1. Features of LSAW steel pipe:

The production process of straight seam submerged arc welded pipes is flexible and can produce any specification and wall thickness within the range. The production efficiency is lower than that of high-frequency straight seam welded steel pipes and spiral welded steel pipes. The biggest advantage of straight seam submerged arc welded pipes is that they can produce specifications and models that cannot be produced by high-frequency steel pipes, spiral steel pipes, and even seamless steel pipes. The production cost of straight seam submerged arc welded pipes is higher than that of high-frequency steel pipes and spiral steel pipes, but there is a lot of room for price discounts compared to seamless steel pipes. Longitudinal submerged arc welded pipes are widely used in heavy steel structure projects, fluid pipeline projects, and foundation piling projects.

2. LSAW Pipe-making process and main equipment:

1) Pre-molding process and main equipment

Steel plate → vacuum crane → ultrasonic testing of steel plate → edge milling → pre-bending.

2) JCO molding process and equipment

J forming→C forming→O forming.

After the steel plate is sent to the hydraulic press for positioning through the conveyor roller, 1/3 of the plate width is formed through the upper and lower molds for the first time, which is called "J forming"; the other 1/3 of the plate width is formed for the second time, which is called "C" Forming"; finally, 1/3 of the plate width is left from the center of the plate to obtain a circular tube shape, which is called "O forming".

3) Post-molding process

Pre-welding (CO₂ shielded welding) → Welding to lead (extinguish) the arc plate → Internal welding → External welding → De-introduction (extinguishing) the arc plate → Slag suction → Full circle → X-ray inspection → Ultrasonic inspection → Front water flushing → Full pipe body Mechanical diameter expansion → post-water flushing → straightening → hydraulic test → ultrasonic testing → pipe end weld grinding → mechanical end trimming → X-ray testing → pipe end X-ray testing → pipe end ultrasonic testing → pipe end magnetic particle testing → weighing Weighing and measuring → finished product inspection → external anti-corrosion → internal anti-corrosion → spray labeling → packaging and storage.