[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]



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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 [email protected].

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

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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