The Republic of the Marshall Islands (RMI) Maritime Administration has released an investigation report into two enclosed spaces deaths on board drill ship Valaris DS-17.
What happened
On 21 April 2023, the Republic of the Marshall Islands-registered drill ship Valaris DS-17, managed by ENSCO International Inc., was alongside in a shipyard at Las Palmas, Canary Islands, Kingdom of Spain. The ship was scheduled to depart Las Palmas on 1 May 2023. Work that needed to be completed prior to the ship’s departure included cleaning the BWT.
The BWT had to be mechanically ventilated for at least 24 hours before it could be entered by a cleaning crew. In preparation for starting mechanical ventilation, the ship’s 2/E No. 1 and a Motorman opened the BWT starboard access hatch. The hatch was located on the tank top beneath the deck plates in the No. 1 Aft Pump Room and was accessed by climbing down a 1.5 m vertical ladder.
After opening the access hatch, the Motorman climbed up the vertical ladder to the deck plates. The Motorman, who had stepped from the ladder onto the deck plates, saw that the 2/E No. 1 had stopped climbing up the ladder and laid his chest on the deck plates. The Motorman grabbed hold of the 2/E No. 1’s coveralls and yelled for help. A third-party electrician who was working in the No. 1 Aft Pump Room responded. Within seconds of the third-party electrician reaching the scene, both the 2/E No. 1 and the Motorman, who was kneeling on the deck plates while holding onto the 2/E No. 1’s coveralls, fell through the open access hatch into the BWT. The third-party Electrician immediately informed crewmembers who were in the Engine Control Room and the alarm was raised.
Members of the ship’s rescue team reported smelling what was described as a “strong smell of rotten eggs” when they entered the No. 1 Aft Pump Room to initiate an enclosed space rescue. Neither the 2/E No. 1 nor the Motorman were breathing or had a pulse when they were removed from the BWT by members of the ship’s rescue team. Efforts to resuscitate the 2/E No. 1 and the Motorman were unsuccessful, and they were determined to be deceased.
The investigation
The marine safety investigation conducted by the Republic of the Marshall Islands Maritime Administrator (the “Administrator”) determined that the PTW for opening the BWT access hatch was not issued in accordance with the Company’s established procedures. Though portable gas detectors were available on board, one was not available on-site as required by the Company’s relevant Work Instructions when the 2/E No. 1 and Motorman opened the BWT access hatch. The Administrator’s investigation also determined that physical access to the BWT access hatch was restricted, which increased the risk of exposure to any gases that were within the BWT ullage space after the hatch was opened and while climbing the ladder up to the deck plates. The investigation further identified that the crewmembers were aware the atmosphere in the BWT ullage space contained hydrogen sulfide but that they may not have been aware that it could potentially contain high concentrations of hydrogen sulfide.
Lessons learned
The lessons below were identified:
- Administrative controls, such as PTWs and Work Instructions, must be implemented consistently and in accordance with established procedures to be an effective means of reducing exposure to hazards.
- The importance of identifying connected spaces and their hazards.
- The importance of identifying and addressing hazards associated with the location where the work will be conducted when planning a job.
- The importance of being aware that, when opening access hatches, tanks may contain higher concentrations of hydrogen sulfide, or other toxic gases, than might be expected.
Read the full report: RMI VALARIS-DS-17 Casualty Investigation Report