Cleaning method of large-diameter steel pipe:
1. Spray blasting and de-rusting: the high-power motor drives the blades to rotate at high speed, so that steel sand, steel shot, iron wire segment, minerals, and other abrasives are sprayed and projected on the surface of the steel pipe under the action of centrifugal force. On the one hand, rust, oxides, and Dirt, on the other hand, under the violent impact and friction of abrasives, the steel pipe reaches the required uniform roughness.
2. Cleaning: Solvents and emulsions are usually used to clean the surface of large-diameter steel pipes for grease, dust, lubricants, and organic matter. However, for the rust, scale, and welding slag on the surface of the steel pipe that cannot be removed, other treatment methods are needed.
3. Pickling: common pickling includes chemical and electrolytic methods. However, only chemical pickling is used for the anti-corrosion of pipelines. Chemical pickling can achieve the cleanliness and roughness of the surface of large-diameter steel pipes, which is convenient for subsequent anchor lines. Usually, as a reprocessing after shot peening (sand).
4. Derusting tools: large-diameter steel pipe surface scale, rust, and welding slag can be cleaned and polished with a wire brush. There are two types of de-rusting tools: manual and power. The de-rusting of manual tools can reach the Sa2 level, and the de-rusting of power tools can reach the Sa3 level. If there is a particularly strong scale attached to the surface of the steel pipe, it may not be cleaned with the help of tools, so other methods need to be found.
Connection method of large diameter steel pipe:
1. Large-diameter steel pipe heat-shrinkable fittings: When connecting pipes, on-site welding can be used. Welding points cannot be handled at the construction site, and heat-shrinkable pipe fittings are used as supplementary seals, which shrink under the action of heat to achieve shrinkable seals.
2. Large-diameter steel pipe quick-connect flange type: ring-shaped argon-arc welding is performed on the flange and the matching, and the gasket between the flanges is compressed with a quick clamp, which acts as a seal to complete the matching connection.
3. Large-diameter steel pipe limit compression type: the piping adopts a flanging or port welding ring, and the connection method is a union or semi-union connection. After compressing the limit seal of the rubber sealing ring by 20%-30%, it enters the metal sealing groove. A limit seal is used to protect the sealing element. It can be used in harsh environments such as foundation subsidence, high temperature, and high pressure.
4. Welding type of large-diameter steel pipe: circular argon arc welding is performed on the usual socket-type pipe fittings and matching, which acts as a seal and completes the matching connection.
5. Large-diameter steel pipe tapered thread type: the outer threaded sleeve and the matching are ring-shaped argon arc welding, and the inner threaded pipe fittings are connected by a tapered thread to seal and complete the matching connection. It can be used in harsh environments such as foundation subsidence, high temperature, and high pressure.
6. Compression type of large-diameter steel pipe: insert the pipe into the pipe fitting, and the two ends of the pipe fitting are protruding U-shaped grooves, and the built-in sealing ring is connected by pressing the socket part of the special pipe fitting tool.
7. Compression type: Insert the pipe into the nozzle of the pipe fitting, fasten it with a nut, and compress the casing at the nozzle part through the sealing ring with the screw force, which acts as a seal and completes the pipe connection.
Methods of improving the rust resistance of large-diameter steel pipes:
1. When sandblasting or manual mechanical de-rusting is used, due to the peeling of the oxide scale on the large-diameter steel pipe, the metal on the surface of the large-diameter steel pipe is directly exposed in the air. If a primer is not applied in time, the surface of the large-diameter steel pipe is easy to resurface. Rust affects the adhesion of the paint film. Since paint is a time-sensitive material, the backlog of inventory is easy to expire, so the main indicators of the paint should be re-inspected before use, and the results can only be used if they meet the standards.
2. Rust removal: This is an important process before the coating of large-diameter steel pipes and components, and is the key to large-diameter steel pipes. Rust removal can improve the adhesion of anti-rust paint, thereby prolonging the service life of large-diameter steel pipes.
3. After sandblasting shot blasting, or pickling process, the surface of large-diameter steel pipes will be relatively clean, such as iron oxide scale and rust, which improves the adhesion of the coating. When the installation site is unconditionally treated by sandblasting or shot blasting, manual mechanical rust removal can be used, but the rust removal level can be achieved.
Post time: Mar-10-2023