This incident refers to a ballast tank explosion of an offshore rig during shipyard repairs. During a repair job in a pre-load tank (ballast tank) on board a rig at a repair yard, an explosion occurred in the tank. The rig was undergoing extensive repairs. During the break time, workers using gas torch inside the pre-load tank, had shut the gas torch valves and left the tank. After the break, when they went in again for continuing their job, there was an explosion in the tank as soon as they ignited the gas torch.
Officer of the Watch 