Winnipeg Free Press

Winnipeg Free Press (Newspaper) - August 2, 1995, Winnipeg, Manitoba B Winnipeg free press August 1995 inside Story pipe a ticking time bomb Tran Canada pipelines both ohcs weekends weekdays get the Best weekend news delivered to the cottage keep the Best weekday news delivered to your Home or office if you had thought that it would be a hassle having to Stop and Start delivery of the paper when youre going to be away for the we have the answer the Winnipeg free press has introduced a new no hassle monday to Friday delivery for Only per week in simply Call and Tell us which weeks you will be away for the weekend and we will make sure that you Only get the paper monday to we can also arrange for delivery of the saturday and sunday papers to your cottage if you Are in a delivery this subscription would be paid to your local cottage area convenient delivery and All the news everyday wherever you 697700 per week monday to Friday s convenient offer Winnipeg free press All color repairs hasten breakdown of Gas lines study Bald Santin staff reporter the bulk of Canadas natural Gas pipeline system is a tick ing Tirrie bomb that can go off at any time a study by the transportation safety Board concluded the report says conditions that led to saturdays fireball explosion at rapid City exist throughout the entire Tran Canada pipeline the which was initiated of Ter three ruptures in North Western Ontario during a 19month period 1991 and found that the coatings applied to the pipelines Between 1958 and 1983 Are susceptible to breakdown and can contribute to cracking in the exterior Wall of the pipes that can Lead to a leak or the report said the Only hopeful sign was that a new coating used since the late 1980s is More resistant to but Only time will Tell How effective it the report found that engineering studies and the pipelines own maintenance program that Short of replacing suspected sections of weakened pipe or actual cracked existing testing and repair methods Only hasten the deterioration of the pipe and almost guarantee future leaks or expo company officials Are blaming the rapid City explosion on a recently discovered stress corrosion stress corrosion cracking involves the formation of hairline cracks in the outside Walls of the its caused through a Combina Tion of stress on the Wall from the Gas flowing through the Brittle Ness of the pipe Wall and corrosive soil the safety Board report of August 1994 states that despite the obvious concerns Over pipeline testing and repair methods for stress corrosion there Are no Federal regu lations or Good working practices governing appropriate testing and repair the pipeline occurrence report Tran Canada pipelines limited natural Gas pipe line ruptures said that stress corrosion cracking was responsible for the three ruptures in Northern on the cracking first appeared in the system in that discovery prompted the company to examine Many of its pipelines East of Winni in 500 Crews uncovered More than sets of cracks on the the report states that pipeline officials did not conduct any examinations of its pipelines West of Winni Peg because it didst believe the sys tem was susceptible to cracking As Western soils Are less Cor that policy was maintained de spite a pipeline leak in Brandon in after last weekends explosion at rapid officials said the com Pany would now begin checking its pipeline West of the report found most repair methods actually make the pipe More Brittle and weaken the entire exterior causing stress Corro Sion to develop since the company maintenance program has resulted in 25 pipeline ruptures 15 of those rup Tures were caused by stress Corro Sion cracking hastened by repair when cracks Are found that Are longer than 10 Millimetres and More than 10 per cent of the Wall then the entire area is ground if safety regu common r Between Janu three blew Tran limited t ground and was i Flo i of Board All three Ruitu corrosion pipe were bib on pipe were blown out of the there was no no on july near metres of pipe were blown out of the there was a there were no a Tab analysis of the three ruptures found Cpl began a pipeline maintenance program in 1986 but restricted it to Only two of its six lines a portion of a line Between Winnipeg and and a portion of another line Between Toronto and the maintenance program caused 25 ruptures of the pipeline 15 of these were j attributed to stress corrosion to cps Pip testing method hydrostatic retesting weakens the pipe and hastens the stress corrosion to cps current method of repairing cracks in the outside Walls of pipes surface grinding with a handheld grinder encourages further cracking and May mask deeper there Are no regulations or guidelines for the appropriate and Safe monitoring and repair of stress corrosion source commodity pipeline occurrence transportation safety Board of 1994 cracks spread stress corrosion cracking is a progressive fracture in a pipeline that is caused by the pressure from the Gas inside the pipe and corrosion from the a Lone crack is insignificant but cracks can occur in Over those grow and Combine with adjacent cracks to form a critical crack where a leak or rupture will hydrostatic retesting is a method used to test the internal pressure of the pipe is increased far beyond recommended safety the rationale is that if the pipe Doest rupture under these then its unlikely to rupture at Normal pressure magnetic particle inspection is a technique to measure the depth of cracks in the its usefulness is questionable because its findings Are subject to interpretation by the blast further flaws Are found that part of the pipe is but studies have shown that the High temperatures created during the grinding make the pipe More which increases the spread of stress corrosion in other so much of the pipe material is replaced through the grinding work that the pipe is weakened to the Point where it later ;