Injury from burst hydraulic valve
On a cargo vessel in drydock, the crew was testing the operation of an electro-hydraulic mooring winch after completion of repairs. The team, led by the C/E, and comprising of the 3/E, J/E and an OS, entered the hydraulic machinery room and started the main pump motor. Without warning, the return line gate valve before the filter disintegrated and the detached bonnet flew through the air, hitting the J/E on his face and fracturing his skull and nose. He was immediately hospitalised ashore. Very fortunately, he narrowly escaped more serious injury that could have resulted in permanent damage to the eyes and brain and was able to recover fully from this accident.
Result of investigationDuring an earlier trial, it was noticed that one of the valve flanges next to the filter was leaking. After isolating the line, the crew renewed the gasket, and then opened the valve before the filter, but forgot to open the one after the filter. When the pump was subsequently started, the sudden build up of high pressure on the upstream side of the valve resulted in its violent disintegration.
Lessons learnt1 It is extremely important that, before commissioning hydraulic systems, all line valves are verified to be fully open and the system is thoroughly purged of air and primed with the correct quantity/type/grade of hydraulic fluid;
2 Return lines are not designed to take high pressure in most hydraulic systems.
Corrective/preventative actions1 The second valve (after the filter) was considered redundant. It was removed and replaced with a spool piece, reducing the risk of the inadvertent closure of the return line;
2 A sign was permanently installed next to the hydraulic pump motor starting switch warning personnel to ‘Ensure all return line valves are fully open’.
Result of investigationDuring an earlier trial, it was noticed that one of the valve flanges next to the filter was leaking. After isolating the line, the crew renewed the gasket, and then opened the valve before the filter, but forgot to open the one after the filter. When the pump was subsequently started, the sudden build up of high pressure on the upstream side of the valve resulted in its violent disintegration.
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Lessons learnt1 It is extremely important that, before commissioning hydraulic systems, all line valves are verified to be fully open and the system is thoroughly purged of air and primed with the correct quantity/type/grade of hydraulic fluid;
2 Return lines are not designed to take high pressure in most hydraulic systems.
Corrective/preventative actions1 The second valve (after the filter) was considered redundant. It was removed and replaced with a spool piece, reducing the risk of the inadvertent closure of the return line;
2 A sign was permanently installed next to the hydraulic pump motor starting switch warning personnel to ‘Ensure all return line valves are fully open’.
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