What is straight seam steel pipe?

What is straight seam steel pipe?

Straight seam steel pipe is a general term for high-frequency straight seam, submerged arc straight seam, electric welding straight seam, pipeline straight seam, etc. High-frequency straight seam steel pipe uses the skin effect of high-frequency current to generate high temperature and external force at both ends of the steel plate in a short period of time. Squeeze, which is a true electrodeless base metal butt. Using hot-rolled coils as raw materials, the wall thickness of ERW pipes can be controlled to about ±0.2mm. The ends of the steel pipes adopt the American APL standard or GB/T9711.1 standard. The pipe ends are cut and the conveying length is fixed. In recent years, ERW steel pipes have been widely used as the main steel pipes in urban pipe networks in natural gas pipeline network projects and natural gas enterprises. At present, ERW high-frequency straight seam steel pipes account for 60% of the world's steel pipe usage.

During the anti-corrosion construction process of oil and gas pipelines, the surface treatment of straight seam steel pipes is one of the key factors that determine the anti-corrosion service life of the pipeline. It is the prerequisite for whether the anti-corrosion coating and the steel pipe can be firmly combined. Studies have shown that the service life of the anti-corrosion coating depends on the coating. Layer type, coating quality and construction environment, the impact of surface treatment of straight seam steel pipe on the life of anti-corrosion coating is about 50%. Therefore, steel pipe surface treatment methods should be continuously explored and summarized in strict accordance with the requirements of the steel pipe surface anti-corrosion coating specifications.

1. Cleaning of straight seam steel pipes uses solvents and emulsions to clean the steel surface to remove oil, grease, dust, lubricants and similar organic matter, but it cannot remove oxide scale, rust on the steel surface, flux, etc., and can only be used for anti-corrosion production auxiliary means.
2. If the steel surface is firmly attached to the iron oxide scale, its rust removal effect is not ideal and cannot meet the requirements for anchoring particle depth in anti-corrosion construction. Straight seam steel pipe rust removal tools mainly use tools such as wire brushes to polish the steel surface. Manual rust removal can reach SA2 level, and power tool rust removal can reach SA3 level. It can remove loose or raised oxide scale, rust, and welding slag. wait.
3. Pickling of straight seam steel pipes is generally done by chemical and electrolytic methods, which can be used as a reprocessing after sand blasting and rust removal. Although chemical cleaning can make the surface clean and rough to a certain extent, its anchoring particles are shallow. It is easy to cause pollution to the environment. Pipe anti-corrosion can only be treated with chemical pickling, which can remove oxide scale, rust and old coatings.

Acceptance steps for straight seam steel pipes

1. The approval procedure for batch acceptance of straight seam steel pipes should comply with the corresponding product standards.
2. Straight seam steel pipes should comply with the corresponding product standards including inspection items, sampling quantity, sampling location and test methods. With the consent of the buyer, batch sampling of hot-rolled seamless steel pipes can be carried out according to rolling root rows.
3. If there are items that do not meet the requirements of product standards, the unqualified items should be selected, and double samples should be taken from the same batch of straight seam steel pipes to review the unqualified items. If the re-inspection results do not meet the standards, the batch of straight seam steel pipes shall not leave the factory.
4. Straight seam steel pipes that do not meet the standards (including items whose organization does not meet the standards and are not allowed to be re-inspected) should be submitted to the supplier for acceptance one by one, or a new batch of reheat treatment (reheat treatment no more than twice) should be recommended for acceptance.
5. If there are no special provisions in product standards, the chemical composition of straight seam steel pipes shall be accepted according to the melting composition.

What is the difference between straight seam steel pipe and high frequency straight seam steel pipe?

A welded steel pipe with only one longitudinal weld is a straight seam welded steel pipe. According to the regulations of GB/9711.1, the diameter of straight seam steel pipe is greater than 914.4, the weld angle is 180°, and there can be two straight seams. The welding quality requirements are the same as those of straight seam welded steel pipes.

Straight seam steel pipes can be divided into JCOE straight seam steel pipes and rolled straight seam steel pipes according to the production process.

High-frequency straight seams, submerged arc straight seams, electric welded straight seams, pipe straight seams, etc. are collectively called straight seam steel pipes. High-frequency straight seam steel pipe adopts high-frequency current skin effect, which causes high temperature and short-time external force extrusion at both ends of the steel plate. It is a true electrodeless base metal butt joint. Using hot-rolled coils as raw materials, the wall thickness of ERW high-frequency straight seam steel pipes can be controlled to around ±0. The end of the 2mm steel pipe complies with the American APL standard or GB/T 9711.1 standard. The pipe end is cut and the transportation length is fixed. In recent years, ERW steel pipes have been widely used as the main steel pipes in natural gas pipeline network projects and gas company urban pipeline networks. Currently, ERW high-frequency straight-seam steel pipes account for 60% of the world's steel pipes.

Double-sided submerged arc straight seam steel pipes are also straight seam steel pipes. The submerged arc welded direct welded steel pipe adopts the JCOE cold forming process, the welding seam is made of welding wire, and the granular flux is used for submerged arc. The main production process of submerged arc welded straight seam steel pipe is flexible and can produce any specifications with wall thickness of 325~1420 mm. It meets the international requirements for steel pipe size to a large extent, and high-frequency straight seam steel pipes are usually used in domestic specification production.

High frequency straight seam steel pipe is usually called the original pipe. The name of this industry is different from that of submerged arc welded straight seam steel pipe or thermal expansion high frequency straight seam steel pipe, and their names are often confused.