First, the Acceptance Steps for Straight Seam Steel Pipes
1. The approval procedure for batch acceptance of straight seam steel pipes must comply with the relevant product standards.
2. Straight seam steel pipes must comply with the relevant product standards, including inspection items, sampling quantity, sampling location, and test methods. With the buyer’s consent, hot-rolled seamless steel pipes may be sampled in batches based on the number of pipes rolled.
3. If any items do not meet the requirements of the product standards, the unqualified items should be selected, and duplicate samples should be taken from the same batch of straight seam steel pipes for re-inspection. If the re-inspection results do not meet the standards, the batch of straight seam steel pipes shall not be shipped.
4. Straight seam steel pipes that do not meet the standards (including those with non-compliant microstructure that are not permitted for re-inspection) should be submitted to the supplier for acceptance at one time or undergo reheat treatment in a new batch (reheat treatment should not exceed two times).
5. Unless otherwise specified in the product standard, the chemical composition of the straight seam steel pipe will be accepted based on the melt composition.
Second, what is the difference between straight seam steel pipes and high-frequency straight seam steel pipes? A welded steel pipe with only one longitudinal weld is called a straight-welded steel pipe. According to GB/9711.1, straight-welded steel pipe with a diameter greater than 914.4 mm and a welding angle of 180° can have two identical straight-welded pipes. Straight-welded steel pipe can be divided into JCOE straight-welded steel pipe and rolled straight-welded steel pipe based on the production process. High-frequency straight-welded steel pipe, submerged arc straight-welded steel pipe, electric-welded straight-welded steel pipe, and steel pipe straight-welded steel pipe are collectively referred to as straight-welded steel pipe. High-frequency straight-welded steel pipe utilizes the high-frequency current skinning effect to generate high-temperature, short-term external force extrusion at both ends of the steel plate, creating a true electrodeless metal butt joint. Using hot-rolled coil as raw material, ERW high-frequency straight-welded steel pipe can maintain a wall thickness of approximately ±0. 2mm steel pipe ends comply with the US APL standard or GB/T 9711.1 standard. The pipe ends are cut to a fixed length for transportation. In recent years, ERW steel pipe has been widely used as the main steel pipe for natural gas pipeline projects and gas companies’ urban pipeline networks. Currently, high-frequency straight-welded steel pipe, once left over from wartime explosives, accounts for 60% of the world’s steel pipe supply. Double-sided submerged arc straight seam steel pipe is also a straight seam steel pipe. Submerged arc welded straight seam steel pipe utilizes the JCOE cold forming process, with welding wire and a submerged arc flux. The production process is flexible and can produce any size, with wall thicknesses ranging from 325 to 1420 mm. It largely meets international requirements for steel pipe dimensions, while high-frequency straight seam steel pipe is typically used for domestic standard production.
High-frequency straight seam steel pipe is often referred to as raw steel pipe. This industry name is different from submerged arc welded straight seam steel pipe or thermal expansion high-frequency straight seam steel pipe, and the two names are often confused.
Post time: Sep-16-2025