Submerged arc welded steel pipe: It is a spiral seam steel pipe welded by automatic double-wire double-sided submerged arc welding process with strip steel coil as raw material, extruded at regular temperature. The characteristics of submerged arc welded steel pipe: the production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with a larger diameter can be produced with a narrower billet, and welded pipes with different diameters can be produced with the same width billet.
But compared with the straight seam pipe of the same length, the weld length is increased by 30~100%, and the production speed is lower. Therefore, most of the welded pipes with smaller diameters adopt straight seam welding, and most of the welded pipes with large diameters adopt spiral welding.
Submerged arc welded steel pipe material: Q235A, Q235B, 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb. Q345 L245 L290 X42 X46 X70 X80
(1) Raw materials are strip steel coils, welding wires, and fluxes. Before putting into use, they must go through strict physical and chemical tests.
(2) The head-to-tail butt joint of strip steel adopts single-wire or double-wire submerged arc welding, and automatic submerged arc welding is used for repair welding after being rolled into steel pipes.
(3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned, transported and pre-bent.
(4) Electric contact pressure gauges are used to control the pressure of the cylinders 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, misalignment and weld gap are strictly controlled.
(7) Both internal welding and external welding use 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 detector, which ensures 100% non-destructive testing coverage of 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 according to this 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 single steel pipes, the first three steel pipes of each batch must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status of the weld, the surface quality of the steel pipes, and non-destructive testing to ensure the quality of the pipe-making process. Only after passing the test can it be formally put into production.
(11) The part marked by continuous ultrasonic flaw detection on the weld shall undergo manual ultrasonic and X-ray re-examination. If there is a defect, after repair, it shall undergo non-destructive inspection again until it is confirmed that the defect has been eliminated.
(12) The pipes where the strip steel butt welds and the D-joints intersecting with the spiral welds are located have all been inspected by X-ray TV or film.
(13) Each steel pipe has passed the hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe water pressure microcomputer detection device. The test parameters are automatically printed and recorded.
(14) The pipe end is machined to accurately control the verticality of the end face, the bevel angle and the blunt edge.
Submerged arc welded steel pipe and its standard classification: Spiral seam submerged arc welded steel pipe for pressurized fluid transportation (SY5036-83) is mainly used for pipelines for conveying oil and natural gas; spiral seam high frequency welded steel pipe for pressurized fluid transportation (SY5038-83 ), welded by high-frequency lap welding, spiral seam high-frequency welded steel pipes for pressurized fluid transportation. The steel pipe has strong pressure bearing capacity, good plasticity, and is convenient for welding and processing; the spiral seam submerged arc welded steel pipe (SY5037-83) for general low-pressure fluid transportation is made by double-sided automatic submerged arc welding or single-sided welding for water, Submerged arc welded steel pipes for general low-pressure fluid transportation such as gas, air and steam.
Post time: Apr-27-2023