A seafarer was severely injured when he attempted to carry out maintenance work on part of a 13 bar high-pressure fire-fighting system on a fire-fighting tug. Before the incident, the seafarers had conducted maintenance work on the manifold on the other side of the vessel without any accidents. The assumption was based on the fact that the system was not pressurised.
During his maintenance routine, the seafarer tried to remove the brass blanking cap from a hydrant valve on a manifold of four valves fitted in parallel. Yet, the other three valves were checked ten minutes earlier and no problem occurred.
Continuing, the seafarer wasn't able to release the locking pawl by hand and assuming that it was stuck, he used multigrips to free it. The line was under pressure and when the 600 gram blanking cap came free it was expelled under pressure and struck the seafarer in the face causing severe facial injuries.
According to AMSA the contributing factors to the incident are:
- Inadequate safe work procedures for working on high pressure systems;
- Incomplete closure of both the butterfly isolating valve to the manifold and the hydrant valve allowed air to pass the valve seat and become trapped under pressure in the hydrant chamber;
- Lack of 3mm pressure relief holes in the hydrant blanking cap as specified in AS 2419.2-2009;
- Use of heavy brass hydrant blanking caps rather than lightweight alternatives;
- Turning directions for opening and closing of hydrant isolating valve were non-standard and opposite to that shown on the valve control;
- Isolating valve indicator was unclear and positioned out of operator’s line of sight;
- Although this incident could have been prevented through effective controls, the provision of pressure relief and securing arrangements for the cap would have protected the seafarer where those controls were ineffective.
AMSA continues on recommending that:
- Although SOLAS does not require pressure relief holes in blanking caps, AMSA strongly recommends that the requirement for 3mm pressure relief holes in hydrant blanking caps, as specified in AS 2419.2-2009—fire hydrant installations, be complied with;
- Blanking caps are also available in a lightweight plastic composite material, which would reduce impact forces should all other controls fail;
- The use of lightweight alternatives where appropriate;
- The fitting of securing chains or wires to blanking caps as specified in AS 2419.2-2009—fire hydrant installations. This is designed to prevent the loss of the cap.
Finally, even where pressure relief arrangements are in place shipowners, operators, masters, and crew are reminded to exercise care when operating with, and working on, any fire-fighting systems. Perform the necessary checks described in the vessel’s SMS to make sure that no part of the system is pressurised before working on it.