A Norwegian LNG (liquefied natural gas) tanker, owned by Leif Höegh & Co, was under heavy refurbishment in Singapore. Close to completion of the work, a fire occurred during the final application of the tank insulation and TWI was called upon to ascertain the impact of the fire on the integrity of the 9%Ni steel tank.
The client's concern was that part of the tank would need to be replaced, and the ship would be further delayed from the schedule planned. Each day of delay was costing a substantial amount of money in lost revenue. Staff were rapidly mobilised from UK to meet the client's requirements and undertake on-site hardness testing and metallographic replication.
The hardness results were supplemented by microstructural replicas of regions where the fire was most intense and regions away from the fire source. The investigation showed that the 9%Ni steel and the associated weld metal was not significantly affected by the fire, and that the only remedial action necessary was to clean out debris from the fire, and replace the damaged insulation around the tank. Consequently the delay in return to service was limited to the time taken to reinstall insulation and therefore the financial impact was minimised. The vessel has now returned to active service.
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