Spiral steel pipes characteristics: straight seam welded pipe production process is simple, high production efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with larger diameter can be produced with a narrower blank, and the welded pipe with different diameter can also be produced with a blank of the same width. But compared with the straight seam pipe of the same length, the weld length increases by 30~ 100%, and the production speed is lower. Therefore, small diameter welded pipe mostly use straight seam welding, large diameter welded pipe mostly use spiral welding. Spiral pipe and its standard classification: Spiral seam submerged arc welded steel pipe (SY5036-83) for pressure fluid transportation is mainly used for conveying oil and natural gas pipelines; High frequency welded steel tubes with spiral joints for pressure fluid transportation (SY5038-83), welded by high frequency lap welding method for pressure fluid transportation. The steel pipe has strong bearing capacity and good plasticity, which is convenient for welding and processing.
Spiral seam submerged arc welded steel pipe (SY5037-83) for general low pressure fluid transportation is a submerged arc welded steel pipe made by double-sided automatic submerged arc welding or single-side welding method for water, gas, air, steam and other general low pressure fluid transportation. Now the commonly used standards of spiral steel pipes are generally divided into :SY/T5037-2000(ministry standard, also known as spiral seam submerged arc welded steel pipe for ordinary fluid transmission pipeline), GB/T9711.1-1997(national standard, also known as oil and gas industry steel pipe delivery technical conditions Part I: Grade A steel pipe (GB/ T9711.2b steel pipe), API-5L(American Petroleum Institute, also called pipeline steel pipe; It is divided into PSL1 and PSL2), SY/T5040-92 (Spiral seam submerged arc welded steel pipe for pile)
Spiral steel pipes is made of strip coil as raw material, extruded at regular temperature and welded by automatic double wire double submerged arc welding process.
(1) Raw materials, namely strip coil, welding wire, flux. Strict physical and chemical tests should be carried out before investment.
(2) Single or double wire submerged arc welding is used for butt butt of strip steel, and automatic submerged arc welding is used for repair welding after rolling steel pipe.
(3) before forming, strip after leveling, cutting, planing, surface cleaning, transportation and bending processing.
(4) The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth delivery of strip steel.
(5) using 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, staggered edge and weld gap are strictly controlled.
(7) Single wire or double wire submerged arc welding is performed by American Lincoln welding machine for both internal and external welding, so as to obtain stable welding specifications.
(8) All welded welds are inspected by on-line continuous ultrasonic automatic damage tester to ensure 100% nondestructive testing coverage of spiral welds. If there are defects, automatic alarm and spray marking, production workers according to the adjustment of process parameters, timely elimination of defects.
(9) Use air plasma cutting machine to cut the steel pipe into a single root.
(10) After cutting into a single steel pipe, each batch of steel pipe should carry out a strict first inspection system to check the mechanical properties of the weld, chemical composition, melting condition, surface quality of the steel pipe and after nondestructive testing to ensure that the pipe making process is qualified, before it can be formally put into production.
(11) The part with continuous acoustic detection mark on the weld, after manual ultrasonic and X-ray review, if there is a defect, after repair, again through non-destructive testing, until it is confirmed that the defect has been eliminated.
(12) The pipe where the butt weld of strip steel and the t-joint intersecting the spiral weld are all inspected by X-ray TELEVISION or film.
(13) Each steel pipe is hydrostatic tested and the pressure is radial sealed. The test pressure and time are strictly controlled by the microcomputer testing device for water pressure of steel pipe. Automatic printing and recording of test parameters.
(14) The tube end is machined to accurately control the verticality of the end face, groove Angle and blunt edge.
Spiral seam submerged arc welded steel tubes for low pressure fluid pipeline.
1; The scope of
Suitable for water, sewage, air, heating steam and alkenable fluid and other common low pressure fluid pipeline steel pipe, also suitable for other fluid pipeline steel pipe with similar requirements
D — — — — — mm T – steel pipe nominal diameter steel pipe nominal wall thickness mm M – kg/M steel pipe line quality
P – hydrostatic test test the Mpa S – hydrostatic test pressure test, weld residual stress Mpa h mm high
3: size, shape and quality
1 Length of spiral steel tube
(1) The usual length is 6-12m3
(2) Fixed length: within the usual length range, the limit deviation is ±500mm
2 Roundness of spiral steel pipes
Within the length range of pipe end 100mm, the maximum outer diameter of steel pipe shall not be 1% greater than the nominal outer diameter, and the minimum shall not be 1% less than the nominal outer diameter, using calipers, bar gauges or other measuring tools that can measure the maximum and minimum outer diameters.
3; Straightness of spiral steel pipes
(1) The bending degree of the Spiral Steel Pipes shall not exceed 0.2% of the length of the steel pipe. A string or wire can be pulled parallel to the axis of the steel pipe from one end of the side surface of the steel pipe to the other end to measure the maximum distance between the stretched string or wire and the steel pipe surface.
4 End of spiral steel tube
(1) The Spiral Steel Pipes end shall be beveled, the beveling Angle is 30°±50, and the blunt edge size is 1.6±0.8mm. The groove Angle was measured with the vertical line of the steel pipe axis as the reference. No burrs are allowed on the edge of the pipe end.
(2) The end face of the Spiral Steel Pipes should be perpendicular to the axis of the steel pipe, and the limit deviation (cutting Angle) is stipulated as: D < 813mm, cutting Angle ≤1.6mm, D≥813mm, cutting Angle ≤3.0mm