
[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
