Procedural breakdown leads to rupture aboard tanker in Texas

The 479-foot Fairchem Filly berthed at the Vopak Terminal on the Houston Ship Channel to offload hexene, a process that required pumping nitrogen into the vessel’s cargo tanks to maintain the chemical’s purity.

- Casey Conley

Two forward cargo tanks overpressurized early in the offloading process and one tank ruptured, releasing hexene into an adjacent ballast water tank, the National Transportation Safety Board (NTSB) said in a report on the May 30, 2019, incident. No one working at the shoreside terminal or on the ship was injured. No pollution was reported.

The ship, registered in the Marshall Islands, required $750,000 in repairs to the No. 3 port cargo tank and the steel deck on top of the tank that was also damaged.

Roughly $100,000 worth of hexene became contaminated.

The NTSB said Fairchem Filly’s crew and Vopak personnel deviated from established practices for cargo discharge, particularly the process of adding nitrogen to “blanket” the hexene. Communication also broke down between ship and shore crews at a pivotal point in the process. As a result, too much nitrogen entered the ship’s No. 3 port and starboard cargo compartments at a rate that exceeded the pressure relief valve’s ability to expel it.

“Since the nitrogen hose connection was improperly configured, the flow rate of nitrogen had to be controlled by the ship or terminal personnel by manually adjusting the dock or ship valve,” the NTSB report said. “Therefore, communication between the ship and terminal personnel was critical.”