In one of the bulk carriers, while doing cargo operations, it was observed that while giving the command for hoisting, it was found the hook going down (lowering operation)

Ship’s staff attended to the problem. Checked all hydraulic circuits and checked the filters and cleaned them. Control valve blocks were checked, and in the main valve block, some metal particles were found and they had scored the piston type valve. This had partially affected the movement of the piston valve and hence the hoisting operation could not take place.

The valve body and all parts cleaned, and the valve block had to be replaced, as the liner and piston valve had scoring marks. The spares had to come from Japan, and it took about a week’s time. Mean while the cargo work was carried out with the help of shore crane.The valve block was assembled after receiving the parts and tried out, the crane operated satisfactorily.The vessel was on a time charter, and the company lost its revenue partly on off hire.

Lessons learnt :

in any hydraulic circuits, it is imperative that maintenance should be of utmost order and the condition of the equipment has to be maintained to avoid such cargo delays and off hires. The system has to be kept absolutely clean and the filters have to be cleaned. Any metal particles or talon particles in the return line filter, indicates the wear and tear of hydraulic motors, pumps and valve blocks which should be attended to immediately.
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