The Dutch Safety Board has published an investigation report into an incident in which a fatal accident occurred on board the cruise ship Nieuw Amsterdam following the failure of a bellows-type expansion fitting in the steam pipes.
The incident
At about 09.15 hours local time on the morning of 22 March 2024, a fatal accident occurred on board the Dutch cruise ship Nieuw Amsterdam when it was calling at Half Moon Cay in the Bahamas. In an area of the engine room, an expansion joint in the main steam pipe ruptured. Through the resulting hole in the steam system, the room quickly filled up with steam at a temperature exceeding 100 °C.
The steam was released on the port side, while two crew members were working in the same room on the starboard side. Because the vessel was not alongside the quay, the doors at the forward and aft of this room were closed in accordance with the procedure.
Due to the speed with which the room filled up with the hot steam, the two crew members could no longer reach the doors and the emergency exit and sustained fatal injuries.
Rupture of the expansion joint due to steam hammer
Due to steam hammer in the steam system, the steam pipe ruptured in a weak spot: the expansion joint. The rupture in the expansion joint was large enough to fill up the forward sewage room rapidly and entirely with steam.
Maintenance prior to the occurrence
The steam hammer occurred because a valve that was normally left slightly open had been fully closed. This was done on 17 March 2024, ahead of the repair of one of the heaters in the steam system. The crew involved knew that the valve was normally slightly open in order to keep the pipe warm, but they did not know that the act of closing the valve turned the pipe with the expansion joint into a dead end where condensate could build up. If condensate builds up, it can flow back against the direction of the steam. The steam then re-heats this water, turning it back into steam. As a result, the volume suddenly increases significantly, causing dangerous peaks in pressure (steam hammer). None of the crew members were aware of the danger of the build-up of condensate in this part of the steam piping.
Steam heaters not in use, but not fully closed either
During normal operation, the steam heaters were not in use (except for a few days a year). However, this did not mean that all steam heater valves were fully closed. The necessity of keeping the valves slightly open was not covered in the work procedures on board. Consequently, the risk of the build-up of condensate as a result of closing the steam inlet pipe fully was not covered in the Lock Out Tag Out procedure, nor in the risk analysis for steam system maintenance.
Steam hammer not covered by training or instruction
The crew did not receive any training or instruction regarding the causes, dangers, and prevention of steam hammer. The owner’s internal training and instruction regarding the steam system procedures are in line with international legislation and regulations. The legislation and regulations do not mention the risk of steam hammer in a steam system. In both the internal training and instruction and the procedures on board, the risk of the build-up of condensate and hence the risk of steam hammer was assumed only to be present during the procedure to start the steam system (or parts of it).
Design versus use of the steam system
The design of the steam system did not account for the possibility that part of the system was not in use. In practice, this meant that the valves in the branch to port were not fully closed in order to prevent the build-up of condensate. Because a valve could be closed by mistake, this method raised the risk of steam hammer.
Recommendations
Prevent structural workarounds in steam systems
During normal operation of the steam system on board the Nieuw Amsterdam, a structural workaround was necessary (a valve was kept slightly open) to prevent condensate build-up in the system. Although a workaround is sometimes unavoidable in practice, its prolonged use should be avoided.
Recommendation to Holland America Line (HAL)
To promote the elimination of structural workarounds in steam systems on HAL vessels, the Dutch Safety Board recommends the following to the HAL:
- Check all your existing ships to determine whether structural workarounds are being used in the steam system during normal ship operations. If a structural workaround is found, the system or procedure should be modified so that the crew no longer needs to use the workaround.
Recommendation to NMT-IRO23
To prevent steam systems that require the structural use of a workaround from being installed in new ships, the Dutch Safety Board recommends the following to NMT-IRO:
- Draw your members’ attention to the need to avoid installing steam systems in new ships that require the structural use of a workaround during normal ship operation.
Recommendation to the Royal Association of Netherlands Shipowners (KVNR)
To ensure that other shipping companies can also learn from this incident, the Dutch Safety Board recommends the following to the KVNR:
- Draw attention to the need to avoid the use of structural workarounds in steam systems among your members and international contacts.
Improve crew awareness of the risks of condensate build-up and steam hammer in steam systems
The crew aboard the Nieuw Amsterdam had limited knowledge of the risks of condensate build-up and steam hammer in steam systems. These risks were not addressed in procedures and training. Crew training also pays little attention to these risks.
Recommendation to Holland America Line (HAL)
To increase crew knowledge and awareness of the risks of condensate build-up and steam hammer in steam systems on HAL ships, the Dutch Safety Board recommends the following to HAL:
- Amend your procedures and training regarding working with steam systems so that crews are better aware of the risks of condensate build-up and steam hammer.
Recommendation to the Minister of Infrastructure and Water Management (I&W)
To incorporate the risks of condensate build-up and steam hammer in steam systems into seafarer training, the Dutch Safety Board recommends the following to the Minister of Infrastructure and Water Management:
- Submit a proposal to the International Maritime Organization to amend the Standards of Training, Certification and Watchkeeping for Seafarers (STCW) so that the risks of condensate build-up and steam hammer in steam systems are addressed in crew training. In anticipation of an amendment to the STCW, bring these risks and this case to the attention of maritime schools in the Netherlands, so that they can already address them in their education.
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Source: Dutch Safety Board
