Corrosion of steel pipes is widespread in various sectors of the national economy and national defense construction, which has brought huge losses to the national economy. It also creates great difficulties for production and life. Whether it is a seamed steel pipe or a seamless steel pipe, under natural conditions (atmosphere, natural water, soil) or human conditions (acid, alkali, salt and other media), corrosion occurs all the time. A spontaneous consumption of unnecessary consumption. The root cause of the steel pipeline is because it is in a thermodynamically unstable state. Under the above conditions, the spiral pipe manufacturer should restore its original relatively stable state. Produce iron oxide carbonate and so on. Or converted to soluble ions. This process is the corrosion process of the metal.
According to statistics, China’s annual output of steel is 160 million tons. Every year, more than 60 million tons are lost due to corrosion. Corrosion is not only a waste of steel resources, but also shortens the service life of pipelines and equipment due to corrosion. The cost of replacing new pipeline equipment far exceeds the price of metal materials itself, and the production cost is increased, which reduces the direct impact of economic benefits. And indirect economic losses are huge. Corrosion products form scale layers, which affect heat transfer and medium flow rate heat transfer efficiency, and energy consumption is greatly increased. Therefore, it is important to do surface treatment of steel pipes.
Use solvents and emulsions to clean the surface of the steel to remove oil, grease, dust, lubricants and similar organic matter, but it can not remove the rust, scale, flux, etc. on the surface of the steel, so it is only used as an aid in the production of antisepsis. means.
Firstly, the surface of the steel is polished with a wire brush and the like, and the loosened or lifted scale, rust, welding slag, etc. can be removed. Hand-opening and rust removal can reach the Sa2 level, and the rust removal of the power can reach the Sa3 level. If the steel surface adheres to the strong iron oxide scale, the rust removal result of the object is not ideal, and the anchor depth required for the anti-corrosion construction cannot be achieved.
Generally, chemical cleaning and electrolysis are used for pickling treatment. Pipeline anti-corrosion is only used for chemical pickling. It can remove oxide scale, rust and old coating, and can sometimes be used as re-disposal after sandblasting and rust removal. Chemical cleaning of course allows the surface to reach a certain degree of cleanliness and roughness, but its anchor pattern is shallow and easily contaminated.
4. Spray (throwing) shot rust removal
Spraying (polishing) rust removal is a high-speed change of high-power motor rotor spray (throwing), so that abrasives such as steel sand, steel shot, wire section and minerals are sprayed (throwing) on the surface of the steel pipe under the action of centrifugal force. Disposal not only completely eliminates rust, oxides and dirt, but also the steel tube can reach the required uniform roughness under the action of abrasive impact and friction. After spraying (polishing) and removing rust, not only can the physical adsorption of the surface of the tube be expanded, but also the mechanical adhesion of the coating to the surface of the tube can be enhanced. Therefore, spray (throwing) and rust removal are the dream rust removal methods for pipeline anti-corrosion. In general, shot blasting (sand) descaling is mainly used for the inner surface of pipes, and shot blasting (sand) descaling is mainly used for surface treatment of pipes.
Spiral submerged arc welded steel pipe for pressure fluid transportation is mainly used for oil and natural gas transportation pipelines. The standard outer diameter wall thickness indicates that there are single-sided welding and double-sided welding. The welded pipe should ensure water pressure test and weld The tensile strength and cold bending function are to comply with the regulations.