to the requirements of Sec. 178.345-10 of this subchapter 
must provide the minimum venting capacity required by the original 
specification to which the cargo tank was designed and constructed.
* * * * *


Sec. 180.405  [Amended]

    32. In addition, in Sec. 180.405 the following changes are made:
    a. In paragraph (f)(1)(iii), the phrase ``prescribed in 
Sec. 178.345-3 of the specification'' is revised to read ``prescribed 
in Sec. 178.345-3 of this subchapter or the specification'' .
    b. In paragraph (f)(4) introductory text, the phrase ``and an 
outlet is equipped'' is revised to read ``and except that an outlet is 
equipped''.
    33. In Sec. 180.407, in the table in paragraph (c), immediately 
under the subheading ``Leakage Test'' in the first column, the 
following entry is added and the wording ``All cargo tanks except MC 
338'' is revised to read ``All other cargo tanks except MC 338''; 
paragraph (e)(1) is revised; paragraph (h)(2) is revised; paragraphs 
(i)(5) through (i)(7) are redesignated as paragraphs (i)(6) through 
(i)(8), respectively; the word ``and'' is removed at the end of 
paragraph (i)(4)(viii); the period at the end of paragraph (i)(4)(ix) 
is removed and ``; and'' is added in its place; and new paragraphs 
(i)(4)(x) and (i)(5) are added, to read as follows:


Sec. 180.407  Requirements for test and inspection of specification 
cargo tanks.

* * * * *
    (c) * * * 

    Compliance Dates--Inspections and Retests Under Sec. 180.407(c)     
------------------------------------------------------------------------
 Test or inspection (cargo tank  Date by which first test     Interval  
 specification, configuration,    must be completed (see    period after
          and service)                    note 1)           first test  
------------------------------------------------------------------------
             [Add]                                                      
                                                                        
                                                                        
                              * * * * * * *                             
Leakage Test:                                                           
    MC 330 and MC 331 cargo      Sept. 1, 1991...........  2 years      
     tanks in chlorine service.                                         
                                                                        
                                                                        
                              * * * * * * *                             
------------------------------------------------------------------------
Note 1: If a cargo tank is subject to an applicable inspection or test  
  requirement under the regulations in effect on December 30, 1990, and 
  the due date (as specified by a requirement in effect on December 30, 
  1990) for completing the required inspection or test occurs before the
  compliance date listed in Table I, the earlier date applies.          

* * * * *
    (e) * * * (1) When the cargo tank is not equipped with a manhole or 
inspection opening, or the cargo tank design precludes an internal 
inspection, the tank shall be hydrostatically or pneumatically tested 
in accordance with 180.407(c) and (g).
* * * * *
    (h) * * *
    (2) Cargo tanks equipped with vapor collection equipment may be 
leakage tested in accordance with the Environmental Protection Agency's 
``Method 27--Determination of Vapor Tightness of Gasoline Delivery Tank 
Using Pressure-Vacuum Test,'' as set forth in 40 CFR Part 60, Appendix 
A. Acceptance criteria are found at 40 CFR 60.501 and 60.601.
* * * * *
    (i) * * *
    (4) * * *
    (x) Connecting structures joining multiple cargo tanks of carbon 
steel in a self-supporting cargo tank motor vehicle.
    (5) Minimum thicknesses for MC 300, MC 301, MC 302, MC 303, MC 304, 
MC 305, MC 306, MC 307, MC 310, MC 311, and MC 312 cargo tanks are 
shown in the tables below. The columns headed ``Specified Manufactured 
Thickness'' tabulate the minimum values required for new construction, 
generally found in Tables I and II of each specification. ``In-Service 
Minimum Thicknesses'' are based on 90 percent of the manufactured 
thickness as specified in the DOT specification, rounded to three 
places. 

 Table I.--Minimum Thickness for MC 300, MC 303, MC 304, MC 306, MC 307,
MC 310, MC 311 and MC 312 Specification Cargo Tanks Constructed of Steel
                            and Steel Alloys                            
------------------------------------------------------------------------
                                                     Nominal            
                                                     decimal      In-   
  Specified manufactured thickness (US gauge or    equivalent   service 
                     inches)                           for      minimum 
                                                    reference  thickness
                                                    (inches)    (inches)
------------------------------------------------------------------------
19...............................................      0.0418      0.038
18...............................................      0.0478      0.043
17...............................................      0.0538      0.048
16...............................................      0.0598      0.054
15...............................................      0.0673      0.061
14...............................................      0.0747      0.067
13...............................................      0.0897      0.081
12...............................................      0.1046      0.094
11...............................................      0.1196      0.108
10...............................................      0.1345      0.121
9................................................      0.1495      0.135
8................................................      0.1644      0.148
7................................................      0.1793      0.161
3/16.............................................      0.1875      0.169
1/4..............................................      0.2500      0.225
5/16.............................................      0.3125      0.281
3/8..............................................      0.3750     0.338 
------------------------------------------------------------------------


Table II.--Minimum Thickness for MC 301, MC 302, MC 304, MC 305, MC 306,
   MC 307, MC 311 and MC 312 Specification Cargo Tanks Constructed of   
                      Aluminum and Aluminum Alloys                      
------------------------------------------------------------------------
                                                                  In-   
                                                                service 
          Specified manufactured thickness (inches)             minimum 
                                                               thickness
                                                                (inches)
------------------------------------------------------------------------
0.078........................................................      0.070
0.087........................................................      0.078
0.096........................................................      0.086
0.109........................................................      0.098
0.130........................................................      0.117
0.141........................................................      0.127
0.151........................................................      0.136
0.172........................................................      0.155
0.173........................................................      0.156
0.194........................................................      0.175
0.216........................................................      0.194
0.237........................................................      0.213
0.270........................................................      0.243
0.360........................................................      0.324
0.450........................................................      0.405
0.540........................................................      0.486
------------------------------------------------------------------------

* * * * *


Sec. 180.407  [Amended]

    34. In addition, in Sec. 180.407, the following changes are made:
    a. In paragraph (d)(1)(ii), the wording ``and the cargo tank is not 
equipped'' is revised to read ``or the cargo tank is not equipped''.
    b. In paragraph (e)(2)(ii), the wording ``as specified 
Sec. 180.407(f).'' is revised to read ``as specified in 
Sec. 180.407(f).''.
    c. Paragraph (e)(4) is removed, and paragraph (e)(5) is 
redesignated as paragraph (e)(4).
    d. In paragraph (g)(1)(iv), the word ``minimum'' is removed.
    35. Section 180.413 is revised to read as follows:


Sec. 180.413  Repair, modification, stretching, or rebarrelling of 
cargo tanks.

    (a) General. For purposes of this section, ``stretching'' is not 
considered a ``modification'' and ``rebarrelling'' is not considered a 
``repair.'' Any repair, modification, stretching, or rebarrelling of a 
cargo tank must be performed in conformance with the requirements of 
this section.
    (b) Repair--(1) Non-ASME Code stamped cargo tanks. Any work 
involving repair on an MC 300, MC 301, MC 302, MC 303, MC 304, MC 305, 
MC 306, MC 307, MC 310, MC 311, or MC 312 cargo tank that is not ASME 
Code stamped must be performed by:
    (i) A cargo tank manufacturer holding a valid ASME Certificate of 
Authorization for the use of the ASME ``U'' stamp and registered with 
DOT; or
    (ii) A repair facility holding a valid National Board Certificate 
of Authorization for the use of the National Board ``R'' stamp and 
registered with DOT.
    (2) ASME Code stamped cargo tanks. Any work involving repair on any 
ASME Code stamped cargo tank must be performed by a repair facility 
holding a valid National Board Certificate of Authorization for the use 
of the National Board ``R'' stamp and registered in accordance with 
subpart F of part 107 of subchapter B of this chapter.
    (3) The following provisions apply to cargo tank repairs:
    (i) DOT 406, DOT 407, and DOT 412 cargo tanks must be repaired in 
accordance with the specification requirements in effect either at the 
time of manufacture or at the time of repair;
    (ii) MC 300, MC 301, MC 302, MC 303, MC 305, and MC 306 cargo tanks 
must be repaired in accordance with either the original specification 
or with the DOT 406 specification in effect at the time of repair;
    (iii) MC 304 and MC 307 cargo tanks must be repaired in accordance 
with either the original specification or with the DOT 407 
specification in effect at the time of repair;
    (iv) MC 310, MC 311, and MC 312 cargo tanks must be repaired in 
accordance with either the original specification or with the DOT 412 
specification in effect at the time of the repair;
    (v) MC 338 cargo tanks must be repaired in accordance with the 
specification requirements in effect either at the time of manufacture 
or at the time of repair; and
    (vi) MC 330 and MC 331 cargo tanks must be repaired in accordance 
with the repair procedures described in CGA Technical Bulletin TB-2 and 
the National Board Inspection Code--Provisions for Repair of Pressure 
Vessels. Each cargo tank having cracks or other defects requiring 
welded repairs must meet all of the requirements of Sec. 178.337-16 of 
this subchapter (in effect at the time of the repair), except that 
postweld heat treatment after minor weld repairs is not required. When 
any repair is made of defects revealed by the wet fluorescent magnetic 
particle inspection, including those by grinding, the affected area of 
the cargo tank must again be examined by the wet fluorescent magnetic 
particle method after hydrostatic testing to assure that all defects 
have been removed.
    (4) Prior to any repair work, the cargo tank must be emptied of any 
hazardous material lading. Cargo tanks containing flammable or toxic 
lading must be purged.
    (5) Any repair of a cargo tank involving welding on the shell or 
head must be certified by a Registered Inspector. Any repair of an ASME 
Code ``U'' stamped cargo tank must be in accordance with the National 
Board Inspection Code.
    (6) The suitability of any repair affecting the structural 
integrity of the cargo tank must be determined by testing as prescribed 
in Sec. 180.407.
    (c) Maintenance or replacement of piping, valves, hoses or 
fittings. In the event of repair, maintenance or replacement, any 
piping, valve, or fitting must be properly installed in accordance with 
the provisions of the applicable specification before the cargo tank is 
returned to hazardous materials service. After maintenance or 
replacement which does not involve welding on the cargo tank wall, the 
repaired piping, valves or fittings, the replaced segment of the piping 
must be leak tested. After repair or replacement of piping, valves or 
fittings which involves welding on the cargo tank wall, the entire 
cargo tank, including the repaired or replaced piping, valve or 
fitting, must be pressure tested in accordance with the applicable 
specification. Hoses permanently attached to the cargo tank must be 
tested either before or after installation.
    (d) Modification, stretching, or rebarrelling. Modification, 
stretching or rebarrelling of a cargo tank must conform to the 
following provisions:
    (1) Non-ASME Code stamped cargo tanks. If the modification, 
stretching, or rebarrelling will result in a design type change, then 
it must be approved by a Design Certifying Engineer. Any work involving 
modification, stretching, or rebarrelling on an MC 300, MC 301, MC 302, 
MC 303, MC 304, MC 305, MC 306, MC 307, MC 310, MC 311, or MC 312 cargo 
tank that is not ASME stamped must be performed by:
    (i) A cargo tank manufacturer holding a valid ASME Certificate of 
Authorization for the use of the ASME ``U'' stamp and registered with 
DOT; or
    (ii) A repair facility holding a valid National Board Certificate 
of Authorization for the use of the National Board ``R'' stamp and 
registered with DOT.
    (2) ASME Code stamped cargo tanks. The modification, stretching, or 
rebarrelling on any ASME Code stamped cargo tank must be performed by a 
repair facility holding a valid National Board Certificate of 
Authorization for the use of the National Board ``R'' stamp and 
registered in accordance with subpart F of part 107 of subchapter B of 
this chapter. If the modification, stretching, or rebarrelling will 
result in a design type change, then it must be approved by a Design 
Certifying Engineer.
    (3) All new material and equipment, and equipment affected by the 
modification, stretching or rebarrelling must conform with requirements 
of the specification in effect at the time of such work. In addition, 
the modification, stretching or rebarrelling must be performed such 
that the cargo tank, as modified, stretched or rebarrelled, meets the 
applicable structural integrity requirements (Sec. 178.337-3, 
Sec. 178.338-3, or Sec. 178.345-3 of this subchapter) of the 
specification in effect at the time of such work. The work must conform 
to the requirements of the applicable specification as follows:
    (i) For specification MC 300, MC 301, MC 302, MC 303, MC 305 and MC 
306 cargo tanks, the provisions of either specification MC 306 or DOT 
406 until August 31, 1995 and, thereafter to specification DOT 406 
only;
    (ii) For specification MC 304 and MC 307 cargo tanks, the 
provisions of either specification MC 307 or DOT 407 until August 31, 
1995 and, thereafter to specification DOT 407 only;
    (iii) For specification MC 310, MC 311, and MC 312 cargo tanks, the 
provisions of either specification MC 312 or DOT 412 until August 31, 
1995 and, thereafter to specification DOT 412 only; and
    (iv) For specification MC 330 cargo tanks, the provisions of 
specification MC 331.
    (4) The person performing the modification, stretching, or 
rebarrelling must:
    (i) Have knowledge of the original design concept, particularly 
with respect to structural design analysis, material and welding 
procedures;
    (ii) Assure compliance with the rebuilt cargo tank's structural 
integrity, venting, and accident damage protection requirements;
    (iii) Assure compliance with all applicable Federal Motor Carrier 
Safety Regulations for any newly installed safety equipment;
    (iv) Perform all retest procedures on each cargo tank in accordance 
with the applicable specification and Sec. 180.407;
    (v) Change the existing specification plate to reflect the cargo 
tank as modified, stretched or rebarrelled. This must include the name 
of the person doing the work, his DOT registration number, date, retest 
information, etc. A supplemental specification plate may be installed 
immediately adjacent to the existing plate(s), or the existing 
specification plate may be removed and replaced with a new plate; and
    (vi) On a variable specification cargo tank, install a supplemental 
or new variable specification plate, and replace the specification 
listed on the original specification plate with the words ``see 
variable specification plate''.
    (5) The design of the modified, stretched, or rebarrelled cargo 
tank must be approved by a Design Certifying Engineer registered in 
accordance with subpart F of part 107 of subchapter B of this chapter. 
The Design Certifying Engineer must certify that the modified, 
stretched, or rebarrelled cargo tank meets the structural integrity 
requirements of the applicable specification. The person performing the 
modifying, stretching or rebarrelling and a Registered Inspector must 
certify that the cargo tank is in compliance with this section and the 
applicable specification by issuing a supplemental manufacturer's 
certificate. The registration number of the Registered Inspector and 
the person performing the modification, stretching, or rebarrelling 
must be entered on the certificate. When a cargo tank is rebarrelled, 
it must be designed, constructed and certified in accordance with a 
cargo tank specification currently authorized for construction in Part 
178 of this subchapter.
    (6) If the mounting of the cargo tank on the cargo tank motor 
vehicle involves welding on the cargo tank head or shell, then the 
mounting must be performed as follows:
    (i) Non-ASME Code stamped cargo tanks. For a non-ASME Code stamped 
cargo tank--
    (A) By a cargo tank manufacturer holding an ASME ``U'' stamp, 
registered with DOT, and under the direction of a Design Certifying 
Engineer; or
    (B) By a repair facility holding an ASME ``U'' stamp or a National 
Board ``R'' stamp, registered with DOT, and under the direction of a 
Design Certifying Engineer.
    (ii) ASME Code stamped cargo tank. For an ASME Code stamped cargo 
tank, by a repair facility holding a National Board ``R'' stamp, 
registered in accordance with subpart F of part 107 of subchapter B of 
this chapter, and approved by a Design Certifying Engineer.
    (7) If the mounting of a cargo tank on a cargo tank motor vehicle 
does not involve welding on the cargo tank head or shell, or a change 
or modification of the methods of attachment, then the mounting shall 
be in accordance with the original specification or with the 
specification in effect at the time of the mounting. If the mounting 
involves any change or modification of the methods of attachment, then 
the mounting must be approved by a Design Certifying Engineer.
    (8) Prior to any modification, stretching, or rebarrelling a cargo 
tank must be emptied of any hazardous material lading. Cargo tanks 
containing flammable or toxic lading must be purged.
    (9) Any modification, stretching, or rebarrelling on the cargo tank 
involving welding on the shell or head must be certified by a 
Registered Inspector. Any repair of an ASME Code ``U'' stamped cargo 
tank must be in accordance with the National Board Inspection Code.
    (10) The suitability of modification, stretching, or rebarrelling 
affecting the structural integrity of the cargo tank must be determined 
by testing as prescribed for new manufacture in the applicable 
specification.
    (e) Records. Each owner of a cargo tank must retain at its 
principal place of business all records of repair, modification, 
stretching, or rebarrelling made to each tank during the time the tank 
is in service and for one year thereafter. Copies of these records must 
be retained by a motor carrier, who is not the owner of the cargo tank, 
at its principal place of business during the period the tank is in the 
carrier's service. The seller of a cargo tank shall provide the 
purchaser a copy of the cargo tank Certificate of Compliance, and all 
repair, inspection and test reports upon sale as an MC or DOT cargo 
tank.

    Issued in Washington, DC on October 21, 1994, under authority 
delegated in 49 CFR Part 1.
D.K. Sharma,
Administrator, Research and Special Programs Administration.
[FR Doc. 94-26625 Filed 10-28-94; 1:21 pm]
BILLING CODE 4910-60-P