aldocigna
Mechanical
- Aug 28, 2006
- 24
In regenerating H2SO4 plants it's often necessary to weld some patchs on pipe or equipment (carbon steel type) with liquid acid inside to eliminate leakages or add corrosed thickness.
Often it's very difficult to clean very well the metal surface before welding.
This is a very dangerous practice because it's possible to create acid scomposition and hydrogen presence
For this reason many hot tape procedure (API RP2201)say unusable welding in service in this condition
What safety welding procedure do you suggest to avoid this danger? perhaps nitrogen protection?
Is this risk relative to equipment with acid inside under liquid level only or relative to equipment with acid gas inside where it's possibile the presence of a little quantity of acid condensate near the leakage point too?
Is the risk relative to acid scomposition only or relative to Hydrogen brittle fracture too (nelson curves)?
Tanks
Aldo Cigna
Often it's very difficult to clean very well the metal surface before welding.
This is a very dangerous practice because it's possible to create acid scomposition and hydrogen presence
For this reason many hot tape procedure (API RP2201)say unusable welding in service in this condition
What safety welding procedure do you suggest to avoid this danger? perhaps nitrogen protection?
Is this risk relative to equipment with acid inside under liquid level only or relative to equipment with acid gas inside where it's possibile the presence of a little quantity of acid condensate near the leakage point too?
Is the risk relative to acid scomposition only or relative to Hydrogen brittle fracture too (nelson curves)?
Tanks
Aldo Cigna
