Spiral steel pipe manufacturing process

Spiral steel pipe (SSAW/ SAWH) is also called spiral welded pipe. It is made by rolling a low-carbon structural steel or low-alloy structural steel strip at a certain helical angle (called a forming angle) into a tube blank, and then welding the tube seams. It can be produced with narrower strip steel. Large diameter steel pipe.

The manufacturing process of the spiral steel tube (SSAW):

(1) The raw materials are strip coil, welding wire and flux. They must undergo strict physical and chemical inspections before being put into use.

(2) The head and tail of the strip are butted by single wire or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after rolling into a steel pipe.

(3) Before forming, the strip is leveled, trimmed, planed, surface cleaned and conveyed and pre-bending.

(4) The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth conveying of the strip.

(5) Adopt external control or internal control roll forming.

(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are strictly controlled.

(7) Both internal welding and external welding use the American Lincoln welding machine for single wire or double wire submerged arc welding, so as to obtain stable welding specifications.

(8) The welded seams are all inspected by an online continuous ultrasonic automatic flaw tester, which ensures 100% non-destructive testing coverage of the spiral welds. If there is a defect, it will automatically alarm and spray the mark, and the production workers can adjust the process parameters at any time accordingly to eliminate the defect in time.

(9) Use an air plasma cutting machine to cut the steel pipe into single pieces.

(10) After cutting into a single steel pipe, each batch of steel pipes must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion condition of the weld, the surface quality of the steel pipe and non-destructive testing to ensure that the pipe making process is qualified. Only then can it be officially put into production.

(11) The parts with continuous sonic flaw detection marks on the welds shall be re-examined by manual ultrasonic wave and X-ray. If they are indeed defective, they shall be repaired and subjected to non-destructive inspection again until it is confirmed that the defects have been eliminated.

(12) The tube where the strip butt welding seam and the T-joint intersecting with the spiral welding seam are located shall all be inspected by X-ray television or filming.

(13) Each steel pipe is tested by hydrostatic pressure, and the pressure is radially sealed. The test pressure and time are strictly controlled by the water pressure microcomputer detection device of the steel pipe. The test parameters are automatically printed and recorded.

(14) The pipe end is machined so that the verticality of the end face, the bevel angle and the blunt edge are accurately controlled.

The main process characteristics of spiral steel pipe

a. During the forming process, the steel plate is uniformly deformed, the residual stress is small, and the surface is not scratched. The processed spiral steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, especially in the production of high-grade thick-walled pipe, especially small and medium-diameter thick-walled pipe, which has incomparable advantages in other processes, which can meet more requirements of users in the specification of spiral steel pipe.
b. Using the process of double-sided submerged arc welding, welding can be realized in position, and defects such as wrong edge, welding deviation and lack of penetration are not easy to occur, and it is easy to control the welding quality.
c. 100% quality inspection of steel pipe, so that the whole process of steel pipe production is under effective detection and monitoring, effectively ensuring product quality.
d. All the equipment of the whole production line has the function of networking with the computer data acquisition system to realize the real-time transmission of data, and the technical parameters in the production process are controlled by the central control room.