MAC has previously drawn attention to the hazards of wood pellets, only added to the IMO’s Code of Safe Practice for Solid Bulk Cargoes , the BC Code, in 2005, BIMCO is also expressing concern about these hazards.
Says a BIMCO alert: “Although two investigations were carried out on the carriage of wood pellets, no intensive literature has been produced. Therefore, the information below is based on comments obtained generally regarding this commodity.
Wood pellets, produced from sawdust and wood shavings containing no additives or binders are not the same as wood pulp pellets, which are made of compacted wood chips. The shipment of wood pellets carries with it two main hazards: combustion hazards and carbon monoxide emissions.
Due to transport movement and physical handling of the pellets, some pellets are broken and the whole shipment of the cargo tends to come in a mixture of pellets, pieces of broken pellets and wood dust. Note that not only are wood pellets subject to combustion when ignited, the wood dust generated by the pellets can also give rise to a dust explosion when it is dispersed and ignited under certain conditions of containment.
It is also worth noting that combustion can similarly occur when stored bulk piles of wood pellets can self-heat in parts with high moisture content, leading to spontaneous combustion of the cargo after a long period of time.
Wood pellets are also subject to oxidation, leading to depletion of oxygen and production of carbon monoxide and carbon dioxide. Because carbon monoxide is toxic and flammable, the hazards associated with oxygen depletion and generation of carbon monoxide should be closely monitored especially in a closed space e.g., unventilated cargo holds. It is now common practice by stevedores to hire “gas doctors” to examine spaces that carry wood pellets or have carried such cargo. It is also advisable that carriers follow the requirements of the BC Code for carriage of wood pellets when contemplating such shipment.