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| Welding work on starch silo  The technology is from Rembe GmbH - Safety Control. Type of dust is a corn starch. Description of the plant and process: silo (1, see picture) protected by an explosion vent (2), outlet isolated by an explosion-proof rotary valve (3), inlet by a fast acting valve (4); silo installed inside building; pneumatic filling of silo with starch powder. Course of the incident - welding on the silo wall (1) during filling operation resulted in a dust explosion. Consequences: the venting (2) of the explosion into the production building damaged the roof, the welder was seriously injured by falling debris; the silo (1) was not damaged by the explosion as the vents were adequately sized.Causes: the welding work ignited the dust cloud which was present as the plant was being operated: the pressure wave from the uncontrolled venting of the dust explosion into the room severely damaged the roof. Measures: the explosion vents (2) must be ducted to a safe area (ducted to outdoors); a much more state-of-the-art solution is Flameless Venting which allows to relief explosion pressure indoors; welding work at operating plants shall be prohibited; welding (and other hot-work e.g. grinding) in areas where there is a possibility of an explosible atmosphere must be controlled by a 'hot-work' permit system, permit-to-work systems should include special procedures to ensure both that no explosible dust/air mixture can form and that no combustible material can be ignited. write your comments about the article :: © 2009 Construction News :: home page |