[Federal Register: September 25, 2008 (Volume 73, Number 187)]
[Notices]
[Page 55593-55594]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25se08-107]
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DEPARTMENT OF TRANSPORTATION
Pipeline and Hazardous Materials Safety Administration
[Docket ID PHMSA-2008-0255]
Pipeline Safety: Workshop on Anomaly Assessment and Repair
AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA),
DOT.
ACTION: Notice of Workshop.
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SUMMARY: Recent observations by PHMSA indicate possible inconsistencies
in how natural gas transmission pipeline operators assess and repair
anomalies, such as corrosion defects, and apply the results of
calculations to their decision making for further action. Special
permits granted by PHMSA over the past two years prescribe specific
assessment and repair procedures for pipelines operating under a class
location change and maximum allowable operating pressure special
permit. Moreover, recent research indicating that existing methods of
predicting the remaining strength of corroded pipe could provide non-
conservative results (i.e., the pipe will fail at a pressure lower than
that predicted) in some circumstances. Non-conservative results could
be obtained even when the dimensions of pipeline anomalies are known
with precision.
PHMSA is sponsoring a Workshop on Assessment and Repair of
Anomalies in Pipelines to allow stakeholders of the pipeline safety
community to learn about and discuss these research results, current
evaluation practices, and methods to assure pipeline safety. The
discussion of current evaluation practices and methods to assure
pipeline safety should include: A review of safety factors used to
evaluate anomalies when assessing in-line tool and excavation results,
review of how outside forces and overpressure may effect anomaly
stresses, how ILI tool accuracy is applied to anomaly evaluation, and
how anomaly growth rates in assessments are considered.
DATES: The workshop will be held on October 22, 2008. Name badge pick-
up and on-site registration will be available starting at 7:30 a.m.
with the agenda taking place from 8 a.m. until approximately 5 p.m.
Refer to the meeting Web site for updated agenda and times: http://
primis.phmsa.dot.gov/meetings/Mtg55.mtg. Please note that the workshop
will not be Webcast. However, presentations will be available on the
meeting Web site within 30 days following the workshop.
ADDRESSES: The workshop will be held at the Gaylord National Resort and
Convention Center, 201 Waterfront Street, National Harbor, MD 20745.
Hotel reservations under the ``United States Department of
Transportation 2'' room block for the night of October 21,
2008, can be made at 1-301-965-2000. A daily rate of $233 is available.
The meeting room will be posted at the hotel on the days of the
workshop.
FOR FURTHER INFORMATION CONTACT: Max Kieba at 202-493-0595, or by e-
mail at max.kieba@dot.gov.
SUPPLEMENTARY INFORMATION:
Registration: Members of the public may attend this free workshop.
To help assure that adequate space is provided, all attendees are
encouraged to register for the workshop at http://primis.phmsa.dot.gov/
meetings/Mtg55.mtg. Hotel reservations must be made by contacting the
hotel directly.
Comments: Members of the public may also submit written comments,
either before or after the workshop. Comments should reference Docket
ID PHMSA-2008-0255. Comments may be submitted in the following ways:
E-Gov Web Site: http://www.regulations.gov. This site
allows the public to enter comments on any Federal Register notice
issued by any agency. Follow the instructions for submitting comments.
Fax: 1-202-493-2251.
Mail: Docket Management System, U.S. Department of
Transportation, 1200 New Jersey Avenue, SE., Room W12-140, Washington,
DC 20590.
Hand Delivery: Dot Docket Management System, Room W12-140,
on the ground floor of the West Building, 1200 New Jersey Avenue, SE.,
Washington, DC between 9 a.m. and 5 p.m., Monday through Friday, except
Federal holidays.
Instructions: Identify the Docket ID at the beginning of your
comments. If you submit your comments by mail, submit two copies. If
you wish to receive confirmation that PHMSA has received your comments,
include a self-addressed stamped postcard. Internet users may submit
comments at http://www.regulations.gov.
Note: Comments will be posted without changes or edits to http:/
/www.regulations.gov including any personal information provided.
Please see the Privacy Act heading in the Regulatory Analyses and
Notices section of the Supplementary Information for additional
information.
Privacy Act Statement: Anyone may search the electronic form of all
comments received for any of our dockets. You may review DOT's complete
Privacy Act Statement in the Federal Register published April 11, 2000
(65 FR 19477).
Information on Services for Individuals with Disabilities: For
information on facilities or services for individuals with
disabilities, or to request special assistance at the meeting, please
contact Max Kieba by October 15, 2008.
Issue Description: The current regulations contained in 49 CFR
192.485 and 192.713, allows latitude in methods used for assessing and
remediating pipe with corrosion anomalies to restore the serviceability
of pipe. PHMSA has found a wide variation in operators' interpretation
of how to meet the requirements of pipeline safety regulations in
assessing, evaluating, and remediating corrosion anomalies. PHMSA
emphasizes that, while the workshop will involve issues related to Part
192, the technical discussions on research and methods are of relevance
to hazardous liquid pipeline operators. For this reason, PHMSA also
encourages hazardous liquid pipeline operators to attend the meeting.
Transmission pipelines often operate at high pressures. Pipeline
design requirements assure that pipe has
[[Page 55594]]
sufficient strength to contain these high pressures and to provide an
additional safety margin. Pipeline in-service can become degraded due
to time independent and time dependent threats. Time dependent threats
include corrosion and other defects which can grow over time and, if
allowed to continue unchecked, may reduce the pipe wall thickness to
the point of failure. Time independent threats include excavation
damage, which are one-time events that may damage the pipeline's
protective coating, or the pipe itself (e.g., dent, gouge, crack, or
puncture). The defects caused by time dependent or independent threats
can reduce the safety margin for retaining the pipeline operating
pressure.
Pipeline operators predominantly use one of three accepted methods
to calculate the remaining strength of pipelines containing metal loss
anomalies: (1) B31G, (2) Modified B31G, and (3) RSTRENG. These methods
consider the length and depth of anomalies (i.e., areas of metal loss)
and produce estimates of the pressure at which the pipe will fail.
Pipeline operators are required to use these estimates to (1) determine
whether pipeline pressure must be reduced to provide an additional
safety margin, and (2) determine the urgency with which anomalies must
be investigated, evaluated, and repaired.
In practice, many anomalies are often identified by inspection of
the pipeline using in-line inspection (ILI) tools. These tools provide
estimates of the length and depth of anomalies that are used in
calculating remaining pipeline strength. The dimensions estimated using
ILI tools are subject to uncertainty because of variables that affect
the accuracy in determining wall thickness and length.
Recent research sponsored by PHMSA and industry, evaluated the
accuracy of the methods currently used to calculate the remaining
strength of corroded pipelines. The evaluation used data from
historical and recent bench tests in which pipe with known defects
(some with real corrosion defects and some with intentionally machined
defects) were pressurized to failure. The defect size and pipe
characteristics were used to calculate a predicted failure pressure
using each of the analytical methods being evaluated. The failure
pressure predicted by each method was compared to the empirical failure
pressure determined during the test to identify if the predicted
failure pressure was conservative or non-conservative. This work
involved using the analytical methods to calculate the remaining
strength of pipe containing defects whose dimensions could be measured
with a high degree of precision. In some cases, the pipe failed at
pressures lower than those predicted (i.e., the predicted failure
pressure was non-conservative). This occurred most often for deep
anomalies (e.g., >60% wall loss) in high-strength pipe (e.g., grade API
5L X-52 and above). All of the accepted methods for calculating
remaining pipe strength were found to produce non-conservative
estimates of failure pressure in some instances.
The workshop will allow the review and discussion of appropriate
repair criteria for evaluating anomalies to meet regulatory code
requirements for the permanent field repair of imperfections and
damages. The workshop is also intended to allow representatives of the
pipeline industry, regulatory agencies, the public, and other
stakeholders to discuss the implications of research results and the
potential need for regulatory changes or modification of industry
standards.
Preliminary Workshop Agenda
The workshop will include:
(1) Overview of recent research results,
(2) Perspective of industry and regulators on the implications of
the research results, and
(3) Discussion of issues related to reliable application of methods
for predicting failure pressure of pipe with metal loss defects,
including:
a. Treatment of ILI tool accuracy,
b. Consideration of anomaly growth rates.
c. Appropriate repair criteria.
Refer to the meeting Web site for a more detailed agenda: http://
primis.phmsa.dot.gov/meetings/Mtg55.mtg.
PHMSA publishes requirements for the assessment and repair of
anomalies discovered by ILI tools or direct measurement in 49 CFR Part
192 for gas pipelines and Part 195 for hazardous liquids pipelines.
PHMSA also publishes other anomaly assessment and repair requirements
for pipelines under special permit for class location and alternative
MAOP which vary from and are more stringent than the requirements
contained in regulations. PHMSA plans to discuss assessment and repair
requirements including the application of factors of safety, ILI tool
tolerance, and corrosion growth rates. PHMSA will consider the
discussion at the workshop and comments submitted to the docket in
determining whether changes to regulatory requirements for anomaly
assessment and repair are needed in light of the new research results
and, if so, what those changes should be.
Issued in Washington, DC on September 19, 2008.
William H. Gute,
Deputy Associate Administrator for Pipeline Safety.
[FR Doc. E8-22602 Filed 9-24-08; 8:45 am]
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