X70 LSAW Pipes

How does a single steel plate become a high-pressure pipe?

The "strong gene" of LSAW tube is hidden in its precise forming and welding process. Huayang steel pipe adopts the international advanced JCOE forming process to gradually "carve" flat steel plate into high-pressure pipe, and the whole process is like a "steel shaping".

Taking DN800 X70 LSAW pipe produced by Huayang for Sinopec's high-pressure gathering and transportation project in 2023 as an example, the process flow is divided into three steps: the first step is pre-bending, and the X70 steel plate with a thickness of 16mm enters a four-roll pre-bending machine, and the equipment accurately presses the edges of both sides of the steel plate into arcs consistent with the curvature of the pipe blank, and the error is controlled within ±0.5mm to avoid stress concentration at the edges during subsequent molding; Step 2: U-O forming, that is, the pre-bent steel plate is sent to a 4000-ton hydraulic press, first pressed into a U shape, and then pressed into an O-shaped tube blank by a special die, and the pressure accuracy of the hydraulic press is stabilized at 0.1MPa to ensure that the roundness deviation of the tube blank does not exceed 1 mm; The third step is welding, which adopts double-wire submerged arc welding technology. The arc covered with flux isolates the air and avoids the oxidation of the weld. The welding wire and the base metal are accurately matched, the welding speed reaches 0.5 m/min, and the tensile strength of the weld is 5% higher than that of the base metal.

After the welding is completed, the pipe will go through a strict "quality inspection checkpoint": the water pressure test will be kept at 1.5 times the working pressure for 30 minutes to ensure no leakage; Ultrasonic and X-ray double flaw detection to realize 100% full coverage detection of weld; Finally, straightness is adjusted by straightener to ensure that each pipe meets the installation requirements. The production director of Huayang Steel Pipe revealed: "The automation rate of our LSAW production line is 90%, and the AI vision inspection system monitors the weld quality in real time, and the defect rate is controlled below 0.2%, far below the industry average of 1.2%."