Why Following Correct Torque Procedures is Critical
Torque tools play a key role in ensuring safety and quality in a variety of industries. But these torque tools can only provide this quality when the correct torque procedures are followed. Click on the case studies below to read about what can go wrong when torque procedures aren’t followed correctly in a variety of industries.
Wenatchee Ferry Fire
One loose bolt caused $3.8 million in damages when it caused a fire aboard the Wenatchee passenger and car ferry on the 22nd of April 2021. The fire occurred during a sea trial in the Puget Sound on the coast of Washington, USA. No injuries were reported.
The sea trial was being conducted as a result of two of the four diesel engines aboard undergoing a full overhaul. It would be the second time the engines would run since the overhaul, having been run prior in February 2021.
During this February test, one of the overhauled engines started having low oil pressure problems, bringing a halt to the tests. During inspection of the engine, plastic debris of a cigarette lighter was found inside an engine valve. Roughly 70% of this debris was removed from the valve, which was deemed adequate to operate the engine as normal. The engine would not be started again until two months later.
Come the 22nd of April 2021, and it was time for the engines to be run again in a sea trial to see if the ferry was fully functioning. This trial was necessary to be completed before the ferry could return to normal operations. During the trial, engine power was slowly increased to 100%, and systems were being monitored for issues. It was approximately 5 hours into this test where one crewmember noticed white smoke next to one of the engines. They also observed “red glowing items that was just popping out of no. 4 (the main engine)”, which resulted in a fire within the engine rooms. Thanks to the fast and effective action from the thirteen crewmembers onboard at the time, the fire was put out in a little over an hour, and no one was hurt.
Upon surveying the engine room, the engineers discovered that a broken connecting rod, part of a piston and an inspection cover were laying on the ground. Within the engine, the crankshaft had part of a piston on top which had come free during the incident.
Initial assumptions put the blame on the lighter debris that remained in the engine from the February tests, but further analysis of the bolts from the engine showed that one bolt had worked its way loose during the test, as the result of inaccurate torquing during installation. This bolt then led to connecting rods and pistons being misaligned as the test went on, meaning parts of the engine lost lubrication and rose in temperature. This in turn meant that the items "popping out" of the engine were red hot and leaked gases from the engine, leading to the ignition of the fire.