What are the details of the correct operation and acceptance methods for straight seam steel pipes

Currently, there are increasingly more types of straight seam steel pipes. With the rapid development of strip steel continuous rolling production and the advancement of welding and inspection technologies, weld quality is constantly improving, and the variety and specifications of welded steel pipes are increasing daily. The specifications of hot-rolled round steel are 5.5-250 mm. Among them: small round steel of 5.5-25 mm is mostly supplied in straight bundles and is commonly used as reinforcing bars, bolts, and various mechanical parts; round steel larger than 25 mm is mainly used for manufacturing mechanical parts or as seamless steel pipe blanks.

First, what are the correct operating procedures for straight seam steel pipes?

1. When hoisting straight seam steel pipes, the wire rope must not be pulled at an angle to prevent it from derailing.

2. During operation, pay attention to ensuring the safety of personnel and equipment.

3. Regularly check the switches at the front and rear of the trolley, and ensure that the switch at the maximum lifting limit of the hook is working properly and sensitively.

4. Lubricate the gears, sprockets, chains, ropes, and other lubrication points of the straight seam steel pipes on schedule.

5. Operators of the jib crane must closely coordinate with the hoisting personnel and follow the hoisting instructions.

6. The hook must be fully loaded with the steel coil.

7. Replace the wire rope when 10% of its strands are broken.

8. Regularly check the hook's lifting brake for proper function and sensitivity.

9. When hoisting steel coils of straight seam steel pipes, lift and lower them gently; the operation must be steady, accurate, and light.

Second, what are the welding techniques for straight seam steel pipes?

1. Verify the specifications of the welding wire and flux according to the welding process specifications to prevent welding accidents caused by using the wrong welding wire and flux.

2. Monitor the welding environment. When the welding environment is unfavorable (temperature below 0℃, relative humidity above 90%), take appropriate measures before welding.

3. Before pre-welding, check the bevel dimensions, including gap, blunt edge, angle, and misalignment, to ensure they meet the process requirements.

4. Ensure the selected welding current, welding voltage, welding speed, and other process parameters are correct during submerged arc automatic internal and external welding.

5. Supervise welders to fully utilize the length of the arc-starting plate at the pipe end during submerged arc automatic welding, enhancing the efficiency of the arc-starting plate during internal and external welding. This helps improve pipe end welding efficiency.

6. Supervise welders to ensure that slag is thoroughly cleaned before repair welding, that joints are properly treated, and that there is no oil, rust, slag, water, paint, or other contaminants at the bevel.

Third, what are the acceptance methods for straight seam steel pipes?

1. The inspection and acceptance of straight seam steel pipes should be conducted by the supplier's technical supervision department.

2. The supplier guarantees that the delivered straight seam steel pipes conform to the relevant product standards. The buyer has the right to inspect and accept them according to the relevant product standards.

3. Straight seam steel pipes should be submitted for acceptance in batches, and the batching rules should conform to the relevant product standards.

4. The inspection items, sampling quantity, sampling location, and test methods for straight seam steel pipes shall be in accordance with the relevant product standards.

5. If any test result of the straight seam steel pipe fails to meet the product standard requirements, the non-conforming pipes should be removed, and twice the number of samples should be randomly selected from the same batch of straight seam steel pipes for retesting of the non-conforming item.

ERW high-frequency straight seam steel pipes, made from hot-rolled coils, offer advantages such as uniform wall thickness controllable to approximately ±0.2mm, end beveling according to APL or GB/T9711.1 standards, and delivery in fixed lengths. In recent years, ERW steel pipes have been widely adopted as the main steel pipe for urban pipeline networks in various gas pipeline projects and gas companies. Currently, ERW high-frequency straight seam steel pipes account for 60% of the world's steel pipe usage. Straight seam steel pipes refer to welded steel pipes with a single longitudinal weld seam. GB/9711.1 stipulates that straight seam steel pipes with a diameter greater than 914.4 mm can have two straight weld seams, with an included angle of 180 degrees. The technical parameters of the straight seam steel pipe with the same weld seam must be consistent.

According to the manufacturing process, straight seam steel pipes are classified into: ERW high-frequency straight seam steel pipes, JCOE straight seam steel pipes, and rolled straight seam steel pipes. Straight seam steel pipes are a general term for products manufactured using processes such as high-frequency straight seam, submerged arc straight seam, electric welded straight seam, and pipeline straight seam. High-frequency straight seam steel pipes utilize the skin effect of high-frequency current to generate high temperatures at both ends of the steel plate in a short time, and then forcefully fuse them, resulting in a true electrodeless butt welding process. In Hebei, straight seam steel pipes often refer to JCOE double-sided submerged arc straight seam steel pipes, which employ the JCOE cold forming process. The weld seam uses welding wire and simultaneously uses granular flux for submersion, hence the name submerged arc straight seam steel pipe.