Type of dust
Corn starch

Description of the plant and process
• Silo (1) 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.

You learn more comprehensive knowledge of industrial explosion protection in the latest BOSS (REMBE®’s Booklet of Safety and Security).