[Federal Register Volume 82, Number 77 (Monday, April 24, 2017)]
[Notices]
[Pages 18967-18968]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-05614]


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

DEPARTMENT OF TRANSPORTATION

Pipeline and Hazardous Materials Safety Administration

[Docket No. PHMSA-2016-0078; Notice No. 2016-14]


Hazardous Materials: Use of DOT Specification 39 Cylinders for 
Liquefied Flammable Compressed Gas

AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), 
DOT.

ACTION: Safety advisory notice, revised.

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

SUMMARY: PHMSA is issuing this revised safety advisory notice to 
address concerns of offerors and users of DOT Specification 39 (DOT-39) 
cylinders that exceed 75 cubic inches (in\3\) (1.23 L) and to provide 
clarification of the initial safety advisory notice we issued on this 
subject on December 13, 2016 (Notice No. 2016-14). DOT-39 cylinders 
exceeding 75 in\3\ (1.23 L) should not contain liquefied flammable 
compressed

[[Page 18968]]

cyclopropane, ethane, or ethylene, or liquefied petroleum gases. PHMSA 
advises against the filling or transporting of these gases in DOT-39 
cylinders when the cylinder's internal volume exceeds 75 in\3\ (1.23 
L).

FOR FURTHER INFORMATION CONTACT: Refaat Shafkey, General Engineer, 
Engineering and Research Division, Office of Hazardous Materials 
Safety, Pipeline and Hazardous Materials Safety Administration, U.S. 
Department of Transportation, 1200 New Jersey Avenue SE., Washington, 
DC 20590. Telephone: (202) 366-4545 or email: [email protected].

SUPPLEMENTARY INFORMATION: 

A. Public Action Requested

    PHMSA advises that DOT-39 cylinders having an internal volume 
exceeding 75 cubic inches (in\3\) (1.23 L) should not contain liquefied 
flammable compressed cyclopropane, ethane, or ethylene, or liquefied 
petroleum gases. These gases were historically restricted to this 
volume for shipment in specification cylinders (currently Sec.  
173.304a). This limitation was based on extensive experience under 
special permits and the consideration that, in transportation and 
without the limitation, non-reusable cylinders of larger sizes (and 
lower integrity) would be used in place of authorized higher-integrity 
reusable cylinders. Use of these DOT-39 non-reusable cylinders in 
larger sizes would lower the level of transportation safety previously 
established through use of higher-integrity reusable cylinders for the 
shipment of flammable gases. See the Background section for additional 
information on this issue.

B. Safety Concern

    The release of a liquefied flammable compressed gas as result of 
the failure of a cylinder having an internal volume exceeding 75 in\3\ 
(1.23 L) is a safety concern with potential to cause property damage, 
serious personal injury, or even death. A DOT-39 cylinder, without 
further size restriction, can have a volume of up to 1,526 in\3\ (25 L) 
at a service pressure of 500 psig or less and, as such, can have up to 
20 times the stored energy of a DOT-39 cylinder limited to 75 in\3\ 
(1.23 L). This increased stored energy presents a greater safety risk 
in the event of a release. Additionally, because of the design 
specifications that allow for thinner walls when used at lower 
pressure, these cylinders may be at greater risk from corrosion or 
puncture. Given the known risks associated with cylinders that are 
filled with liquefied flammable compressed gases, PHMSA is issuing this 
revised safety advisory notice to advise offerors and transporters of 
DOT-39 cylinders that those with an internal volume greater than 75 
in\3\ (1.23 L) should not be filled and/or transported with liquefied 
compressed cyclopropane, ethane, or ethylene, or with liquefied 
petroleum gases.

C. Background

    This revised safety advisory notice is being issued in part because 
of safety concerns stemming from a past rulemaking action impacting 
DOT-39 cylinders used for certain liquefied flammable compressed gases. 
In an October 30, 1998 notice of proposed rulemaking (NPRM),\1\ the 
Research and Special Programs Administration (RSPA)--the predecessor 
administration to PHMSA--proposed to extend the 75 in\3\ (1.23 L) 
volume limitation of DOT-39 cylinders to all liquefied flammable 
compressed gases by revising Sec.  173.304 to delete Note 9 from the 
table at Sec.  173.304(a)(2) and adding new sections 173.304a and 
173.304b.\2\ RSPA received several comments in opposition to this 
proposal. RSPA published a final rule on August 8, 2002 and, based on 
the opposing comments, decided not to extend the 75 in\3\ (1.23 L) 
limitation to all liquefied flammable compressed gases in a DOT-39 
cylinder at that time. However, in the process of publishing the final 
rule, the administration inadvertently omitted the 75 in\3\ (1.23 L) 
limitation from the Hazardous Materials Regulations (HMR; 49 CFR parts 
171-180) for cyclopropane, ethane, ethylene, or liquefied petroleum 
gas.\3\ Thus, historically, the HMR limited the internal volume of a 
DOT-39 cylinder to 75 in\3\ (1.23 L) when used for these gases.
---------------------------------------------------------------------------

    \1\ NPRM--Hazardous Materials: Requirements for DOT 
Specification Cylinders (HM-220D) [63 FR 58460].
    \2\ The respective additional requirements for liquefied 
compressed gases have since been redesignated at Sec.  173.304a).
    \3\ Final Rule--Hazardous Materials: Requirements for 
Maintenance, Requalification, Repair and Use of DOT Specification 
Cylinders (HM-220D) [67 FR 51625].
---------------------------------------------------------------------------

    On November 13, 2014, PHMSA accepted a petition for rulemaking (P-
1622) from Worthington Cylinders to address this error. On July 26, 
2016, PHMSA published in the Federal Register an NPRM titled, 
``Hazardous Materials: Miscellaneous Amendments Pertaining to DOT 
Specification Cylinders (RRR),'' [81 FR 48977; Docket No. PHMSA-2011-
0140 (HM-234)] \4\ that proposed to extend the limit on the internal 
volume of DOT-39 cylinders to use with all liquefied flammable 
compressed gases, thus correcting the inadvertent omission and seeking 
comment regarding the possibility of expanding the applicability to 
capture those liquefied flammable compressed gases (e.g., 
difluoromethane (Refrigerant gas R 32)) either not reflected in the 
Sec.  173.304a(a)(2) table or not considered a liquefied petroleum gas. 
Additionally, the NPRM further sought input on past experience with the 
transport of liquefied flammable compressed gases in DOT-39 cylinders 
larger than 75 in\3\ (1.23 L) since implementation of the 2002 final 
rule.
---------------------------------------------------------------------------

    \4\ Hazardous Materials: Miscellaneous Amendments Pertaining to 
DOT Specification Cylinders (RRR) (HM-234) [81 FR 48977], available 
at https://www.gpo.gov/fdsys/pkg/FR-2016-07-26/pdf/2016-16689.pdf.
---------------------------------------------------------------------------

    Given the known risks associated with cylinders that are filled 
with liquefied flammable compressed gases, PHMSA is issuing this 
revised safety advisory notice to advise offerors and transporters of 
DOT-39 cylinders that those with an internal volume greater than 75 
in\3\ (1.23 L) should not be filled and/or transported with liquefied 
compressed cyclopropane, ethane, or ethylene, or with liquefied 
petroleum gases.

    Issued in Washington, DC, on March 16, 2017.
William S. Schoonover,
Associate Administrator for Hazardous Materials Safety, Pipeline and 
Hazardous Materials Safety Administration.
[FR Doc. 2017-05614 Filed 4-21-17; 8:45 am]
 BILLING CODE 4910-60-P