The difference between ordinary steel pipe specifications and spiral welded pipe
According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe, etc. According to the shape of the weld, it can be divided into straight welded pipe and spiral steel pipe. Welded steel pipes are used in oil drilling and machinery manufacturing.
Φ219-Φ2032, wall thickness 5-18mm, material Q235, Q345, X42-70.
Spiral welded steel pipe refers to a steel pipe with a seam on the surface, which is formed by bending and deforming a steel belt or a steel plate into a circular or square shape.
According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe, etc.
According to the shape of the weld, it can be divided into straight seam welded pipe and spiral welded pipe.
Welded steel pipes are used in oil drilling and machinery manufacturing.
Furnace welded pipes can be used as water gas pipes, etc., large diameter straight seam welded pipes are used for high pressure oil and gas transportation, etc .; spiral welded pipes are used for oil and gas transportation, pipe piles, bridge piers, etc.
Welded steel pipe has lower cost and higher production efficiency than seamless steel pipe.
Straight seam welded pipe production process is simple, high production efficiency, low cost and rapid development.
The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It is possible to use narrow blanks to produce welded pipes with larger diameters. It is also possible to use the same width of blanks to produce welded pipes with different pipe diameters.
But compared with the straight pipe of the same length, the length of the weld is increased by 30-100%, and the production speed is lower.
Therefore, most of the smaller-diameter welded pipes use straight seam welding, and the larger-diameter welded pipes mostly use spiral welding spiral seam submerged arc welded steel pipes to bend the hot-rolled steel strip in a spiral shape. Welded into spiral seam steel pipe (also called spiral welded pipe, spiral pipe).
Spiral steel pipes can be widely used in the production of large-diameter steel pipes for the following reasons: 1) As long as the forming angle is changed, steel pipes of various calibers can be produced with strips of the same width; 2) Because they are continuously bent and formed, the steel pipes The length of the fixed length is not limited; 3) The spiral shape of the weld is evenly distributed on the entire steel pipe circumference, so the dimensional accuracy of the steel pipe is high, and the strength is also high; 4) The size is easy to change, suitable for the production of small batches and many varieties of steel pipes .
Production process of steel pipe:
Strip steel head and tail butt joint, using single wire or double wire submerged arc welding, after coiled into steel pipe, automatic submerged arc welding repair welding. (3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned and transported, and pre-bent. (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 transportation of the steel strip.
Spiral steel pipe process flow (high-precision seamless steel pipe, DIN2391 precision seamless steel pipe, cold-drawn precision bright tube): (1) Raw materials are steel coil, welding wire, flux.
Before input, it must undergo strict physical and chemical tests.
(2) The head and tail of the steel strip are connected by single-wire or double-wire submerged arc welding, and after being rolled into a steel pipe, automatic submerged arc welding is used for repair welding.
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(3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned and transported, and pre-bent.
(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 transportation of the steel strip.
(5) Using 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 all strictly controlled.
(7) Both internal welding and external welding use American Lincoln electric welding machine for single-wire or double-wire submerged arc welding, so as to obtain stable welding specifications.
(8) All welded seams are inspected by online continuous ultrasonic automatic flaw detector to ensure 100% non-destructive testing coverage of spiral welds.
If there are defects, it will automatically alarm and spray marks, and the production workers will adjust the process parameters at any time according to this, and eliminate the defects in time.
(9) Spiral steel pipe is cut into single pieces by air plasma cutting machine.
(10) After cutting into a single steel pipe, each batch of three steel pipe heads must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion state, surface quality of the steel pipe and non-destructive inspection to ensure the pipe making process Only after being qualified can it be officially put into production.
(11) The parts with continuous sonic flaw detection marks on the welding seam are reviewed by manual ultrasound and X-ray. If there are any defects, after repair, they are subjected to non-destructive inspection again until it is confirmed that the defects have been eliminated.
(12) Tubes with butt-welded welds of steel strips and D-type joints intersecting with spiral welds are all inspected by X-ray TV or filming.
(13) Each steel tube undergoes a hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic microcomputer detection device.
(14) The mechanical processing of the pipe end enables the verticality of the end face, the bevel angle and the blunt edge to be accurately controlled.
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