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Spiral steel pipe of the production technology

Views: 0     Author: Site Editor     Publish Time: 2021-06-11      Origin: Site

Spiral steel pipe is a kind of spiral seam steel pipe which is made of strip steel coil as raw material, often formed by warm extrusion and welded by automatic double-wire double-side submerged arc welding process.  The spiral steel pipe will feed the strip steel into the welding pipe unit. After rolling by multiple rolls, the strip steel will gradually roll up to form a circular tube blank with opening gap. The pressure of the extrusion roll will be adjusted to control the weld gap between 1 and 3mm and make both ends of the welding joint flush.  

Production technology and characteristics:spiral steel tube manufacturers - GKSTEELPIPE

(1) raw materials that is, strip coil, welding wire, flux.  They are subjected to strict physical and chemical tests before they are put into use.  

(2) The butt joint of strip steel head and tail adopts single-wire or double-wire submerged arc welding, and automatic submerged arc welding is adopted after rolling into steel pipe.  

(3) before forming, strip steel after leveling, edge cutting, edge planing, surface cleaning and conveying and edge bending treatment.  

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

(5) the use of external control or internal control roller 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 wrong side and the weld gap are strictly controlled.  

(7) Single wire or double wire submerged arc welding is adopted for both internal and external welding by Lincoln welding machine in the United States, so as to obtain stable welding quality.  

(8) The welds after welding are inspected by online continuous ultrasonic automatic flaw tester to ensure 100% nondestructive testing coverage of spiral welds.  If there is any defect, it will automatically alarm and spray mark, so that the production workers can adjust the process parameters at any time and eliminate the defect in time.  

(9) The steel pipe is cut into single pieces by air plasma cutting machine.  

(10) After being cut into a single steel pipe, each batch of steel pipes shall undergo strict first inspection system to check the mechanical properties, chemical composition, dissolution status of the weld, the surface quality of the steel pipe and pass nondestructive inspection to ensure that the pipe making process is qualified before being formally put into production.  

(11) The parts on the weld with continuous acoustic flaw detection marks shall be rechecked by manual ultrasonic and X-ray. If there are any defects, they shall be repaired and then undergo nondestructive inspection again until the defects are confirmed to be eliminated.  

(12) All the tubes where the butt-welding welds of strip steel and the T-joint intersecting the spiral welds are inspected by X-ray TV or film.  

(13) Each steel pipe is subjected to hydrostatic pressure test, and the pressure is radial sealed.  The test pressure and time are strictly controlled by the tube hydraulic microcomputer testing device.  The test parameters are automatically printed and recorded.  

(14) The pipe end is machined so that the verticality of the end face, groove Angle and blunt edge can be accurately controlled.  

Weld process :

1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the weld crystal will not be fused or cracked indirectly.  

2. If the gap is too small, the proximity effect will increase, and the welding heat will be too large, resulting in weld burn loss;  Or after the welding seam is extruded or rolled, deep pits are formed, affecting the surface quality of the welding seam.  

After the two edges of the tube billet are heated to the welding temperature, the common metal grains are formed to penetrate and crystallize each other under the extrusion of the extrusion roller, and finally a firm weld is formed.  If the extrusion pressure of spiral steel pipe is too small, the number of common crystals will be small, and the strength of weld metal will decrease, and cracking will occur after being stressed.  If the extrusion pressure is too large, the molten metal will be extruded from the weld, which will not only reduce the weld strength, but also produce a large number of internal and external burrs, and even cause welding laps and other defects.  

Process characteristics :

Main process characteristics of spiral steel pipe:  

A. In the forming process, the steel plate deformation is uniform, the residual stress is small, and the surface does not produce scratches.  The machined spiral steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, especially in the production of high steel grade thick wall pipe, especially in the aspect of small and medium-sized diameter thick wall pipe, which has incomparable advantages over other technologies, and can meet more requirements of users in the specification of spiral steel pipe.  

B. Adoption of advanced double-sided submerged arc welding technology, welding can be realized in the best position, not easy to appear the wrong side, welding bias and incomplete welding defects, easy to control the welding quality.  

C. Carry out 100% quality inspection on steel pipes, so that the whole process of steel pipe production is under effective detection and monitoring, which effectively guarantees the quality of products.  

D. Whole production  

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