The Nig Creek pipeline, about 40 kilometres northwest of Buick in the northeast Interior, ruptured last June, and caused a fire to spread to surrounding forests.
The fire also caused a Bonavista Energy Corporation pipeline nearby to rupture as well.
The TSB investigation finds that pipes made using a certain welding technique increase the chances of defects such as cracks and raises the risk of a pipe failure.
Westcoast Energy was told by the National Energy Board to make necessary repairs, and it has scheduled various inspections and reviews of the pipeline.
The board says it expects that any changes that result from the company's assessments will lead to better emergency response times in the future.
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