WATER HAMMERING DUE TO IMPROPER DRAINING OF WATER :
The ship arrived in port to discharge oil. The ship had a boiler, the secondary drum pressure was 17.5 bar. Before opening the steam stop valve the steam lines of the cargo pumps were drained. The junior engineer, opened the drain valves fully thinking that the water will drain faster. He shut the valves when he did not see any water coming out of the drain. He then started opening the main steam stop valve of the secondary drum. He must have opened it little more instead of crack opening, the water hammering started heavily. He got scared about the sound and he shut the valve and ran out of the boiler quickly. In a few seconds, the main steam stop valve blasted into pieces and the entire boiler space was filled up with steam. Alarm was raised and the senior engineers came and took over the situation. Luckily the junior engineer escaped without any injury.
when working on steam lines, before opening the steam, it is very important that the entire system is drained off cold water by opening the drain valve very little. Also while opening the steam stop valve, open it crack and wait for sometime till the line is getting warmed up, and any water trapped can be pushed back to the hot well.