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.
Nenita Ship Grounding | Impacts: |
| Industry: Marine |
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On the 19th of November 2016, the Nenita bulk carrier suffered an engine failure whilst traversing through the Columbia River, eventually becoming grounded as a result of the reduction in engine speed and loss of steerageway.
The US National Transportation Safety Board deemed the failure to have likely been caused by the failure of a main engine cylinder cooling jacket. When examined after the accident, the Number 3 cylinder cooling jacket was found to be cracked on the main propulsion engine. It was reported that around 5-10 gallons of cooling water was being lost through this crack each minute. As a result, the high temperature alarm for the cylinder went off, meaning the temperature was above 95 degrees C (203 degrees F). This alarm caused an automatically initiated emergency shutdown which limited the main engine to below 30rpm.
The report by the US National Transportation Safety Board suggests that one reason for the cracking found on the Number 3 cylinder cooling jacket could be improper tightening of the bolts on the cooling jacket. Investigators were told by the ship’s technical manager that bolts were hand tightened using standard wrenches instead of being tightened to the required torque specifications. The condition of three of the four bolts removed from the cylinder showed signs of being installed using excessive torque. Over-torquing bolts can cause the threads to be stretched beyond their limits, distorting its shape, and causing the bolt to fail. This in turn could have led to the cracking found on the cylinder cooling jacket.
The accident resulted in damage to the bulbous bow and hull of the ship, with $4 million estimated to be the total cost of the accident.
Source:
https://www.ntsb.gov/investigations/AccidentReports/Reports/MAB1801.pdf