PIPELINE OCCURRENCE REPORT P96H0008 CRUDE OIL PIPELINE RUPTURE INTERPROVINCIAL PIPE LINE INC. LINE 3, MILE POST 506.6830 NEAR GLENAVON, SASKATCHEWAN 27 FEBRUARY 1996 The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety. It is not the function of the Board to assign fault of determine civil or criminal liability. Pipeline Occurrence Report Crude Oil Pipeline Rupture Interprovincial Pipe Line Inc. Line 3, Mile Post 506.6830 Near Glenavon, Saskatchewan 27 February 1996 Report Number P96H0008 Synopsis At 0619 mountain standard time, on 27 February 1996, a rupture occurred on the Interprovincial Pipe Line Inc. 864-millimetre outside diameter pipeline designated as Line 3, at Mile Post 506.6830 near Glenavon, Saskatchewan. Approximately 800 cubic metres (m3) (5,000 barrels) of heavy crude oil was released and collected in a low-lying area near the site. Approximately 600 m3 (3,800 barrels) of heavy crude oil was recovered. The Board determined that the rupture was caused by excessive narrow, axial, external corrosion located adjacent and running parallel to the longitudinal seam weld of the pipe, which was assisted by low-pH stress corrosion cracking and was not identified through the company's ongoing pipeline integrity program called the Susceptibility Investigation Action Plan. Ce rapport est également disponible en français. 1.0 Factual Information ....................................................................................... 1 1.1 The Accident ................................................................................................................................. 1 1.2 Injuries .......................................................................................................................................... 2 1.3 Damage to Equipment - Product Lost .......................................................................................... 2 1.4 Weather ......................................................................................................................................... 3 1.5 Particulars of the Pipeline System ................................................................................................ 3 1.6 Commodity Pipeline Operations ................................................................................................... 4 1.7 Cathodic Protection on Line 3 ...................................................................................................... 5 1.8 Analysis of the Soil and Water at the Occurrence Site ................................................................ 5 1.9 Metallurgical Testing of the Pipeline Steel .................................................................................. 6 1.10 Low-pH Stress Corrosion Cracking .............................................................................................. 7 1.11 Exterior Polyethylene Tape Coating System on Line 3 ............................................................... 9 1.12 Analysis of Pipe Corrosion Products and Polyethylene Tape Residues .................................... 10 1.13 History of Previous Ruptures, Leaks and Pipe Replacements on Line 3 ................................... 10 1.14 Susceptibility Investigation Action Plan for Line 3 ................................................................... 11 1.15 Initiatives Taken after the Occurrence ........................................................................................ 13 2.0 Analysis ....................................................................................................... 15 2.1 Introduction ................................................................................................................................. 15 2.2 Consideration of the Facts .......................................................................................................... 15 2.2.1 Susceptibility Investigation Action Plan for Line 3 ................................................................... 15 2.2.2 Exterior Polyethylene Tape Coating and Environmental Conditions ........................................ 16 2.2.3 Low-pH Stress Corrosion Cracking on Line 3 ........................................................................... 17 2.2.4 Other Environmentally Assisted Cracking Mechanisms on Line 3 ........................................... 18 2.2.5 History of Previous Pipeline Occurrences - Glenavon to Langbank ......................................... 18 2.2.6 Exterior Pipe Cleaning Methods ................................................................................................. 19 2.2.7 Initiatives Taken after the Occurrence ........................................................................................ 20 3.0 Conclusions ................................................................................................. 23 3.1 Findings ....................................................................................................................................... 23 3.2 Cause ........................................................................................................................................... 24 4.0 Safety Action ............................................................................................... 25 4.1 Action Taken ............................................................................................................................... 25 4.1.1 IPL=s Integrity Management Programs ....................................................................................... 25 4.2 Action Required .......................................................................................................................... 25 4.2.1 Narrow, Axial, External Corrosion ............................................................................................. 25 4.3 Safety Concern ............................................................................................................................ 26 4.3.1 Self-Adhesive Coatings .............................................................................................................. 26 TABLE OF CONTENTS 5.0 Appendices Appendix A - History of Present and Previous Ruptures, Leaks and Pipe Replacements on Line 3 ....................................................................................................................... 27 Appendix B - Glossary ......................................................................................................................... 29 TRANSPORTATION SAFETY BOARD v FACTUAL INFORMATION 1.0 Factual Information 1.1 The Accident On 27 February 1996, at 0619, the Interprovincial Pipe Line Inc. (IPL) 864-millimetre (mm) outside diameter (nominal pipe size (NPS) 34 inches) main crude oil pipeline, designated as Line 3, suddenly experienced a simultaneous loss of operating pressure and increase in crude oil flow rates at both the Glenavon pump station, Mile Post (MP) 504.722, and at the Langbank pump station, MP 543.839, located near the towns of Glenavon and Langbank, Saskatchewan. The Control Centre Operator (CCO), located in Edmonton, Alberta, remotely operates the Glenavon and Langbank pump stations 24 hours a day, 7 days a week. These two pump stations are normally unmanned. At 0620, from the control console in the Edmonton Control Centre (ECC), the CCO initiated an emergency pipeline shutdown of Line 3 for all the IPL pump stations from Hardisty, Alberta (MP 109.019), to its associated facilities located at Superior, Wisconsin, U.S. (MP 1097.372). The net effect of the CCO's command would stop the movement of crude oil by shutting down pipeline facilities on Line 3. At 0624, the ECC notified the Royal Canadian Mounted Police (RCMP) of the suspected leak in the Glenavon-to-Langbank area of the pipeline system. At 0626, the CCO issued close commands to the remotely operated sectionalizing valves located at Odessa, Saskatchewan (MP 473.479), and Langbank. At the same time, close commands were issued to the remotely operated sectionalizing valves located at MP 504.860 and MP 543.980. At 0629, all these valves were confirmed closed by IPL's Supervisory Control and Data Acquisition (SCADA) system. At 0630, Line 3 was confirmed closed by the SCADA system. At 0638, IPL's Central Region management was notified of the suspected leak. At 0640, IPL's Pipeline Maintenance Supervisor was notified of the occurrence, and deployed verifiers and containment personnel from IPL's Regina and Glenavon pump stations. At 0845, company employees located the occurrence site at MP 506.6830, approximately 3 km downstream of the Glenavon pump station. They then proceeded to secure the occurrence site. The closest sectionalizing valve upstream of the rupture site is located at the Glenavon pump station, which had been remotely closed earlier by the CCO, thus restricting the amount of crude oil that would drain down. The nearest sectionalizing valve downstream of the site was a manually operated valve located at MP 531.0, which had not been closed. Due to the elevation profile of the pipeline at this valve location, IPL decided that this manual valve did not need to be 1 All times are mountain standard time (Coordinated Universal Time (UTC) minus seven hours) unless otherwise stated. TRANSPORTATION SAFETY BOARD 1 FACTUAL INFORMATION closed to prevent an unnecessary drain-down of crude oil into the occurrence site. The next closest sectionalizing valve downstream of the rupture site is located at the