Alert 10 – 07 Tank Welding – High Potential Incident

Alert 10 – 07 Tank Welding – High Potential Incident


The rig accumulator supply tank required maintenance which included the task of welding on the tank and piping. The rig site senior mechanic was walking within the vicinity of the job being performed and noticed the welder welding on the tank. The operation was immediately stopped by the mechanic when he realized the potential explosive atmosphere that existed. The tank itself had not been purged. The tank lid was still closed and secured in place. The contents of the tank had not been emptied nor cleaned prior to the welding taking place. The welder was not aware of the tank contents. There was not a well defined fire watch being utilized. A fire extinguisher or pressurized water hose was not within the working vicinity as required by policy and the Permit to Work procedure. Although a PTW document had been issued, the appropriate personnel were not involved. The document had been incorrectly filled out and many details were not followed as required, including the pre-job safety check off list. The designated fire watch for this maintenance work to be performed had become involved in other duties at the Rig-Site office. A replacement fire watch had not been confirmed either.