The technical requirements for the rust removal works during fabrication of pressure vessels like cryogenic stainless or carbon steel storage tanks, vaporators and oxygen generators are as follows:
1. Rust removal method.
1) For the surface of the outer tank and the pipeline, steel plates shall be sandblasted and derusted first. Then apply the primer to the outer surface of the outer tank, followed with intermediate paint and topcoat.
2) Various exposed steel pipes and ladder platforms are to be derusted with electric grinding wheels.
2. Specific requirements for rust removal.
1) Derusting work should be carried out in the absence of rain and moisture.
2) Before using gas blasting to remove rust, a special sand blasting area should be set up, and proper measures should be taken to prevent the pollution from dust diffusion.
3) Sand blasting and rust removal should use clean, solid and angular emery, quartz sand, siliceous river sand or sea sand with a water content of not more than 1%.
4) The angle of sandblasting should be 30 to 45 degrees with the angle of the steel to prevent pitting.
5) When using an electric grinding wheel to remove rust, there should be reliable electrical protection measures. Operators should wear personal protective equipment (PPE) such as welding helmet, hand shield or goggles for protection against radiation, flying particles or debris, hot slags or sparks etc.
6) Where the rust cannot be removed with an electric grinding wheel, use a manual wire brush or sandpaper.
7) After gas sandblasting or manual rust removal, the metal surface should show a uniform grayish-dark luster and a uniform rough surface. There should be no obvious pits and burrs caused by the original rust or mechanical damage. After rust removal with grinding wheels and emery wheels, the metal surface must not be damaged or deformed.