3 December 2002
This shows how the National Transportation Safety Board strenghtened warning language about hazards of plastic pipe used in gas transmission pipelines after an announcement misleadingly watered-down the threat.
[Federal Register: December 3, 2002 (Volume 67, Number 232)]
[Notices]
[Page 72027]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03de02-148]
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DEPARTMENT OF TRANSPORTATION
Research and Special Programs Administration
Notification of the Susceptibility to Premature Brittle-Like
Cracking of Older Plastic Pipe
AGENCY: Research and Special Programs Administration (RSPA), DOT.
ACTION: Notice; correction.
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SUMMARY: In the Federal Register of November 26, 2002, (67 FR 70806)
the Research and Special Programs Administration (RSPA) published a
notice document issuing an advisory bulletin on the susceptibility to
premature brittle-like cracking of older plastic pipe (ADB-02-7). RSPA
is submitting this correction notice to reflect minor wording changes
and include a website address.
EFFECTIVE DATE: This correction takes effect November 26, 2002.
FOR FURTHER INFORMATION CONTACT: Gopala K. Vinjamuri, (202) 366-4503,
or by email at gopala.vinjamuri@rspa.dot.gov.
SUPPLEMENTARY INFORMATION:
Correction
The last sentence in the first paragraph of the Supplementary
Information heading under I. Background, reads:
Copies of this report may be obtained by calling NTSB's Public
Inquiry Office at 202-314-6551.
We are revising this sentence to add NTSB's website address. The
sentence is revised to read as follows:
Copies of this report may be obtained by calling NTSB's Public
Inquiry Office at 202-314-6551, or on the NTSB website at www.ntsb.gov.
In the fourth paragraph under SUPPLEMENTARY INFORMATION, the first
sentence reads:
The NTSB report suggests that ........ . Remove the word
``suggests'' and replace with the word ``states''.
In the fourth paragraph under Supplementary Information, the third
sentence reads:
NTSB alleges that ....... . Remove the word ``alleges'' and replace
with the word ``concluded''.
Under II. Advisory Bulletin (ADB-02-7) of the SUPPLEMENTARY
INFORMATION heading, in the second paragraph under Advisory. The fourth
sentence reads:
These older polyethylene pipe materials include the following:
The sentence is revised to read as follows:
These older polyethylene pipe materials include, but are not
limited to:
Issued in Washington, DC on November 27, 2002.
James K. O'Steen,
Deputy Associate Administrator for Pipeline Safety.
[FR Doc. 02-30615 Filed 12-2-02; 8:45 am]
BILLING CODE 4910-60-P
[Federal Register: November 26, 2002 (Volume 67, Number 228)]
[Notices]
[Page 70806-70808]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26no02-108]
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DEPARTMENT OF TRANSPORTATION
Research and Special Programs Administration
Notification of the Susceptibility To Premature Brittle-Like
Cracking of Older Plastic Pipe
AGENCY: Research and Special Programs Administration (RSPA), DOT.
ACTION: Notice; issuance of advisory bulletin.
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SUMMARY: RSPA is issuing this follow-up advisory bulletin to owners and
operators of natural gas distribution systems to inform them of the
susceptibility to premature brittle-like cracking of older plastic pipe
and the voluntary efforts to collect and analyze data on plastic pipe
performance. A Special Investigation Report issued by the National
Transportation Safety Board (NTSB) described how plastic pipe installed
in natural gas distribution systems from the 1960s through the early
1980s may be vulnerable to brittle-like cracking resulting in gas
leakage and potential hazards to the public and property. On March 11,
1999, RSPA issued two advisory bulletins on this issue. The first
bulletin reminded natural gas distribution system operators of the
potential poor resistance to brittle-like cracking of certain
polyethylene pipe manufactured by Century Utility Products, Inc. The
second bulletin advised natural gas distribution system operators of
the potential vulnerability of older plastic pipe to brittle-like
cracking.
ADDRESSES: This document can be viewed on the Office of Pipeline Safety
(OPS) home page at: http://ops.dot.gov.
FOR FURTHER INFORMATION CONTACT: Gopala K. Vinjamuri, (202) 366-4503,
or by e-mail at gopala.vinjamuri@rspa.dot.gov.
SUPPLEMENTARY INFORMATION:
I. Background
On April 23, 1998, NTSB issued a Special Investigation Report
(NTSB/SIR-98/01), Brittle-like Cracking in Plastic Pipe for Gas
Service, that describes how plastic pipe installed in natural gas
distribution systems from the 1960s through the early 1980s may be
vulnerable to brittle-like cracking resulting in gas leakage and
potential hazards to the public and property. An NTSB survey of the
accident history of plastic pipe suggested that the material may be
susceptible to premature brittle-like cracking under conditions of
local stress intensification because of improper joining or
installation procedures. Hundreds of thousands of miles of plastic pipe
have been installed, with a significant amount installed prior to the
early-1980s. NTSB believes any vulnerability of this material to
premature cracking could represent a potentially serious hazard to
public safety. Copies of this report may be obtained by calling NTSB's
Public Inquiry Office at 202-314-6551.
RSPA has already issued two advisory bulletins on this issue. The
first advisory bulletin, ADB-99-01, which was published in the Federal
Register on March 11, 1999 (47 FR 12211), reminded natural gas
distribution system operators of the potential poor resistance to
brittle-like cracking of certain polyethylene pipe manufactured by
Century Utility Products, Inc. The second advisory bulletin, ADB-99-02,
also published in the Federal Register on March 11, 1999 (47 FR 12212),
advised natural gas distribution system operators of the potential
brittle-like cracking vulnerability of plastic pipe installed between
the 1960s and early 1980s.
The phenomenon of brittle-like cracking in plastic pipe as
described in the NTSB report and generally understood within the
plastic pipeline industry relates to a part-through crack initiation in
the pipe wall followed by stable crack growth at stress levels much
lower than the stress required for yielding, resulting in a 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 be a result from geometrical
discontinuities, excessive bending, improper installation of fittings,
and dents and 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.
The NTSB report suggests that the combination of more durable
plastic pipe materials and more realistic strength testing has improved
the reliability of estimates of the long-term hydrostatic strength of
modern plastic pipe and fittings. The report also documents that older
polyethylene pipe, manufactured from the 1960s through the early 1980s,
may fail at lower stresses and after less time than was originally
projected. NTSB alleges that
[[Page 70807]]
past standards used to rate the long-term strength of plastic pipe may
have overrated the strength and resistance to brittle-like cracking of
much of the plastic pipe manufactured and used for gas service from the
1960s through the early 1980s.
In 1998, NTSB made several recommendations to trade organizations
and to RSPA on the need for a better understanding of the
susceptibility of plastic pipe to brittle-like cracking. This advisory
bulletin responds to one of the NTSB recommendations. It is that RSPA
``[d]etermine the extent of the susceptibility to premature brittle-
like cracking of older plastic piping (beyond that marketed by Century
Utilities Products Inc.) that remains in use for gas service
nationwide. Inform gas system operators of the findings and require
them to closely monitor the performance of the older plastic piping and
to identify and replace, in a timely manner, any of the piping that
indicates poor performance based on such evaluation factors as
installation, operating, and environmental conditions; piping failure
characteristics; and leak history.''
In order to obtain the most complete information on the extent of
the susceptibility to premature brittle-like cracking of older plastic
pipe, a meeting was convened in May 1999 with all the stakeholders to
determine how information on older plastic pipe could be assembled. The
meeting included representatives of the American Gas Association (AGA),
the American Public Gas Association (APGA), the Gas Research Institute
(GRI) (now the Gas Technology Institute), the Midwest Energy
Association (MEA), and the Plastic Pipe Institute (PPI).
As a result of the May 1999 meeting, the Joint Government-Industry
Plastic Pipe Study Committee was formed to address the recommendations
of the NTSB Special Investigation Report. The committee held three
separate meetings to prepare a draft response to the NTSB
recommendations and a draft industry notification of brittle-like
cracking problems, the subject of this advisory bulletin. The committee
membership consisted of a representative from OPS, a gas distribution
operator from AGA, and the Transportation Safety Institute. Meetings
were facilitated by General Physics Corporation, Columbia, MD. One of
the committee findings was that there is a lack of data available from
the industry to completely identify older plastic pipe that is still in
service and may be susceptible to brittle-like cracking.
This finding led to the formation of the Plastic Pipe Database
Committee (PPDC) to develop a process for gathering data on future
plastic pipe failures with involvement from the states, which have
assumed the authority from OPS over gas distribution systems, where
most of the plastic pipe is installed. The PPDC is comprised of
representatives from Federal and State regulatory agencies and from the
natural gas and plastic pipe industries. Members include AGA, APGA,
PPI, the National Association of Regulatory Utility Commissioners
(NARUC), the National Association of Pipeline Safety Representatives
(NAPSR), and OPS.
The PPDC database is expected to improve the knowledge base of gas
utility operators and regulators and is intended to help reveal any
failure trends associated with older plastic piping materials. The
PPDC's mission is ``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.'' It provides an opportunity
for government and industry to work together to evaluate the extent of
plastic pipe performance problems and to mitigate any risks to safety.
The PPDC started gathering data in January 2001 from OPS and State
pipeline safety agencies. For more information on the PPDC, go to the
AGA Web page (http://www.aga.org), and enter ``PPDC'' in the keyword
search.
II. Advisory Bulletin (ADB-02-7)
To: Owners and Operators of Natural Gas Distribution Pipeline
Systems.
Subject: Notification of the Susceptibility to Premature Brittle-
like Cracking of Older Plastic Pipe.
Advisory: In recent years, brittle-like cracking has been observed
in some polyethylene pipes installed in gas service through the early
1980s. This brittle-like cracking (also known as slow crack growth) can
substantially reduce the service life of polyethylene piping systems.
The susceptibility of some polyethylene pipes to brittle-like
cracking is dependent on the resin, pipe processing, and service
conditions. A number of studies have been conducted on older
polyethylene pipe. These studies have shown that some of these older
polyethylene pipes are more susceptible to brittle-like cracking than
current materials. These older polyethylene pipe materials include the
following:
[sbull] Century Utility Products, Inc. products.
[sbull] Low-ductile inner wall ``Aldyl A'' piping manufactured by
Dupont Company before 1973.
[sbull] Polyethylene gas pipe designated PE 3306. (As a result of
poor performance this designation was removed from ASTM D-2513.)
The environmental, installation, and service conditions under which
the piping is used are factors that could lead to premature brittle-
like cracking of these older materials. These conditions include, but
are not limited to:
[sbull] Inadequate support and backfill during installation.
[sbull] Rock impingement.
[sbull] Shear/bending stresses due to differential settlement
resulting from factors such as:
--Excavation in close proximity to polyethylene piping
--Directional drilling in close proximity to polyethylene piping
--Frost heave
[sbull] Bending stresses due to pipe installations with bends
exceeding recommended practices.
[sbull] Damaging squeeze-off practices.
Service temperatures and service pressures also influence the
service life of polyethylene piping. Piping installed in areas with
higher ground temperatures or operated under higher operating pressures
will have a shorter life.
Gas system operators may experience an increase in failure rates
with a susceptible material. A susceptible material may have leak-free
performance for a number of years before brittle-like cracks occur. An
increase in the occurrence of leaks will typically be the first
indication of a brittle-like cracking problem. It is the responsibility
of each pipeline operator to monitor the performance of their gas
system. RSPA issues the following recommendations to aid operators in
identifying and managing brittle-like cracking problems in polyethylene
piping involving taking appropriate action, including replacement, to
mitigate any risks to public safety.
Because systems without known susceptible materials may also
experience brittle-like cracking problems, RSPA recommends that all
operators implement the following practices for all polyethylene piping
systems:
1. Review system records to determine if any known susceptible
materials have been installed in the system. Both engineering and
purchasing records should be reviewed. Based on the available records,
identify the location of the susceptible materials. More frequent
inspection and leak surveys should be performed on systems that have
exhibited brittle-like cracking failures of known susceptible
materials.
[[Page 70808]]
2. Establish a process to identify brittle-like cracking failures.
Identification of failure types and site installation conditions can
yield valuable information that can be used in predicting the
performance of the system.
3. Use a consistent record format to collect data on system
failures. The AGA Plastic Failure Report form (Appendix F of the AGA
Plastic Pipe Manual) provides an example of a report for the collection
of failure data.
4. Collect failure samples of polyethylene piping exhibiting
brittle-like cracking. Evidence of brittle-like cracking may warrant
laboratory testing. Although every failure may not warrant testing,
collecting samples at the time of failure would provide the opportunity
to conduct future testing should it be deemed necessary.
5. Whenever possible record the print line from any piping that has
been involved in a failure. The print line information can be used to
identify the resin, manufacturer and year of manufacture for plastic
piping.
6. For systems where there is no record of the piping material,
consider recording print line data when piping is excavated for other
reasons. Recording the print line data can aid in establishing the type
and extent of polyethylene piping used in the system.
(49 U.S.C. chapter 601; 49 CFR 1.53)
Issued in Washington, DC, on November 21, 2002.
Stacey L. Gerard,
Associate Administrator for Pipeline Safety.
[FR Doc. 02-30055 Filed 11-25-02; 8:45 am]
BILLING CODE 4910-60-P