NTSB Investigation: Fire aboard scrap metal barge
The National Transportation Safety Board (NTSB) has issued an investigation report regarding a fire on aboard scrap metal barge last May.
On May 23, 2022, about 0030 local time, the towing vessel Daisy Mae was towing the loaded, 300-foot-long scrap metal barge CMT Y Not 6 northbound in the Delaware Bay when a fire was discovered on board the barge.1 The fire burned for 26 hours before it was extinguished by responding fire boats. No pollution or injuries were reported. Damage to the CMT Y Not 6 was estimated at $7 million.
While underway in the open waters of Delaware Bay, the crew of the towing vessel Daisy Mae saw a fire in the scrap metal on board the barge 600 feet behind the towing vessel. The crew quickly notified their company management of the fire. They shortened the tow wire to the barge for better control and moved the vessel away from any marine traffic. Considering the Daisy Mae’s distance from the barge and need to keep the tow line attached to control the barge, the Daisy Mae crew took the appropriate steps to prevent and fight the fire.
The postcasualty inspection of CMT Y Not 6 revealed structural damage consistent with a high-temperature fire concentrated in the aft section of the barge. The scrap metal cargo in that area also exhibited signs of a high-temperature fire. The magnitude of the fire and the destruction of the cargo in the area where the fire was first identified prevented investigators from determining a conclusive origin of the fire. However, investigators found flammable nonmetallic materials, such as plastic, rubber, insulation, and electrical components, within the nondamaged cargo.
A spark between metal objects was a potential ignition source for the scrap metal fire aboard the cargo vessel Tai Yuan in Japan in 2017. Normal vessel motion during the CMT Y Not 6’s ocean transit could have been sufficient to cause the metal cargo to continuously shift and interact in a manner to create a spark between metallic objects. This spark may have ignited known combustible materials contained in the cargo.
Self-heating of metallic materials (metallic borings, shavings, turnings, and cuttings) or nonmetallic materials (such as linseed oil rags, coal dust, hay, wood chips, manure, and latex) is another potential ignition source. The risk increases if the material is stacked or piled and/or the material has been wet and not properly dried.
Although none of these materials were identified following the fire, their potential presence in the scrap metal could not be ruled out. The scrap metal cargo included end-of-life vehicles and appliances. Improperly prepared vehicles and appliances within the scrap metal that could have contained small amounts of flammable liquids or other prohibited materials also could have been an ignition source.
Another potential source of ignition was damaged lithium-ion batteries, although suppliers screened the cargo for prohibited materials such as lithium-ion batteries before it was loaded on board the barge. EMR’s vice president of operations acknowledged the fire dangers associated with lithium-ion batteries, their increasingly prolific use in a wide range of products, and the difficulty in identifying them during the screening process.
A battery-initiated fire was cited as a possible cause in the Tai Yuan casualty report. Combustible materials found within the fire debris suggest numerous potential fuel sources for the fire. Numerous ignition sources were also present: mechanical sparking from shifting metallic cargo, self-heating of metallic or nonmetallic material, improperly prepared vehicles and appliances, and damaged batteries could not be eliminated as ignition sources. Due to the severity of the fire on the barge, which destroyed materials in its area of origin, investigators were not able to determine its exact cause.
The National Transportation Safety Board determines that the probable cause of the fire aboard the deck barge CMT Y Not 6 was the ignition of a combustible material by an undetermined source, such as sparking from shifting metallic cargo, self-heating of metallic or nonmetallic cargo, improperly prepared vehicles and appliances, or damaged lithium-ion batteries.
Monitoring Scrap Cargo: Although scrap metal cargo is typically nonhazardous and poses a low fire risk, there have been recent vessel fires involving such cargo. Even with supplier acceptance agreements and quality assurance personnel visually inspecting scrap metal, metallic and nonmetallic hazardous materials often are present within shoreside scrap metal piles and could be loaded onto vessels. These often-flammable materials elevate the fire risk and can lead to intense fires. Qualified cargo-surveying personnel can assist the vessel’s captain before and during loading operations to limit the presence of hazardous, combustible material in scrap metal. Thermal imagery is an effective tool that could be used to identify hot spots in scrap metal cargo at shoreside facilities. Once scrap metal is loaded onto a barge, it is difficult for a towing vessel crew to visually inspect the cargo while underway.