With the continuous development of China's economy and the country's vigorous development of the energy industry, long-distance oil and gas pipelines are an important way to ensure energy. During the anti-corrosion construction of oil and gas pipelines, the treatment method of anti-corrosion steel pipes is the key to determining the anti-corrosion service life of pipelines. One of the factors is that it is the premise of whether the anticorrosion layer and the steel pipe can be firmly combined. Therefore, we should strictly follow the requirements of the anti-corrosion layer specification on the surface of the steel pipe, continue to explore and summarize, and constantly improve the treatment method of the anti-corrosion steel pipe. Nanning Canghai Steel Pipe Co., Ltd. will introduce the anti-corrosion treatment method of anti-corrosion spiral steel pipe for drainage today.

Anti-corrosion process of steel pipe for water

1. Cleaning uses solvents and emulsions to clean the steel surface to remove oil, grease, dust, lubricants and similar organic substances, but it cannot remove rust, scale, welding flux, etc. on the steel surface, so it is only used in anticorrosive production Auxiliary means.

2. Tool derusting mainly uses steel wire brushes and other tools to polish the steel surface, which can remove loose or lifted scale, rust, welding slag, etc.

Handling method of spiral steel pipe anti-corrosion steel pipe can reach Sa2 level, power tool derusting can reach Sa3 level, if the steel surface is firmly adhered to oxide scale, the derusting effect of the tool is not ideal, and the anchoring depth required by the anticorrosion construction cannot be achieved.

3. Pickling is generally done by chemical and electrolytic methods. Pipeline anti-corrosion only uses chemical pickling, which can remove oxide scale, rust and old coating. Sometimes it can be used as reprocessing after sandblasting and rust removal.

Although chemical cleaning can make the surface reach a certain degree of cleanliness and roughness, but its anchor lines are shallow, and it is easy to cause pollution to the environment.

4. Spray (throw) shot rust removal Spray (throw) shot rust removal is driven by a high-power motor to drive the high-speed rotation of the spray (throw) shot blades, so that the abrasives such as steel grit, steel shot, iron wire section, minerals, etc. are subjected to centrifugal force. The surface of the steel pipe is sprayed (blasted), and the anti-corrosion steel pipe treatment method can not only completely remove rust, oxides and dirt, but also achieve the required uniform roughness under the action of abrasive impact and friction. After spraying (throwing) the rust, not only can the physical adsorption of the surface of the pipe be enlarged, but also the mechanical adhesion of the anticorrosion layer to the surface of the pipe can be enhanced. Therefore, the treatment method of spiral steel pipe anti-corrosion steel pipe is an ideal rust removal method for pipeline anti-corrosion.

2. Performance of spiral steel pipe for water

If the gap is too small, the proximity effect will increase, and the welding heat will be too large, resulting in burnt welds; or the welds will form deep pits after extrusion and rolling, which will affect the surface quality of the welds. After the two edges of the tube blank are heated to the welding temperature, under the squeeze of the squeeze roller, the common metal grains form mutual penetration and crystallization, and finally form a strong weld. If the squeezing force is too small, the number of common crystals formed is small, the strength of the weld metal is reduced, and cracks will occur after the force is applied; if the squeezing force is too large, it will be in a molten state.

The spiral steel pipe for water is used to feed the strip steel to the welded pipe unit. After being rolled by multiple rollers, the strip steel is gradually rolled up to form a round tube blank with an open gap. The reduction of the squeeze roller is adjusted to control the weld gap. 1 ~ 3mm, and make both ends of the welding port flush.

If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the joint between the welds will be poor, resulting in unfused or cracked.

If the gap is too small, the proximity effect will increase, and the welding heat will be too large, resulting in burnt welds; or the welds will form deep pits after extrusion and rolling, which will affect the surface quality of the welds.

After the two edges of the tube blank are heated to the welding temperature, under the squeeze of the squeeze roller, the common metal grains interpenetrate and crystallize, and finally a strong weld is formed.

If the squeezing force of the spiral steel pipe is too small, the number of common crystals formed is small, the strength of the weld metal decreases, and cracks will occur after the force is applied; if the squeezing force is too large, the molten metal will be pushed out of the weld, Not only reduces the strength of the weld, but also generates a lot of internal and external burrs, and even causes defects such as welding overlap.