Crushing incidents have a particular sense of horror all of their own that needs no description. In the case of the fitter aboard the Bahamas-registered cruise ship Seven Seas Voyager he was left with serious injuries when a supposedly isolated ash dump valve closed on him, leading to hospitalisation for serious bruising and shock. He returned to the ship on light duties but two days later but continued to suffer from the effects of the incident and was discharged from the ship to recuperate at home for ten days.Ash grates on the vessel required replacement. Shortly after 0900, the fitter decided to see what the ash grate replacement involved. The open ash dump valve allowed him to access the grates.
Assuming that it was safe to start removing the grates, he began punching the taper pins holding the
grates. Unable to hit the punch squarely on the pin, he then stood up within the opening of the dump
valve and the deteriorated ash grates to get a better view. As he stood with his upper body inside the ash chamber, the fitter began moving the grates to better position them and punch the taper pins out.
When he moved the after grate to the fully closed position, the sensor switch signalled the ash
dump valve to close. The air to the valve’s operating system had been shut off but residual air in the
system allowed the valve to close against the fitter’s body. He did not notice the slowly moving dump valve until it was too late for him to get clear. As the valve closed on his lower body, he began to shout for help.
So why did it happen?
- Assuming that it was safe, the fitter accessed the incinerator’s ash chamber to replace its ash grates and inadvertently activated the electric sensor that automatically closed the ashchamber dump valve against his body.
- The ash dump valve’s electro-pneumatic control systems were not properly isolated and air
pressure in the valve’s operating system was not released, leaving residual pressure that
allowed the valve to close.
- The ship’s engineering staff did not have an adequate understanding of the incinerator’s
control systems and requirements of this specific task.
- The ash grate replacement task was undertaken on an opportunistic basis and not in
accordance with shipboard safety management system requirements and good work
practices. Consequently, the task was not adequately planned and risk assessed, and the
necessary permit to work and conditions required by the permit were not in place.
The risk of this sort of incident happening was increased by the fact that Seven Seas Voyager’s planned maintenance system, PMS, contained no information about waste incinerator ash grate replacement, a task that would have been periodically undertaken by different engineering staff since 2003. Therefore, in this respect, the shipboard procedures that documented requirements for the PMS had not
been effectively implemented; The manufacturer’s instruction manual for Seven Seas Voyager’s waste incinerator contained no specific instructions for ash grate maintenance or replacement. Such instructions would have provided useful information for the ship’s crew to plan and safely complete periodic ash grate maintenance.