Manitoba natural gas pipeline that exploded had pre-existing defect, report says

WINNIPEG – The Transportation Safety Board says a natural gas pipeline that exploded in Manitoba last year had a crack that formed at the time of its construction more than 50 years ago.

The federal agency launched an investigation after a TransCanada pipeline (TSX:TRP) near the southern Manitoba community of Otterburne ruptured on Jan. 25, 2014, allowing natural gas to escape and burn for 12 hours.

Five homes were evacuated in the area, located about 50 kilometres south of Winnipeg, but no injuries were reported.

The safety board says Line 400-1 ruptured due to a fracture that occurred at a pre-existing crack that had remained stable since its construction.

The board says the crack was likely due to an inadequate welding procedure and poor welding quality at a time when there was no requirement that every weld be inspected.

In its report, the board says the fracture was caused by incremental stresses to the pipeline which it attributes to factors including record low temperatures and weakened soil support in the area.

TransCanada says its current welding and testing processes are designed to locate small cracks like the one that led to this incident.