There are very few instances where OSHA uses such clear language, but in 1910.252(a) they use the phrase “absolutely certain” and for good reason! This explosion occurred at a wastewater treatment plant in the city of Gumi, South Korea, on October 19, 2016.
1910.252(a)(3)(i) Used containers.
No welding, cutting, or other hot work shall be performed on used drums, barrels, tanks or other containers until they have been cleaned so thoroughly as to make absolutely certain that there are no flammable materials present or any substances such as greases, tars, acids, or other materials which when subjected to heat, might produce flammable or toxic vapors. Any pipe lines or connections to the drum or vessel shall be disconnected or blanked.
This tragic video is the visual demonstration of what happens when we do hot work on a used container/vessel/pipe that was in flammable liquid(s) service without being ABSOLUTELY CERTAIN that there are no flammable materials present.
The Cause:
- The explosion happened while subcontracted workers were performing hot work (welding) on the top of an atmospheric storage tank. The sparks from the welding torch ignited flammable vapors (likely residual chemical vapors or methane gas) inside the tank.
- The blast was powerful enough to blow the heavy metal lid of the tank off completely, as seen in the footage.
This was a double fatality incident. Two (2) workers who were on top of the tank at the time of the explosion were killed instantly by the force of the blast and the subsequent fall.
This footage is frequently used in industrial safety training (often under the title “Double Fatality: Welding on ATM Flammable Storage Tank”) to illustrate the critical importance of gas testing and purging “empty” tanks before beginning any hot work, as atmospheric tanks (ATM) can still contain explosive concentrations of vapor.
Members can download the video from the Video Catalog under Hot Work, Explosion, Unsafe Acts categories.