The latest edition of TT Talk discusses the risks of poisonous vapours in enclosed cargo holds
No-one involved in working on board an oil, gas or chemical tanker at sea or in port, states TT Talk, would remotely consider entering a tank on board without all the appropriate precautions being taken before and during entry, often also associated with a “Gas-Free Certificate” and a “Permit to Work."
However, continues the TT Talk article, it would seem that the same safety awareness and the need to take appropriate precautions, amongst both shipboard and shore side personnel, is not present when it comes to general cargo, bulk and container ships.
Many spaces on cargo ships are readily considered to be “enclosed”, such as ballast tanks, void spaces, cofferdams, double bottoms and fuel tanks, so suitable precautions are generally therefore taken. On the other hand, cargo holds are often not considered to be enclosed or confined spaces.
The problem is many sorts of cargo can emit hazardous vapours and fumes and others can deplete the oxygen content in the hold or space, below or above concentrations that are required to sustain life. Additionally, the trunkways and accesses to them, when not properly ventilated and checked for suitable atmospheres, have also resulted in fatal incidents.
In early 2017, the Hong Kong Marine Department issued an information note reminding personnel involved of the dangers, and steps to take before entry, following a multiple fatality related to a ship discharging semi-coke.
Two stevedores and a bulldozer driver died in the access trunkway to the cargo hold. Investigations established that the trunkway had not been ventilated sufficiently or the atmospheric conditions tested prior to entry, and the space was oxygen deficient.
This cargo is not the only one that can deplete the oxygen, and worse, replace it with denser than air vapours that sit at the bottom of such spaces. Coal and its derivatives, scrap metal, timber (especially with bark on logs), fishmeal, grains, DRI and bio-mass all potentially have such properties. Many bulk and other cargoes are also fumigated.
In the Hong Kong incident, the access way was also marked with signage saying, “Ventilation Before Entry” and “O2 Depletion”, but the warnings had been ignored by the stevedores before they climbed down the ladder. This might also indicate that appropriate training of all involved is insufficient.
This is not a new problem, states TT Talk. There have been many similar incidents, with single or multiple casualties involved so why are we not learning the lesson? It is certainly not for lack of information. UKP&I Club, TT Club and ICHCA have all published work dealing with risk avoidance.
Ships comprise a shared workspace; all entities involved must share information and establish who is in control. Key elements for any risk assessment prior to activities that might affect the health and safety of personnel should include:
"Normally it would be for someone with responsibility on board the ship to declare the space safe to enter. Be careful though; such a declaration was made a few years ago on a ship loading biomass in South America. Operations were suspended whilst the ship went back out to anchor. When it re-berthed a day later, the first stevedore down the ladder was asphyxiated."