Wednesday, 21 November 2012 00:12

Welding on Hollow Structures (Part 2)

Many metal fabrication shops and welders perform repair or modification work on old equipment, both in a shop setting and in the field. Performing repair work on hollow structures can pose a significant hazard other than a large internal pressure buildup from heating which we discussed in the last welding safety article.

As an easy introduction, consider the need to perform cutting or welding on a tank that used to contain a flammable solvent. Empty of liquid means it is safe, right? Not necessarily. It is the vapors that burn, not the liquid. An “empty” hollow structure such as a tank could be the worst case scenario, full of flammable vapors. Given the right ratio of vapor to oxygen, that hollow structure is like a bomb, ready to explode as soon as enough energy is transferred from the hotwork process.

Published in Guest Columns