Do not weld or cut tanks or vessels which may have contained petrol, oil, spirits, paint or any flammable or explosive substance without making sure that the vessel has been treated to make it safe and that it no longer contains any vapours or trace of the substance.
Before proceeding check the regulations, codes etc., and if in doubt, us. Before beginning to weld or cut a tank or drum:
- Remove residues by thorough boiling or steaming.
- Make certain that the vessel is well vented by removing all plugs and bungs, to release the heated inside air.
- Holes should be drilled in hollow metal parts to prevent the expansion of the air inside causing the vessel to explode.
- Never approach the vessel with a naked light until thorough ventilation, boiling, steaming, or water filling has been carried out.
- Fill the vessel with water to within 25mm to 30mm of the point where the flame is to be applied.
- When water filling of the vessel cannot be carried out, the use of carbon dioxide or nitrogen as a purge while working is recommended.
- Never use oxygen for blowing out, purging or ventilating a vessel.
- Check all joints and seams periodically during the welding or cutting operation for the appearance of oil or grease that may have been lodged there.
- The use of carbon tetrachloride is not recommended for the cleaning of vessels as it gives off a harmful vapour, especially when heated.
- Vessels that have contained oil, petrol, or other flammable liquids must not be used as supports when welding or cutting.
Working from staging
- When working from staging or scaffolding, always have a handrail or rope around the stage.
- Rope off the space below and display a warning notice.
- See that the cylinders are properly secured and out of the way of falling sparks.
Working on coated surfaces
- When flame cleaning, paint burning, cutting or welding on painted or galvanised plate, wear an approved respirator.
- Operators affected by fumes from this work should see a doctor without delay.
Working inside boilers and other confined spaces
- When cutting or welding inside boilers other confined spaces, always keep the gas cylinders outside.
- Special care should be taken to make sure that hoses are in good condition, securely attached to connections and that there are no leaks. Somebody who understands the equipment should be stationed outside to control the gas supply and give the operator any assistance which may be necessary.
- Always light the torch before passing it into the confined space. Bring the torch out whenever work is stopped.
- Have a bucket of water and a fire extinguisher handy. Ventilation may be assisted by
a suction fan. OXYGEN should never be used for the purpose of clearing fumes in a confined space. It can cause fatal accidents through the worker's clothing becoming ignited.