[Federal Register Volume 64, Number 47 (Thursday, March 11, 1999)]
[Notices]
[Pages 12211-12212]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-6013]
[[Page 12211]]
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DEPARTMENT OF TRANSPORTATION
Research and Special Programs Administration
Potential Failure Due to Brittle-Like Cracking Certain
Polyethylene Plastic Pipe Manufactured by Century Utility Products Inc
AGENCY: Research and Special Programs Administration (RSPA), DOT.
ACTION: Notice; issuance of advisory bulletin on Century polyethylene
gas pipe to owners and operators of natural gas distribution systems.
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SUMMARY: This advisory bulletin is directed at owners and operators of
natural gas distribution systems that have installed plastic pipe
extruded by Century Utility Products Inc. from Union Carbide
Corporation's DHDA 2077 Tan medium density polyethylene resin (Century
pipe). Pipe manufactured between 1970 and 1973 may fail in service due
to its poor resistance to brittle-like cracking. Operators with Century
pipe in their systems should closely monitor this pipe for leaks with
increased leak survey frequency. Century pipe that may be improperly
installed, repaired, or operating in an environment that impairs pipe
strength should be replaced.
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 (Krishna) Vinjamuri at (202)
366-4503, or by E-mail at vinjamuri@rspa.dot.gov.
SUPPLEMENTARY INFORMATION:
I. Background
The National Transportation Safety Board (NTSB) recently published
the results of a special investigation into accidents that involved
plastic pipe currently in use to deliver natural gas to residential and
business use. The report, Brittle-Like Cracking in Plastic Pipe for Gas
Service (NTSB/SIR-98/01; April 23, 1998) suggested that ``[d]espite the
general acceptance of plastic piping as a safe and economical
alternative to piping made of steel and other materials, [a] number of
pipeline accidents investigated have involved plastic piping that
cracked in a brittle-like manner.'' Copies of this report may be
obtained from NTSB Public Inquiry Office by calling 202-314-6551.
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 opening and gas leak. This failure mode is difficult to
detect until significant amount of gas leaks out of the pipe, and
potentially migrates into closed space such as basements of dwellings.
Premature brittle-like cracking requires relatively high localized
stress intensification that may be a result from geometrical
discontinuities, excessive bending, improper fitting assemblies, and/or
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 failure results in fragmentation of the pipe.
NTSB also alleged that the guidance provided by manufacturers and
industry standards for the installation of plastic pipe is inadequate
for limiting stress intensification, particularly at plastic service
connections to steel mains, many of these connections may have been
installed without adequate protection from shear and bending forces
that may result in brittle-like cracking.
Century Pipe
Between 1970 and 1973, Century Utility Products Inc. (a/k/a
AMDEVCO), now defunct, marketed medium density polyethylene plastic
pipe and fittings (Century pipe) in sizes ranging from \1/2\ inch to 4
inches for use in natural gas distribution. These plastic pipes and
fittings were manufactured by extrusion from Union Carbide
Corporation's DHDA 2077 Tan resin, and was marked PE 2306 in accordance
with American Society for Testing and Materials (ASTM) standards.
Following investigation of a series of incidents, including the
December 2, 1979, explosion in a residence in Tuscola, Illinois, and
the October 17, 1994, accident in Waterloo, Iowa, that resulted in
several fatalities, it was established that the Union Carbide's DHDA
2077 Tan resin lacks adequate resistance to brittle-like cracking and
is prone to relatively short life when subjected to high local stress
concentration. The pipe in the Tuscola, Illinois, accident failed in
less than 8 years, and the pipe in the Waterloo, Iowa, accident failed
within 23 years in service. It has been established that Century pipe
exhibited significantly higher leak rate in comparison with other
polyethylene, steel, and cast iron pipe used in natural gas
distribution systems.
Following the Waterloo, Iowa, accident, RSPA has taken number of
actions, including gathering Century pipe installation data. Also,
remedial action has been taken by various operators in mid-western
states where much of the Century pipe produced was known to have been
installed. It is RSPA's understanding that the operators having Century
pipe in their systems have initiated close monitoring and some have
replacement program in progress.
NTSB recommended that RSPA notify owners and operators of natural
gas systems who continue to use Century pipe of the potential for
premature failures by brittle-like cracking and the need to ``[d]evelop
a plan to closely monitor the performance of and to identify and
replace, in a timely manner, any piping that indicates poor performance
based on such evaluation factors as installation, operating and
environmental conditions, piping failure characteristics and leak
history.''
II. Advisory Bulletin (ADB-99-01)
To: Owners and Operators of Natural Gas Distribution Pipeline
Systems.
Subject: Susceptibility of certain polyethylene pipe manufactured
by Century Utility Products Inc. to premature failure due to brittle-
like cracking.
Purpose: To advise natural gas distribution pipeline owners and
operators of the need to closely monitor and replace as necessary
polyethylene natural gas pipe manufactured by Century Utility Products
Inc. between 1970 and 1973 that is susceptible to brittle-like
cracking.
Advisory: All owners and operators of natural gas distribution
systems who have installed and continue to use polyethylene pipe
extruded by Century Utility Products Inc, (now defunct) from the resin
DHDA 2077 Tan resin manufactured by Union Carbide Corporation during
the period 1970 to 1973 (Century pipe) are advised that this pipe may
be susceptible to premature failure due to brittle-like cracking.
Premature failures by brittle-like cracking of Century pipe is known to
occur due to poor resin characteristics, excessive local stress
intensification caused by improper joints, improper installation, and
environments detrimental to pipe long-term strength. All distribution
systems containing Century pipe should be monitored to identify pipe
subject to brittle-like cracking. Remedial action, including
replacement, should be taken to protect system integrity and public
safety.
In addition, in light of the potential susceptibility of Century
pipe to brittle-like cracking, RSPA recommends that
[[Page 12212]]
each natural gas distribution system operator with Century pipe revise
their plastic pipe repair procedure(s) to exclude pipe pinching for
isolating sections of Century pipe. Additionally, RSPA recommends
replacement of any Century pipe segment that has a significant leak
history or which for any reason is of suspect integrity.
Authority: 49 U.S.C. Chapter 601; 49 CFR 1.53.
Issued in Washington, DC on March 5, 1999.
Richard B. Felder,
Associate Administrator for Pipeline Safety.
[FR Doc. 99-6013 Filed 3-10-99; 8:45 am]
BILLING CODE 4910-60-P
