【1】
Cleaning
Use solvent and emulsion to clean the surface of high-pressure boiler tubes in order to remove the oil, grease, dust, lubricant and similar organics. However, it can not remove the rust, oxide scale, welding flux, etc. from the surface of high pressure
boiler tubes. Therefore, this method can only be seen as an aid for anti-corrosion treatment as well as production.
【2】
Rust Removing by Tools
Use tools like the wire brush to grind the surface of
high pressure boiler tubes, which can remove the loose or peeling oxide scale, rust, welding slag, etc. Rust removing by hand tools can reach the Sa2 level, while rust removing by power tools can reach the Sa3 level. If there is the strong iron scale attaching to the surfaces of high-pressure boiler tubes, the effect of rust removing by tools will not be ideal and the profile depth will not meet the requirements of the anti-corrosive construction.
【3】
Pickling
Generally speaking, there are the chemical and the electrolytic pickling treatments. Due to the corrosion prevention, pipelines only adopt the chemical pickling treatment, which can help to remove the oxide scale, rust and the old coating. Sometimes the chemical pickling treatment can be used as the reprocessing after sand blasting. Chemical cleaning can make the surface reach certain cleanliness and roughness requirements, however, its profiles are shallow and it is easy to result in environmental pollution.
【4】
Rust Removing by Peening (Blasting)
Rust removing by peening (blasting) is that blades rotate rapidly through the drive of high power motors, which makes such abrasive materials as steel grit,steel shot, wire shorts,mineral substance, etc. thrown on the steel tubes' surfaces under the impact of centrifugal force. It can completely remove the rust, oxide and dirt. Besides, the high-pressure boiler tubes can obtain the required uniform roughness with the fierce impact and friction of abrasive materials.
After rust removing by peening(blasting), it can not only enhance the physical absorption capacity of the tube surface but also reinforce the mechanical adhesion between the anti-corrosive coating and the tube surface. Therefore, rust removing by peening (blasting) is the ideal rust removing method for pipeline corrosion control. Generally speaking, shot peening is mainly applied to the internal surface treatment of
high pressure boiler tubes, while shot blasting is mainly used for the external surface treatment of tubes. During the anti-corrosive construction process of pipelines transporting oil (gas), rust removal can extend the service life of the high-pressure boiler tubes.
