Production process of spiral tubes

　　 Spiral tube The production process flow:

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

　　(2) For the end-to-end joining of hot-rolled strip steel, either wire drawing or double-wire submerged arc welding is employed; after the strip is rolled into a seamless steel pipe, fully automatic submerged arc welding is used for weld repair.

　　(3) Prior to forming, the hot-rolled strip steel undergoes leveling, edge trimming, edge planing, surface cleaning and conveying, as well as preliminary edge bending.

　　(4) An electrical contact pressure gauge is used to control the pressure of the hydraulic cylinders on both sides of the belt conveyor, ensuring stable conveyance of the hot-rolled strip steel.

　　(5) Select either external-control or internal-control roller forming.

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

　　(7) Both 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, thereby achieving relatively stable welding parameters.

　　(8) All welded joints are inspected online using a continuous ultrasonic automated flaw‑detection system, ensuring widespread adoption of nondestructive testing for spiral welds. If any defects are detected, an audible and visual alarm is triggered and the defect is marked with paint; production personnel can then adjust process parameters on the spot to promptly eliminate the issue.

　　(9) Use gas plasma cutting to cut the seamless steel pipe into individual lengths.

　　(10) After the seamless steel pipe is manufactured as a single piece, each pipe undergoes rigorous full‑inspection procedures, including verification of weld physical properties, chemical composition, fusion quality, surface condition, and nondestructive testing. Only after passing these checks and confirming compliance with the manufacturing process specifications may the pipe be approved for production.

　　(11) At the locations marked on the weld for continuous ultrasonic frequency inspection, manual ultrasonic and X-ray re-inspections are performed. If defects are confirmed, they are repaired and then subjected to nondestructive testing again until it is verified that all defects have been completely eliminated.

　　(12) The butt welds of cold‑rolled strip steel and the T‑joints where they intersect with spiral welds shall all be inspected by X‑ray fluoroscopy or radiography.

　　(13) Each seamless steel pipe undergoes a hydrostatic pressure test, with radial sealing employed for the working pressure. Both the test pressure and duration are rigorously controlled by a microcomputer‑based pressure monitoring system. Key test parameters are automatically printed and recorded.

　　(14) Mechanical machining of pipe ends ensures that the end faces are perpendicular, and that the bevel angles and root faces are precisely controlled.

　　The production process for longitudinal‑seam spiral welded pipes is simple, with high manufacturing efficiency and low costs, enabling rapid market growth. Spiral‑welded pipes generally offer higher strength than straight‑seam steel pipes; they can be produced from narrow billets to yield larger‑diameter welded pipes, or from billets of the same length to manufacture welded pipes of varying diameters. However, compared with straight‑seam steel pipes of the same length, the weld seam length increases by 30% to 100%, and production efficiency is lower. Consequently, smaller‑diameter welded pipes typically use straight‑seam welding, while large‑diameter welded pipes are predominantly manufactured using the spiral‑welding process.