The National Transportation Safety Board (NTSB) has released an investigation report into the blaze on the bridge of the crude tanker S-Trust 12 months ago, to provide lessons learned.
The incident
On November 13, 2022, about 1530 local time, a fire started on the bridge of the oil tanker S-Trust while the vessel was docked at the Genesis Port Allen Terminal in Baton Rouge, Louisiana. Fire teams from the vessel’s crew extinguished the fire about 1550. There were no injuries, and no pollution was reported. The damage to the vessel was estimated at $3 million.
The S-Trust was a Liberian-flagged, 800-foot-long, steel-hulled liquid bulk cargo vessel (oil tanker) owned by New Trend Ltd and operated by Stalwart Management Ltd. The vessel was built in 2005 and had a cargo capacity of 741,732 barrels. The vessel’s superstructure contained living quarters, the galley, a
ship’s office, the cargo control room, and the bridge; it consisted of five decks: the main deck, A deck, B deck, C deck, and the bridge deck.
Investigators found the remains of three batteries (one nickel-metal hydride and two lithium-ion) on the communications table. The single nickel-metal hydride battery (all of its six cells) was intact; one of the lithium-ion batteries (both cells) was found intact in the remains of the chargers (one nickel-metal hydride charger and one lithium-ion charger). Investigators only found components of the second lithium-ion battery (a two-cell battery). Lithium-ion battery cell explosions are typically caused by a thermal runaway; as such, the initial orange flash and puff of smoke on the video feed was likely the result of one of the missing lithium-ion cells exploding due to a thermal runaway. The heat produced from a thermal runaway of a lithium-ion battery cell can exceed 1,100° F, which can easily cause any nearby combustible material to ignite, including adjoining cells of the same battery. As the fire expanded, the closed-circuit video captured a second flash, followed by a flaming object being propelled from the fire and landing on the deck of the bridge, where it continued to burn. This was most likely the other missing lithium-ion cell from the same battery. Based on the video, investigators determined that the second missing lithium-ion cell also experienced a thermal runaway, most likely initiated from the heat of the fire started by the initial battery cell thermal runaway.
A thermal runaway occurs when a cell overheats and combusts; it is a chemical reaction that can occur to any type of battery cell if it is damaged, shorted, overheated, defective, or overcharged. It is possible, based on the battery remains’ location among the charger remains, that one of the batteries had been left in the charger, which could have led to overcharging. However, a crewmember told investigators that the batteries were not in the chargers before the fire. Further, investigators were not able to find the missing cells, and, due to the explosion, the extensive heat from the thermal runaway reaction, and subsequent fire on the bridge, the battery cells may have been completely consumed. Therefore, investigators could not examine the first cell that exploded to determine the exact cause of the initial thermal runaway.
Once the vessel was docked at the terminal and cargo operations began, the bridge watch ended, so no one was stationed on the bridge at the time the fire started. The first indication crewmembers had of a possible fire aboard was the loss of the closed-circuit camera feed to the monitor in the master’s office. Had the fire occurred while the vessel was underway, there would have been personnel on the bridge, and the fire would have been immediately detected. Additionally, the vessel’s bridge did not have a smoke or fire detection system (nor was it required to), which also allowed the fire to grow undetected.
Probable Cause
The National Transportation Safety Board determines that the probable cause of the fire on the bridge of the S-Trust was the thermal runaway of one of the cells in a lithium-ion battery for a UHF handheld radio.
Lessons Learned
Lithium-Ion Battery Fires
A lithium-ion battery cell, if damaged, shorted, overheated, defective, or overcharged, can spontaneously experience a thermal runaway, a chemical reaction that can cause the cell to ignite and explode. A cell that has exploded can be propelled from its initial position within a battery. Due to the potential for rapid expansion of a lithium-ion battery fire, detection, containment, and extinguishment are essential to prevent damage to a vessel.
Crews can help prevent thermal runaways and ensuing fires by doing the following:
- follow manufacturers’ instructions for the care and maintenance of lithium-ion batteries,
- properly dispose of damaged batteries,
- avoid unsupervised charging, and
- keep batteries and chargers away from heat sources and flammable materials.
Additionally, companies should ensure that lithium-ion batteries and devices that use lithium-ion batteries are certified by Underwriters Laboratory or another recognized organization. Should a lithium-ion battery fire occur, crews can attempt to extinguish the fire with water, foam, CO2, or other dry chemical or powdered agents. However, if the battery fire cannot be extinguished, personnel should attempt to allow the pack to burn in a controlled manner; this includes watching for nearby cells that may also experience thermal runaway and extinguishing other combustibles that may catch on fire.
