Occupational Safety and Health Administration OSHA

OSHA Occupational Safety and Health Administration
U.S. Department of Labor

Process: Hot Work


Hazard: Burns and Shocks


A burner working in a confined space noticed that it was five minutes past the start of lunch break. In hurrying to get to the lunch area, he did not completely close the gas valve on his torch. Neither did he take the time to disconnect or shut off the gas supply to the torch at the manifold on deck as he was taught to do in training. The escaping gas mixed with the air in the space until its explosive potential was reached and an electrical spark from equipment in the space ignited the mixture causing an explosion and fire. Fortunately,all the workers had left the area for lunch and no injuries occurred.

Explosion 2
Explosion 1
Explosion 3

Analysis and Preventive Measures

Although the worker’s haste in leaving the area without ensuring that the valves on the torch were tightly shut off contributed to this accident, the fact that the gas supply was not shut off at the manifold as procedure required was the root cause of this accident. It is good practice to shut off the gas at a point outside the confined space when the torch is to be left unattended for a substantial period of time, such as during lunch hour. It is even better practice to remove the torch entirely from the confined space any time the space is unattended to eliminate the hazard. However, 29 CFR 1915.52(a)(4) only requires the torch and hoses be removed from the space entirely when it is left unattended for longer periods, such as overnight. The accident investigation revealed that even though workers were trained to shut the gas supply off at the gas manifold, some supervisors were lax in enforcing this rule. These circumstances clearly had the potential for catastrophic consequences.


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