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Safety Recommendation Details

Safety Recommendation P-04-006
Details
Synopsis: About 2:12 a.m., central daylight time, on July 4, 2002, an Enbridge 34-inch-diameter steel pipeline ruptured in a marsh west of Cohasset, Minnesota. Approximately 6,000 barrels (252,000 gallons) of crude oil were released from the pipeline as a result of the rupture. No deaths or injuries resulted from the release. The cost of the accident was approximately $5.6 million, which includes the cost of cleanup and recovery, value of lost product, and damage to the property of the pipeline operator and others. The National Transportation Safety Board determines that the probable cause of the July 4, 2002, pipeline rupture near Cohasset, Minnesota, was inadequate loading of the pipe for transportation that allowed a fatigue crack to initiate along the seam of the longitudinal weld during transit. After the pipe was installed, the fatigue crack grew with pressure cycle stresses until the crack reached a critical size and the pipe ruptured.
Recommendation: TO THE AMERICAN PETROLEUM INSTITUTE: Review the equations in American Petroleum Institute RP 5L1, Recommended Practice for Railroad Transportation of Line Pipe, and American Petroleum Institute RP 5LW, Recommended Practice for Transportation of Line Pipe on Barges and Marine Vessels, for calculating the static load stresses at the bearing or separator strips and revise the recommended practices based on that review.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Pipeline
Location: Cohasset, MN, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA02MP002
Accident Reports: Rupture of Enbridge Pipeline and Release of Crude Oil
Report #: PAR-04-01
Accident Date: 7/4/2002
Issue Date: 7/1/2004
Date Closed: 4/16/2010
Addressee(s) and Addressee Status: American Petroleum Institute (Closed - Acceptable Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: American Petroleum Institute
Date: 4/16/2010
Response: NMC# 103381: The NTSB is pleased that in September 2009, the API issued the seventh edition of API RP 5L1, Recommended Practice for Railroad Transportation of Line Pipe (September 2009) and the third edition of API RP 5LW, Recommended Practice for Transportation of Line Pipe on Barges and Marine Vessels (September 2009). Because these new editions satisfy Safety Recommendation P-04-6, the recommendation is classified CLOSED -- ACCEPTABLE ACTION.

From: American Petroleum Institute
To: NTSB
Date: 11/18/2009
Response: NMC# 103381: 11-18-09: - From Jack Gerard, President and Chief Executive Officer: API’s Committee on the Standardization of Tubular Goods undertook a complete review of the two standards based on the above recommendation and kept the NTSB informed of its progress, including inviting NTSB staff to attend meetings and discuss the recommendation. After research and analysis, the revisions to API Recommended Practices 5L1 and 5LW were balloted and approved in accordance with API’s Procedures for Standards Development. We believe the changes to these documents are fully responsive to the NTSB recommendation. In order to facilitate your review of the changes that have been incorporated into the revised documents, we have enclosed a detailed synopsis of the revisions made to each document in response to the recommendation as along with a copy of each publication. Should you need additional copies or if you have further questions, please contact David Miller, API Standards Director at 202-682-8159. Sincerely, Jack Gerard. Summary of Changes to API RP 5L1, Recommended Practice for Railroad Transportation of Line Pipe and API RP SLW, Recommended Practice for Transportation of Line Pipe on Barges and Marine Vessels In Response to NTSB Recommendation P-04-06 The seventh edition of API RP 5L1, Recommended Practice for Railroad Transportation of Line Pipe (September 2009) and the third edition of API RP 5LW, Recommended Practice for Transportation of Line Pipe on Barges and Marine Vessels (September 2009) are updates to the sixth and second editions published in June 2002 and December 1996/Reaffirmation date September 2003, respectively. These new editions respond to National Transportation Safety Board recommendation P-04-06 and include other updates and revisions as determined by the API 5L1/5LW work group. NTSB RECOMMENDATION TO API Review the equations in American Petroleum Institute RP 5L1, Recommended Practice for Railroad Transportation of Line Pipe and API RP 5LW, Recommended Practice for Transportation by Line Pipe on barges and Marine Vessels, for calculating the static load stresses at the bearing or separator strips and revise the recommended practices based on that review. MAJOR CHANGES IN API RPs 5L1. SEVENTH EDITION Included in the Introduction of the seventh edition: “The seventh edition of this RP incorporates revisions in light of an identification of inaccuracies in the equations for static load stress, which were derived by numerical methods decades ago. These inaccuracies were discovered when finite element analysis methods were used to check the equations. API is working to update and revise these equations for a future edition. Notwithstanding these inaccuracies, there have been no confirmed transit fatigue failures reported in pipe loaded in accordance with previous editions of this document. The stress equations and associated charts were removed (Load stresses for Pipe with D/t >50). Recommended provisions for loading procedures were included (see section 5.2) MAJOR CHANGES IN API RP 5LW. THIRD EDITION Included in the Introduction of the third edition: The third edition of this RP incorporates revisions in light of an identification of inaccuracies in the equations for static load stress, which were derived by numerical methods decades ago. These inaccuracies were discovered when finite element analysis methods were used to check the equations. API is working to update and revise these equations for a future edition. Notwithstanding these inaccuracies, there have been no confirmed transit fatigue failures reported in pipe loaded in accordance with previous editions of this document. The stress equations and associated charts were removed (Load stresses for Pipe with D/t >50).

From: NTSB
To: American Petroleum Institute
Date: 6/19/2008
Response: The Safety Board notes that the API combined resources with Pipeline Research Council International last year to address this issue. According to Mr. Bellinger’s e-mail, additional finite element analysis was also completed last year, and proposed refinements to the stress equations in RP 5L1 and RP 5LW were made in January 2008. Further, the committee is now looking at the practical implication of the new equations with regard to loading pipe, and the API plans to propose final text for approval at its June 2008 standards conference. Mr. Bellinger also advised that the API expects to publish the recommended changes to RP 5L1 and RP 5LW by fall 2008. Pending completion of the recommended action, Safety Recommendation P-04-6 is classified OPEN -- ACCEPTABLE RESPONSE. We would appreciate receiving periodic updates on the API’s progress on this issue. Please send a copy of the proposed changes to RP 5L1 and RP 5LW when they become available.

From: American Petroleum Institute
To: NTSB
Date: 3/25/2008
Response: Letter Mail Controlled 3/26/2008 11:47:32 AM MC# 2080150: 3-25-08 e-mail: - From Brad Bellinger, American Petroleum Institute: API combined resources with PRCI last year to leverage a parallel effort. Additional FEA analysis [FEA is an acronym meaning finite element analysis was also completed last year and proposed refinements to the stress equations in RP 5L1 and RP 5LW were made at the January 2008 meeting. The committee is now looking at the practical implication of the new equations with regard to loading pipe. We plan to propose final text for letter ballot at the June API standards conference. Assuming all goes well, API will publish changes to 5L1 and 5LW by the fall of this year.

From: NTSB
To: American Petroleum Institute
Date: 12/17/2004
Response: The Safety Board notes that the API forwarded the recommendation for consideration and action to the API Task Force on Line Pipe, which is responsible for the maintenance and revision of API RP 5L1 and RP 5LW. According to Mr. Matheson's letter, this task force, which reports to the API Subcommittee on Tubular Goods, has agreed to review the two API standards and is currently soliciting information from the industry regarding company practices for the transportation of line pipe. Pending completion of the recommended action, Safety Recommendation P-04-6 is classified OPEN -- ACCEPTABLE RESPONSE. We would appreciate receiving periodic updates on the API's progress on this issue.

From: American Petroleum Institute
To: NTSB
Date: 8/10/2004
Response: Letter Mail Controlled 8/17/2004 9:40:15 AM MC# 2040513 - From Marty Matheson, Director, Pipeline: API has taken the following actions: 1. API has forwarded the NTSB report on this accident to the operations managers of the API pipeline member companies. This report provides new information to operators about fatigue cracking related to the transportation of pipe joints and about the capabilities of elastic wave and UltraScan CD in-line inspection tools. Forwarded July 19, 2004. 2. API requested a copy of the Materials Laboratory Study, which includes the comparison of the loading practices used against the API standards, a finite element analysis of the static stress developed in pipe for the two loading practices, and an assessment of the effect of the deflection of the pipe. NTSB provided the study to API on August 5, 2004 (Mr. Rod Dyck). 3. API has forwarded the NTSB safety recommendation letter (Rosenker 7/6/04), the full NTSB accident investigation report (Rupture of Enbridge Pipeline and Release of Crude Oil Near Cohasset, Minnesota), and the Materials Laboratory Study to the chairman and vice-chairman of the API Task Force on Line Pipe, which is the committee responsible for the maintenance and revision of API RP 5L1 and RP 5LW, for consideration and action. This task force reports to the API Subcommittee on Tubular Goods. The task force has agreed to review the two API standards and is currently soliciting information from the industry regarding company practices for the transportation of line pipe.