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| Proforma Safety, LLC Proforma PSI…when performance counts. Hydrogen Ignition Incidents Point to Danger When Drilling into Sealed Metal Frames A recent incident at a refinery storage terminal illustrates an unsuspected and serious hazard – hydrogen ignition caused by drilling into sealed frame sections – in this case, a galvanized metal handrail. However, this is not the only instance. Intending to attach a Hazardous Material sign, an employee began to drill a hole in the stairway handrail. As the drill penetrated the pipe wall, gas was released and ignited in a brief but intense burst of flame approximately 500mm long. Both the tops of his hands were burned and his upper right thigh blistered. Upon inspection, it was found that the galvanized metal handrail had a drain/weep hole that was blocked, thus trapping hydrogen in the railing. When oxygen was introduced, the hydrogen ignited. In 1998, The National Institute for Occupational Safety and Health (NIOSH) released a report after investigating ignition incidents resulting from drilling holes into sealed and filled plow frame sections. Two individuals were seriously burned after penetrating sealed sections of their plow frames with electric drills. In both cases, “a roar of escaping gas at high pressure” occurred, throwing the victims back, engulfed in flames. In this case, NIOSH reported that the plow handles were filled with metal punchings for ballast. When the agency sealed the holes and sampled the gases present, it discovered the oxygen from the original air atmosphere was depleted and hydrogen was not only present, but its concentration increased with time under sealed conditions. This occurred in the resealed sections as well.Further testing showed this gas was nearly pure hydrogen at an absolute pressure of 185 psi, or more than 12 times atmospheric pressure. The learning gained from these unfortunate incidents is that drilling or cutting into sealed frame sections on any equipment frame should not be performed, particularly if the frame has been filled. Signs or lights should be attached to the equipment only with built-in or clamped mounting brackets or other nonpenetrating devices. In 2002 BHPSTEEL Australia issued a similarly themed report identifying danger associated with drilling, cutting, or otherwise penetrating sealed metal compartments or frames that have been electrochemically treated, such as zinc in galvanised steel.
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