Tool Box Talk: Hot Work Permits

Hot Work Permits

Hot work is defined as “work involving burning, welding, or a similar operation that is capable of initiating fires or explosions.” Hot work also includes other activities with the potential to create a source of ignition such as cutting, brazing, grinding, and soldering.

Workers are potentially at risk not only in the oil and gas industry, where flammables are handled regularly, but also in many other sectors within general industry, such as food production, paper, and wastewater treatment.

The US Chemical Safety Board reported the following accident.

“Three workers were killed in an explosion at a fibreboard manufacturing facility while they were welding on a temporary metal clamp to stabilize a damaged flange connection. The flange was located on top of an 80-foot tall storage tank that contained recycled water and fiber waste. Facility personnel were unaware of the potential presence of flammable gas from the decomposition of the organic material in the tank, and combustible gas monitoring was not typically required or performed prior to starting work.

At the time of the accident, three workers were on a catwalk above the tank; one began welding the flange into place when sparks from the welding ignited flammable vapours inside the tank.

The resulting explosion ripped open the tank lid, knocking two of the workers to the ground 80 feet below. All three workers died of traumatic injuries. A fourth worker, who had been observing the work from a distance, survived with minor injuries.

The CSB analysis of the tank contents determined that anaerobic bacteria had multiplied inside the tank and water recycle system over time, feeding on organic waste material. The bacteria likely produced hydrogen, a highly flammable gas, which ignited during the welding work.

The CSB found that at the time of the incident, PCA supervisors and workers were unaware of the risks of flammable gas production from anaerobic bacteria growth. PCA did not perform a hazard analysis or recognize fibre waste tanks as potentially hazardous. Combustible gas monitoring was not required for the work.”

Key Lessons

1. Use Alternatives – Whenever possible, avoid hot work and consider alternative methods.
2. Analyze the Hazards – Prior to the initiation of hot work, perform a hazard assessment that identifies the scope of the work, potential hazards, and methods of hazard control.
3. Monitor the Atmosphere – Conduct effective gas monitoring in the work area using a properly calibrated combustible gas detector6 prior to and during hot work activities, even in areas where a flammable atmosphere is not anticipated.
4. Test the Area – In work areas where flammable liquids and gases are stored or handled, drain and/or purge all equipment and piping before hot work is conducted. When welding on or in the vicinity of storage tanks and other containers, properly test and if necessary continuously monitor all surrounding tanks or adjacent spaces (not just the tank or container being worked on) for the presence of flammables and eliminate potential sources of flammables.
5. Use Written Permits – Ensure that qualified personnel familiar with the specific site hazards review and authorize all hot work and issue permits specifically identifying the work to be conducted and the required precautions.
6. Train Thoroughly – Train personnel on hot work policies/procedures, proper use and calibration of combustible gas detectors, safety equipment, and job specific hazards and controls.
7. Supervise Contractors – Provide safety supervision for outside contractors conducting hot work. Inform contractors about site-specific hazards including the presence of flammable materials.

“I believe one of the most important priorities is to do whatever we do as well as we can.” Victor Kermit Kiam

Thanks for the share, TO!