A crew was engaged in cleaning a vessel in a plant. After the lunch break, one of the workers returned early to continue with his cleaning. A co-worker saw him climb the outside scaffold from a distance, but he did not think he entered the vessel. Unfortunately the worker did enter the vessel before the assigned safety guard had returned from his lunch break to approve the re-entry of the cleaning crew. After some time, the crew noticed the worker was missing. A search was initiated. He was discovered lying in a different compartment of the vessel in a pool of sludge. […]