Close Call On Rig – Explosion Danger When Welding Tank

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April 23, 2010


An alert rig site senior mechanic spotted a welder carrying out a job that could have led to an explosion. It is a reminder to check thoroughly what’s inside a tank before welding the outside.

A safety alert from the International Association of Drlling Contractors says: “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.

ï‚· Lack of pre-job planning and hazard assessment (JSA) not implemented or carried out.
ï‚· Personnel directly involved in the task failed to recognize the hazard potential.
ï‚· Inadequate safety leadership and poor job planning by rig site management.
ï‚· Incorrect implementation of the Permit to Work (PTW) system. All aspects of this document had not
been followed or utilized.

To address this incident, this company did the following:
ï‚· Training for all rig site personnel on the understanding and utilization of the PTW system.
ï‚· Training for employees directly involved in future and potential fire-watch duties.
ï‚· Verifying the qualifications of all on-site rig welders and their understanding of maintenance and work
procedures involving pressure vessels and flammable liquids or gases and the potential for explosion.
ï‚· Pre-job check by the Senior Rig Site Manager prior to and following the signing of the Permit to Work  System.
ï‚· Senior rig site personnel to communicate the responsibilities of employees to perform duties such as firewatch
or confined-space entry monitoring and compliance.

Download the Safety Alert Here


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