[Federal Register: May 21, 2009 (Volume 74, Number 97)]
[Notices]
[Page 23930-23931]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr21my09-147]
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DEPARTMENT OF TRANSPORTATION
Pipeline and Hazardous Materials Safety Administration
[Docket No. PHMSA-2009-0148]
Pipeline Safety: Potential Low and Variable Yield and Tensile
Strength and Chemical Composition Properties in High Strength Line Pipe
AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA);
DOT.
ACTION: Notice; Issuance of Advisory Bulletin.
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SUMMARY: PHMSA is issuing an advisory bulletin to owners and operators
of natural gas pipeline and hazardous liquid pipeline systems. This
bulletin advises pipeline system owners and operators of the potential
for high grade line pipe installed on projects to exhibit inconsistent
chemical and mechanical properties. Yield strength and tensile strength
properties that do not meet the line pipe specification minimums have
been reported. This advisory bulletin pertains to microalloyed high
strength line pipe grades, generally Grade X-70 and above. PHMSA
recently reviewed metallurgical testing results from several recent
projects indicating pipe joints produced from plate or coil from the
same heat may exhibit variable chemical and mechanical properties by as
much as 15% lower than the strength values specified by the pipe
manufacturer.
FOR FURTHER INFORMATION CONTACT: Alan Mayberry by phone at (202) 366-
5124 or by e-mail at alan.mayberry@dot.gov.
SUPPLEMENTARY INFORMATION:
I. Background
The Federal pipeline safety regulations in 49 CFR Parts 192 and 195
require operators of natural gas transmission, distribution pipeline
systems, and hazardous liquids pipeline systems to use pipe
manufactured by a listed specification in the design of pipelines in
accordance with Sec. Sec. 192.7, 192.55(a), 192.105, and Sec. Sec.
195.3, 195.106, and 195.112.
During pipeline construction in the late-fall of 2008, several
recently installed natural gas transmission pipeline systems
experienced field hydrostatic test failures or excessively expanded
pipe joints of large diameter, microalloyed high grade line pipe.
Metallurgical, mechanical and chemical composition tests of the line
pipe in these cases have shown pipe to have yield strengths, tensile
strengths and/or chemical compositions that did not meet the
requirements of the American Petroleum Institute, Specification for
Line Pipe--5L, (API 5L), 43rd edition for the specified pipe grade. API
5L, product specification level (PSL 2), specifies material
requirements in Section 6 and inspection and testing standards in
Section 9. Even though the pipe supplier provided the pipeline owner or
operator with documentation that the pipe that was delivered to the
owner met these minimum standards, substandard pipe properties were
found in some pipe joints. Specifically, PHMSA was made aware that some
of the line pipe that was installed in these projects had yield
strengths that were up to 15% below the listed API 5L specification
requirements for the specific pipe grade.
Pipeline owners and operators should closely review the
manufacturing procedure specifications for the production and rolling
of the steel plate or coil that is to be used in the production of new
microalloyed high strength line pipe to ensure that pipe steel was
properly rolled into steel plate or coil prior to the pipe mill rolling
process. Pipeline owners and operators should request detailed
manufacturing procedure specifications (MPS) from the pipe manufacturer
as a basis for ensuring critical steel processing parameters such as
the detailed rolling schedule, including, but not limited to rolling
temperature, heating temperature and temperature uniformity, are
controlled throughout the steel rolling process.
Mechanical property and chemical composition tests should be
conducted throughout the steel making, steel rolling and pipe
manufacturing process to ensure uniformity of chemical and
[[Page 23931]]
mechanical properties of the pipe prior to being shipped from the steel
and pipe rolling mills. Low yield and tensile strength test results are
defined as any test results below the minimum specified yield strength
ordered, and tensile strengths below those specified for the specified
grade. An example of pipe standard and grades includes API 5L, PSL 2,
X70 and X80; where X-70 corresponds to steel achieving a specified
minimum yield strength of 70,000 psi; and so on.
II. Advisory Bulletin ADB-09-01
To: Owners and Operators of Hazardous Liquid and Natural Gas
Pipeline Systems.
Subject: Potential Low and Variable Yield and Tensile Strength and
Chemical Composition Properties in High Strength Line Pipe.
Advisory: The Federal pipeline safety regulations in 49 CFR Parts
192 and 195 require operators of natural gas transmission, gas
distribution, and hazardous liquids pipeline systems to use pipe
manufactured by a listed specification in the design of pipelines in
accordance with Sec. Sec. 192.7, 192.55 (a), 192.105, and Sec. Sec.
195.3, 195.106, and 195.112.
PHMSA has identified an integrity issue with respect to
microalloyed high grade line pipe. Tests that have been conducted on
line pipe that has been installed in pipeline systems have shown that
some of the pipe material has yield strengths, tensile strengths, and/
or chemical compositions that do not meet the requirements of the
American Petroleum Institute, Specification for Line Pipe--5L, (API
5L), for PSL 2 and the specified pipe grade. Pipe joints produced from
plate or coil from the same heat may exhibit variable chemical and
mechanical properties. Yield strengths below the minimum specified
yield strength have been reported and yield strengths up to 15% lower
than the strength values on the pipe manufacturer produced mill test
report have also been reported. In some cases, the affected pipe may
successfully pass strength testing methods contained in current
specifications but may lead to a future pipeline integrity issue. The
presence of low yield strength line pipe installed in a pipeline system
may result in increased susceptibility to excessive pipe expansion or
rupture during the pre in-service field hydrostatic strength test.
PHMSA wants to ensure that owners and operators of recently
constructed pipeline systems are aware of the need to investigate
whether their pipelines contain joints of pipe that do not meet minimum
specification requirements. Pipeline owners and operators should review
all MPS mill test reports and other appropriate documentation with
their pipe suppliers to determine if all specification requirements
have been met. Pipeline owners and operators should be aware that small
deviations in steel rolling schedule parameters can have a pronounced
effect on final mechanical properties. The MPS should provide adequate
information concerning process details and inspection methods to ensure
that the materials are uniform and will meet all specification
requirements.
PHMSA advises pipeline owners and operators of in service pipelines
to review their pipe specifications, pipe steel making and rolling MPS,
pipe mill test reports, deformation tool results and all hydrostatic
test failure results for both mill and in place hydrostatic tests to
ensure that inconsistent mechanical and chemical properties are not
inherent in microalloyed line pipe grades on all API 5L--PSL 2, X70 and
X80 line pipe installed during recent construction projects.
Pipeline owners and operators should conduct technical document
reviews on all high strength microalloyed line pipe installed during
this period, review hydrostatic test failures that occurred on
pipelines installed during this period and consider using methods to
detect pipe expansion such as running deformation tools that detect
expanded pipe in these systems if they have any knowledge, findings or
pipe history that lead them to believe their newly constructed high
grade line pipe systems contain line pipe joints that do not meet
specification requirements. Should a pipeline owner or operator have
knowledge of other high grade pipe vintages supplied at early dates
that are in their operating systems that may have this problem, they
should consider conducting reviews as described above with these
operating pipelines to ensure that operating pressures and anomaly
repair procedures are not being conducted outside of their 49 CFR Parts
192 and 195 Code parameters.
Authority: 49 U.S.C. chapter 601 and 49 CFR 1.53.
Issued in Washington, DC, on May 14, 2009.
Jeffrey D. Wiese,
Associate Administrator for Pipeline Safety.
[FR Doc. E9-11815 Filed 5-20-09; 8:45 am]
BILLING CODE 4910-60-P