[Federal Register Volume 72, Number 172 (Thursday, September 6, 2007)]
[Notices]
[Pages 51301-51303]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 07-4309]


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DEPARTMENT OF TRANSPORTATION

Pipeline and Hazardous Materials Safety Administration

[Docket No. PHMSA-2004-19856]


Pipeline Safety: Updated Notification of the Susceptibility to 
Premature Brittle-Like Cracking of Older Plastic Pipe

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

ACTION:  Notice; Issuance of Advisory Bulletin.

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SUMMARY: PHMSA is issuing this updated advisory bulletin to owners and 
operators of natural gas pipeline distribution systems concerning the 
susceptibility of older plastic pipe to premature brittle-like 
cracking. PHMSA previously issued three advisory bulletins on this 
subject: Two on March 11, 1999 and one on November 26, 2002. This 
advisory bulletin expands on the information provided in the three 
prior bulletins by listing two additional pipe materials with poor 
performance histories relative to brittle-like cracking and by updating 
pipeline owners and operators on the ongoing voluntary efforts to 
collect and analyze data on plastic pipe performance. Owners and 
operators of natural gas pipeline distribution systems are encouraged 
to review the three previous advisory bulletins in their entirety.

FOR FURTHER INFORMATION CONTACT: Richard Sanders at (405) 954-7214, or 
by e-mail at [email protected].

SUPPLEMENTARY INFORMATION:

I. National Transportation Safety Board (NTSB) Investigation

    On April 23, 1998, the National Transportation Safety Board (NTSB) 
issued its Special Investigation Report, Brittle-Like Cracking in 
Plastic Pipe for Gas Service, NTSB/SIR-98/01. The report described the 
results of the NTSB's special investigation of polyethylene gas service 
pipe, which addressed three major safety issues: (1) Vulnerability of 
plastic piping to premature failures due to brittle-like cracking; (2) 
adequacy of available guidance relating to the installation and 
protection of plastic piping connections to steel mains; and, (3) 
effectiveness of performance monitoring of plastic pipeline systems to 
detect unacceptable performance in piping systems.
    (1) Vulnerability of plastic piping to premature failures due to 
brittle-like cracking: The NTSB found that failures in polyethylene 
pipe in actual service are frequently brittle-like, slit failures, not 
ductile failures. It concluded the number and similarity of plastic 
pipe accident and non-accident failures indicate past standards used to 
rate the long-term strength of plastic pipe may have overrated the 
strength and resistance to brittle-like cracking for much of the 
plastic pipe manufactured and used for gas service from the 1960s 
through the early 1980s. The NTSB also concluded any potential public 
safety hazards from these failures are likely to be limited to 
locations where stress intensification exists. The NTSB went on to 
state that more durable modern plastic piping materials and better 
strength testing have made the strength ratings of modern plastic 
piping more reliable.
    (2) Adequacy of available guidance relating to the installation and 
protection of plastic piping connections to steel mains: The NTSB 
concluded that gas pipeline operators had insufficient notification of 
the brittle-like failure potential for plastic pipe manufactured and 
used for gas service from the 1960s to the early 1980s. The NTSB also 
concluded this may not have allowed companies to implement adequate 
surveillance and replacement programs for older plastic piping. The 
NTSB explained the Gas Research Institute (GRI) developed a significant 
amount of data on older plastic pipe but the data was published in 
codified terms making it insufficient for use by pipeline system 
operators. The NTSB recommended that manufacturers of resin and pipe, 
industry trade groups and the Federal government do more to alert 
pipeline operators to the role played by stress intensification from 
external forces in the premature failure of plastic pipe due to 
brittle-like cracking.
    (3) Effectiveness of performance monitoring of plastic pipeline 
systems as a way of detecting unacceptable performance in piping 
systems: The NTSB's analysis noted that Federal regulations require 
pipeline operators to have an ongoing program to monitor the 
performance of their pipeline systems. However, the NTSB investigation 
revealed some gas pipeline operators' performance monitoring programs 
did not effectively collect and analyze data to determine the extent of 
possible hazards associated with plastic pipeline systems. The NTSB 
pointed out, ``such a program must be adequate to detect trends as well 
as to identify localized problem areas, and it must be able to relate 
poor performance to specific factors such as plastic piping brands, 
dates of manufacture (or installation dates), and failure conditions.''

[[Page 51302]]

    Copies of this report may be obtained by searching the NTSB Web 
site at www.ntsb.gov.

II. Advisory Bulletins Previously Issued by PHMSA

    The NTSB made several recommendations to PHMSA and to trade 
organizations in its 1998 special investigation report. In response, 
PHMSA issued three advisory bulletins. The first advisory bulletin, 
ADB-99-01, Potential Failure Due to Brittle-Like Cracking of Certain 
Polyethylene Plastic Pipe Manufactured by Century Utility Products Inc, 
was published in the Federal Register (FR) on March 11, 1999 (64 FR 
12211) to advise natural gas pipeline distribution system operators 
that brittle-like cracking may occur on certain polyethylene pipe 
manufactured by Century Utility Products, Inc.
    The second advisory bulletin, ADB-99-02, Potential Failures Due to 
Brittle-Like Cracking of Older Plastic Pipe in Natural Gas Distribution 
Systems, was also published in the Federal Register on March 11, 1999 
(64 FR 12212) to advise natural gas pipeline distribution system 
operators of the potential for brittle-like cracking of plastic pipes 
installed between the 1960s and early 1980s.
    The third advisory bulletin, ADB-02-07, Notification of the 
Susceptibility To Premature Brittle-Like Cracking of Older Plastic 
Pipe, was published in the Federal Register on November 26, 2002 (67 FR 
70806) to reiterate to natural gas pipeline distribution system 
operators the susceptibility of older plastic pipe to premature 
brittle-like cracking. The older polyethylene pipe materials 
specifically identified in ADB-02-07 included, but were not limited to:
     Century Utility Products, Inc. products;
     Low-ductile inner wall ``Aldyl A'' piping manufactured by 
DuPont Company before 1973; and
     Polyethylene gas pipe designated PE 3306.

This third advisory bulletin also listed several environmental, 
installation and service conditions in which plastic piping is used 
that could lead to premature brittle-like cracking failure. PHMSA also 
described six recommended practices for polyethylene gas pipeline 
system operators to aid them with identifying and managing brittle-like 
cracking problems.

III. Plastic Pipe Studies

    Beginning January 25, 2001, the American Gas Association (AGA) 
began to collect data on in-service plastic piping material failures 
with the objective of identifying trends in the performance of these 
materials. The resulting leak survey data, collected from 2001 to 
present, on the county's natural gas distribution systems includes both 
actual failure information and negative reports (reports of no leads) 
submitted voluntarily by participating pipeline operating companies.
    The AGA, PHMSA, and other industry and state organizations continue 
to collect and analyze the data. Unfortunately, the data cannot be 
correlated with the quantities of each plastic pipe material that may 
be in service across the United States. Therefore, the data does not 
assess the failure rates of individual plastic pipe materials on a 
linear basis (i.e. per foot, per mile, etc.). However, the failure data 
reinforces what is historically known about certain older plastic 
piping and components. The data also indicates the susceptibility of 
additional specific materials to brittle-like cracking.

IV. Advisory Bulletin ADB-07-01

    To: Owners and Operators of Natural Gas Pipeline Distribution 
Systems.
    Subject: Updated Notification of the Susceptibility of Older 
Plastic Pipes to Premature Brittle-Like Cracking.
    Advisory: All owners and operators of natural gas distribution 
systems who have installed and operate plastic piping are reminded of 
the phenomenon of brittle-like cracking. Brittle-like cracking refers 
to crack initiation in the pipe wall not immediately resulting in a 
full break followed by stable crack growth at stress levels much lower 
than the stress required for yielding. This results in very tight, 
slit-like, openings and gas leaks. Although significant cracking may 
occur at points of stress concentration and near improperly designed or 
installed fittings, small brittle-like cracks may be difficult to 
detect until a significant amount of gas leaks out of the pipe, and 
potentially migrates into an enclosed space such as a basement. 
Premature brittle-like cracking requires relatively high localized 
stress intensification that may result from geometrical 
discontinuities, excessive bending, improper installation of fittings, 
dents and/or gouges. Because this failure mode exhibits no evidence of 
gross yielding at the failure location, the term brittle-like cracking 
is used. This phenomenon is different from brittle fracture, in which 
the pipe failure causes fragmentation of the pipe.
    All owners and operators of natural gas distribution systems are 
future advised to review the three earlier advisory bulletins on this 
issue. In addition to being available in the Federal Register, these 
advisory bulletins are available in the docket, and on PHMSA's Web site 
at http://phmsa.dot.gov/ under Pipeline Safety Regulations.
    In the first advisory bulletin, ADB-99-01, published on March 11, 
1999 (64 FR 12211), PHMSA advises natural gas distribution system 
operators of the potential for poor resistance to brittle-like cracking 
of certain polyethylene pipe manufactured by Century Utility Products, 
Inc. In the second advisory bulletin, ADB-99-02, published on March 11, 
1999 (64 FR 12212), PHMSA advises natural gas distribution system 
operators of the potential for brittle-like cracking of plastic pipes 
installed between the 1960s and early 1980s.
    In the third advisory bulletin, ADB-02-07, published on November 
26, 2002 (67 FR 70806), PHMSA reiterates to pipeline operators the 
susceptibility of some older plastic pipe to premature brittle-like 
cracking which could substantially reduce the service life of natural 
gas distribution systems and to explain the mission of the Plastic Pipe 
Database Committee (PPDC) ``to develop and maintain a voluntary data 
collection process that supports the analysis of the frequency and 
causes of in-service plastic piping material failures.'' The advisory 
bulletin also lists several environmental, installation and service 
conditions under which plastic piping is used which is used which could 
lead to premature brittle-like cracking failure. PHMSA also describes 
six recommended practices for polyethylene gas pipeline system 
operators to aid them with identifying and managing brittle-like 
cracking problems.
    Lastly, the susceptibility of some polyethylene pipes to brittle-
like cracking is dependent on the resin, pipe processing, and service 
conditions. As noted in ADB-02-07, these older polyethylene pipe 
materials include, but are not limited to:
     Century Utility Products, Inc. products;
     Low-ductile inner wall ``Aldyl A'' piping manufactured by 
DuPont Company before 1973; and
     Polyethylene gas pipe designated PE 3306.

The data now supports adding the following pipe materials to this list:
     Delrin insert tap tees; and,
     Plexco service tee Celcon (polyacetal) caps.

    Authority: 49 U.S.C. chapter 601 and 49 CFR 1.53.


[[Page 51303]]


    Issued in Washington, DC, on August 28, 2007.
Jeffrey D. Wiese,
Associate Administrator for Pipeline Safety.
[FR Doc. 07-4309 Filed 9-5-07; 8:45 am]
BILLING CODE 4910-60-M