Vapor and Gas Freeing a Petroleum Storage Tank
Posted on Tue, Apr 20, 2010 @ 07:43 AM
By Craig Childres, Director of Business Development - Petroleum & Energy
Vapor and gas freeing an above ground petroleum storage tank occurs after the tank has been properly isolated and all product, tank bottoms and residue has been removed from the tank. This can occur by pumping the remaining product and washing the walls, columns, supports and floor to remove any remaining residue. Tank cleaning contractors must establish and implement safe vapor and gas freeing procedures. Acceptable entry conditions must be specified and verified through appropriate testing and monitoring, prior to tank entry.
Procedures should include:
- Vapor and gas freeing (degassing) methods
- Identification and control of ignition sources including bonding and grounding of equipment used in or around the tank
- Elimination and/or control of toxic hazards (vapors, CO, HS, etc.)
- Blower/Vent selection and location to facilitate fresh air being passed/pushed through the storage tank
- Collection, control or dispersal of vapors and gas
- Purging, inerting, flushing, or ventilating the tanks as necessary to eliminate or control atmospheric hazards.
Once a tank has been properly cleaned and vapor/gas free a certification from a independent Marine Chemist can be issued for Safe/Hot Work.