TIGHTER SAFETY RULES URGED FOR CANADIAN PIPELINES

Canada's Transportation Safety Board (TSB) has urged tighter federal control of Canadian pipeline operations.

The board issued a set of recommended steps to improve pipeline safety as a result of its probe of a propane line rupture that occurred early in 1991 in Saskatechewan.

If adopted by the National Energy Board, one of the recommendations could require periodic retests and recertification of all Canadian high pressure pipelines under federal jurisdiction. The goal is to ensure the physical integrity of the country's pipeline system.

NEB's annual report lists 55 hydrocarbon liquids and natural gas pipelines under federal jurisdiction. They include long distance systems that move hydrocarbons from western Canada's sedimentary basin to markets in the U.S. and eastern Canada.

WHAT HAPPENED

TSB's probe involved a Petroleum Transmission Co. (PTC) pipeline rupture that occurred Jan. 9, 1991. Site was in section 29 15 5w2 near Broadview, Sask.

Built in 1963, the line runs from Empress, Alta., to Winnipeg, Man., near TransCanada PipeLines Ltd.'s natural gas pipeline. PTC's line runs adjacent to major highways, railways, an Indian reservation, add a number of towns.

The board found that the PTC line failed at a defective weld on a longitudinal seam as a result of long term internal pressure fluctuations. About 791,000 l. (208,824 gal) of propane were released to the atmosphere through a 25 cm (9.8 in.) split in the seam. The weld defect had existed since the pipe's manufacture, TSB said.

At about 5:45 p.m. CST on the day of the occurrence, PTC's control and data acquisition system began providing many computer messages and audible warnings for operator was a problem on the line.

However, TSB said, control center personnel overrode those alarms. And only after a shift change did emergency response procedures get under way. Meantime, large volumes of volatile material escaped into the air.

"It is not clear why the operating personnel did not verify the deficiency or initiate precautionary, measures," TSB said.

"This accident calls into question the adequacy of PTC's emergency response procedures. The extent of the accident and the amount of liquid hydrocarbons released were not communicated so a warning could be issued to the public. Furthermore, there were significant delays in alerting the Royal Canadian Mounted Police and local residents."

The board found it took four attempts by the emergency response team to ignite the propane vapor plume. PTC's emergency, response manual does not specify the number of times ignition is to be attempted when flaring a vapor hydrocarbon plume without reevaluating the area. Also, the manual does not specify procedures to be taken to ensure continuous site safety before each flaring attempt.

PTC experienced 123 pinhole leaks between 1965 and 1992, and since 1970 there were six long seam failures during normal operations, TSB said.

The board believes the occurrence record draws into question the condition of pipelines' longitudinal electric resistance weld seams.

TSB RECOMMENDATIONS

Based on its investigation of the PTC rupture, the safety board recommended that NEB:

Review the records of manufacturing defects in the electric resistance weld seams of other pipeline companies and assess the risk of failures.
Depending on the outcome of the survey, TSB said, NEB may wish to require that all high pressure pipelines under federal jurisdiction be retested and recertified on a scheduled basis "to ensure the continuing integrity, of the pipeline system and all components throughout its operational life."
Evaluate the need for better quality assurance standards during fabrication, distribution, and installation of onshore pipe and pipeline components.
NEB does not have the same stringent requirements for quality assurance in its onshore regulations that it has in its proposed offshore pipeline regulations.
Require standard operating procedures for pipeline control rooms to include potential emergency situations.
At present, TSB said, there are no directives regarding shift change procedures, response to batch tracking, errors, or guidelines for overriding emergency, signals.
Audit policies, procedures, and operating practices of all federally regulated pipelines to help ensure that effective emergency communication to all first responders and affected parties is maintained during emergency situations.
Lack of effective, timely communications demonstrated by the PTC response team raises serious questions about the adequacy of current emergency response standards in the Canadian pipeline industry, the safety board said.
Ensure that emergency response manuals of federally regulated pipelines moving high pressure hydrocarbons clearly specify procedures to be followed when trying to ignite a vapor plume.