Spiral steel pipes are manufactured from coiled strip steel.

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2016-10-11

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Spiral steel pipe is manufactured from coiled strip steel, formed by cold extrusion under pressure, and welded using an automated double-wire, double-sided submerged-arc welding process.

(1) The raw materials—steel strip coils, welding wire, and flux—are all subjected to rigorous physicochemical testing prior to use.

(2) The steel strip is joined at its ends using single‑wire or double‑wire submerged arc welding, and after coiling into a steel pipe, an automatic submerged arc weld is applied for repair.

(3) Prior to forming, the strip steel undergoes leveling, edge trimming, edge planing, surface cleaning and conveying, and pre‑bending of the edges.

(4) An electrical contact pressure gauge is used to regulate the pressure of the hydraulic cylinders on both sides of the conveyor, ensuring smooth strip steel conveyance.

(5) Employ either external‑control or internal‑control roller forming. Hebei Province spiral steel pipe / spiral steel pipe manufacturer / spiral steel pipe prices

(6) A weld gap control device is employed to ensure that the weld gap meets welding requirements, with strict control over pipe diameter, misalignment, and weld gap.

(7) Both the internal and external welds are performed using Lincoln electric welding machines from the United States, employing either single‑wire or dual‑wire submerged arc welding to ensure stable welding parameters.

(8) All welded seams are inspected using an online, continuous ultrasonic automatic flaw detection system, ensuring 100% nondestructive testing coverage of the spiral welds. If defects are detected, the system triggers an automatic alarm and applies a spray‑on marking; production personnel then adjust process parameters accordingly to promptly eliminate the defects.

(9) Use an air plasma cutter to cut the steel pipes into individual lengths.

(10) After the steel pipes are cut into individual lengths, each batch must undergo a rigorous first‑article inspection, verifying weld mechanical properties, chemical composition, fusion quality, and surface finish. Furthermore, nondestructive testing is performed to ensure that the pipe‑manufacturing process meets specifications before production can commence.

(11) Areas on the weld seam marked by continuous ultrasonic testing shall be re-examined by manual ultrasonic and X-ray inspection. If defects are confirmed, they shall be repaired and then subjected to nondestructive testing again until it is verified that the defects have been eliminated.

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