Start with the exact cargo description
“Wood pellets” is not enough detail to build an operating plan. The IMSBC schedules distinguish pellets containing additives or binders from those that do not. Confirm the cargo description against the shipper’s information and the applicable schedule before agreeing the handling and monitoring arrangements. The distinction matters: the schedules describe different hazards, including different cautions about fermentation and fire risk.
For pellets without additives or binders, the schedule identifies oxygen depletion and rising carbon monoxide and carbon dioxide in the cargo and communicating spaces as hazards. It also warns that moisture can cause swelling and that fermentation may occur over time above 15% moisture content; the schedule says the resulting gas concentrations do not reach flammable levels for this cargo. The US Coast Guard’s alert, by contrast, concerns pellets containing binders and describes fires in barges where moisture, cargo decay, elevated temperatures and gases were observed. Treat those findings as a warning about that cargo and incident—not as a substitute for identifying the shipment actually aboard.
The practical first step is to align the cargo name, composition information and applicable schedule with the shipboard plan. If the cargo details do not clearly resolve which schedule applies, resolve that before loading rather than assuming all pellet cargoes behave alike.
Amendments to the International Maritime Solid Bulk Cargoes (IMSBC Code) of the International Convention for the Safety of Life at Sea · USCG Safety Alert 10-23: Wood Pellet Fire Hazards
Keep moisture out from the first pour
Moisture control is an operational measure, not just a cargo-quality preference. The IMSBC schedule for pellets without additives or binders says to keep the cargo as dry as practicable, not to handle it during precipitation, and to close non-working hatches serving the holds being loaded. It also warns that pellets may swell if exposed to moisture. Build those requirements into the loading conversation: identify who calls a weather stop, how exposed cargo and openings will be protected, and how the decision to resume will be communicated.
The USCG alert recommends isolating binder-containing pellets from external moisture, including stopping cargo operations during inclement weather and maintaining covers against rain ingress in transport. The alert also describes moisture, visible cargo decay and discoloration among conditions found on affected barges. These observations make a useful inspection prompt, but they are not a universal diagnostic test: visible condition alone does not establish the atmosphere or temperature inside a hold.
Dust deserves attention during loading and cleanup as well. The schedule warns that handling pellets may generate dust and that high dust concentrations can present an explosion risk. Keep the agreed controls practical for the transfer method and the work being done, rather than treating a clean-looking hatch opening as proof that dust exposure is controlled.
Amendments to the International Maritime Solid Bulk Cargoes (IMSBC Code) of the International Convention for the Safety of Life at Sea · USCG Safety Alert 10-23: Wood Pellet Fire Hazards
Make atmosphere checks part of access control
A hold containing pellets can become oxygen-depleted while carbon monoxide accumulates. The UK Health and Safety Executive describes this hazard in ship holds and adjacent spaces, and notes that spaces can remain dangerous even after cargo has been loaded for some time. A ventilated hold or an apparently separate adjacent space should not be treated as safe by assumption.
For pellets without additives or binders, the schedule states that personnel must not enter cargo or adjacent confined spaces until tests establish oxygen at 21% and carbon monoxide below 100 ppm. It calls for an oxygen and carbon monoxide meter to be worn and activated by crew entering cargo and adjacent enclosed spaces. If the stated conditions are not met, the schedule calls for additional ventilation and repeat measurement after a suitable interval. Follow the ship’s enclosed-space procedures as well; do not turn a single reading, open hatch or informal check into entry permission.
Plan this control before the need arises. Include adjacent spaces in the access discussion, identify how ventilation and re-testing will be managed, and brief crew and relevant shore personnel that an entry request is a stop-and-check point. The schedule specifically notes that adjacent spaces may need ventilation before entry even if they appear sealed from the hold.
Amendments to the International Maritime Solid Bulk Cargoes (IMSBC Code) of the International Convention for the Safety of Life at Sea · Wood pellet bio-fuel
Carry the plan through the voyage and discharge
The schedule warns of renewed oxygen depletion and carbon monoxide formation in previously ventilated adjacent spaces after hatch covers are closed. That makes the end of loading a handover, not the end of the atmosphere risk. Record the cargo identity, hold and adjacent-space precautions, and the agreed route for communicating observations or abnormal findings so the next watch and the discharge team receive the same picture.
The USCG recommends routine temperature readings and frequent rounds to look for signs of smoldering for owners and operators of hopper barges carrying wood pellets. On a ship, use the applicable cargo schedule and vessel procedures to decide what monitoring is appropriate; the alert’s recommendations should not be mistaken for a universal monitoring rule for every vessel. If observations such as unusual heat, decay, discoloration or smoke raise concern, escalate through the vessel’s emergency and company procedures rather than sending someone into a space to investigate.
Before discharge or cleanup, repeat the access-control discipline for the spaces people may need to enter. A cargo transfer can change which openings are accessible, but it does not itself prove the atmosphere is safe. Keep the cargo’s identity, moisture precautions and atmosphere controls connected from loading through the final work in the hold.
Amendments to the International Maritime Solid Bulk Cargoes (IMSBC Code) of the International Convention for the Safety of Life at Sea · Wood pellet bio-fuel · USCG Safety Alert 10-23: Wood Pellet Fire Hazards