Transport Malta MSIU issued an investigation report on the serious injury of a crew member during tank cleaning operations, onboard the Sichem Manila, while at Tarragona anchorage, Spain. The crew member was spilled with hot water while shutting off a valve. The investigation established that mild steel bolts holding the valve block and the valve bridge were heavily corroded.
The incident
On 17 February 2020, whilst Sichem Manila was on anchor, several crew members were engaged in cargo tank cleaning operations.
During the process, while one of the crew members was shutting off a valve on the cargo tank cleaning line, the block of the valve burst open, spilling hot water over him.
Tank cleaning operations were immediately suspended, and the injured crew member was transferred to the vessel’s hospital where first aid was administered. Eventually, he was transferred to a local hospital for further treatment.
Probable causes
The Marine Safety Investigation Unit (MSIU) concluded that the cause of the valve block failure was either a high-pressure stream of water or a water hammer effect, acting on the corroded mild steel securing bolts of the valve block.
Conclusions
- AB 1 suffered second and third-degree burns following the failure of the block of a branch valve, which burst open whilst the injured AB was shutting it, causing hot sea water at 75 ℃ to spray onto him.
- Neither was the valve block nor the valve damaged due to this occurrence.
- The mild steel bolts holding the valve block and the valve bridge were heavily corroded, possibly due to a galvanic reaction with a dissimilar metal.
- The corroded bolts may have ruptured after a pressurized stream of hot water was directed onto the part of the block in the vicinity of these bolts, causing the valve block to burst open.
- It was not excluded that a water hammer effect may have developed when the valve was shut, resulting in the rupture of the corroded mild steel bolts of the valve block.
- It is highly likely that the material of the bolts, as well as their corrosion, was not noticed by the crew members due to the paint coating covering them.
- The PPE worn by the injured AB did not protect him against the hot water spray.
Actions taken
During the safety investigation, the company took the following measures to prevent similar accidents onboard its vessels:
- All bolts on the Sichem Manila’s cargo tank cleaning line were checked and replaced, as necessary, with stainless steel bolts.
- All vessels under the Company’s management were instructed to check the fittings of their respective cargo tank cleaning lines.
- All serving masters were instructed to record the pre-operation checks of the cargo tank cleaning system in the deck logbook.
- The planned maintenance system of the company’s vessels was revised to include the inspection of the tank cleaning line and bolts during the company’s recommended annual pressure test of the tank cleaning line.
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