202637 Wood pellet fires

As edited from USCG Safety Alert 10-23

Over a two-week span, two hopper barges loaded with wood pellets containing binders caught fire as a result of spontaneous combustion while awaiting transport at a fleeting facility (barge holding area). Each fire caused considerable damage, including total cargo loss and significant vessel damage. While spontaneous combustion is not common, it is also not unprecedented.

The International Maritime Solid Bulk Cargoes Code (IMSBC) notes that ‘wood pellets containing additives or binders may ferment over time if moisture content is over 15% leading to generation of asphyxiating and flammable gases which may cause spontaneous combustion’.

Assessment of other wood pellet barges revealed the presence of several hazards that can lead to spontaneous combustion, including:

• Visible moisture; Cargo decay and discolouration;
• Elevated cargo hold temperatures (75 C/168 degrees F);
• Carbon monoxide and hydrogen sulphide gas generated by cargo decomposition. Some of these conditions likely preceded both fires.

Unfortunately, the first identified hazard was visible smoke from already smouldering pellets. Heat from the smouldering cargo melted the hopper covers, introducing oxygen to a volatile situation, resulting in rapid and uncontrollable fire growth.

Lessons learned

• With such cargoes, take steps to isolate cargo from external moisture sources. These include ceasing cargo operations during inclement weather and maintaining hopper covers to prevent rain ingress during transport.
• Plan deliveries to minimise long term storage, particularly storage on board barges.
• Conduct routine temperature readings to detect early-stage cargo decomposition.
• Ensure personnel conduct frequent rounds to identify signs of smouldering.

As edited from USCG Safety Alert 10-23