ANCHORAGE — Hot material left behind by a welding crew likely started a fire last year that caused as much as $750,000 damage to the Alaska state ferry Malaspina, according to the National Transportation Safety Board.
The 372-foot vessel was undergoing repairs at Alaska Ship and Drydock in Ketchikan when the fire broke out. No one was injured.
The fire was extinguished by the Ketchikan Fire Department and investigated by the department and the Coast Guard, which passed on their findings to the NTSB.
The agency determined that the welding crew improperly used a welding curtain meant to be installed vertically to shield against sparks.
Instead, the report concluded, the curtain was installed horizontally. Molten material burned through the curtain and fell into a room below. The hot metal ignited flammable materials, lighting a fire that was not immediately discovered because crew members had left for their lunch break.
“The National Transportation Safety Board determines that the probable cause of the fire on board the passenger vessel Malaspina was the failure of the shoreside work crew and fire watch to ensure that proper cooling had occurred before leaving the area where the repair work was conducted,” the report said.
Alaska Ship and Drydock’s director of shipyard development, Doug Ward, said Monday the company agreed with the assessment.
“The report was factual,” he said. “We can’t argue with that.”
The company’s insurance covered the cost of the damage and the company brought in extra workers to repair damage from the fire and complete the original contract work.
“There was no delay to the ship going back into service,” Ward said. “We understand how important it is to keep the ferries running on their published schedules,” he said.
The Malaspina, which was built in 1962, can carry up to 499 passengers and a crew of 50. It has 73 staterooms and can carry 88 vehicles.
A work crew on Feb. 7, 2012, had come on board to repair a ventilation duct in a crew member stateroom located just above the vessel’s sewage treatment room.
The open ventilation duct exposed the sewage treatment room to the stateroom, and workers covered the opening with the welding curtain to collect slag, the waste produced by high-temperature metal work, according to the report.
Just before noon, welders and the fire watch worker broke for lunch, and as they left the Malaspina, smoke started pouring out of the sewage treatment room.
Investigators determined that the curtain could not withstand continuous contact with the hot metal and the slag burned through and fell into the lower room, igniting combustible material. If workers had remained on board to make sure materials had cooled, the report said, they would have detected flames while they were small.
Ward said the accident occurred weeks before the shipyard was sold to Vigor Industrial. The company analyzed the accident and instituted changes that require crews to stay at the job site until 30 minutes after the last weld or until temperatures in a fire watch area have returned to ambient temperatures. That means looking for hot spots left by welders.
The company has also increased training, Ward said.
Getting the state ferry back in the water on schedule was important to the shipyard, he said.
“The Marine Highway System is certainly one if not our most continuous and best customers,” Ward said. “We like to make it easy for our customers to come back.”