The difference between ordinary steel pipe specifications and spiral welded pipes

The difference between ordinary steel pipe specifications and spiral welded pipes

According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency electric resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe and so on. According to the shape of the weld, it can be divided into straight welded pipe and spiral steel pipe. Electric welded steel pipes are used in oil drilling and machinery manufacturing.

Φ219-Φ2032, wall thickness 5-18mm, material Q235, Q345, X42-70 grade.

A spiral welded steel pipe is a steel pipe which is welded and formed by a steel strip or a steel plate to be deformed into a circular shape or a square shape and has a joint on the surface.

According to different welding methods, it can be divided into arc welded pipe, high frequency or low frequency electric resistance welded pipe, gas welded pipe, furnace welded pipe, Bondi pipe and so on.

According to the shape of the weld, it can be divided into a straight welded pipe and a spiral welded pipe.

Electric welded steel pipes are used in oil drilling and machinery manufacturing.

The furnace welded pipe can be used as a water gas pipe, etc., the large diameter straight seam welded pipe is used for high pressure oil and gas transportation, etc.; the spiral welded pipe is used for oil and gas transportation, pipe piles, piers and the like.

Welded steel pipes have lower cost and higher production efficiency than seamless steel pipes.

Straight seam welded pipe has simple production process, high production efficiency, low cost and rapid development.

The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a large diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter by using a blank of the same width.

However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low.

Therefore, most of the smaller diameter welded pipes are straight seam welded. For large diameter welded pipes, spiral welded spiral submerged arc welded steel pipes are used to bend the hot rolled strip into a spiral shape. The inner and outer seams are automatically welded by submerged arc welding. Welding is made into spiral seam steel pipe (also called spiral welded pipe, spiral pipe).

Spiral steel pipe can be widely used in the production of large-diameter steel pipes for the following reasons: 1) Steel pipes of the same width can be used to produce steel pipes of various diameters as long as the forming angle is changed; 2) Steel pipes are formed because of continuous bending The length of the fixed length is not limited; 3) The spiral shape of the weld is evenly distributed on the circumference of the whole steel pipe, so the steel pipe has high dimensional accuracy and high strength; 4) It is easy to change the size, and is suitable for the production of small batch and multi-type steel pipes. .

Steel pipe production process:

The strip head and tail are butt jointed, and the single wire or double wire submerged arc welding is used, and the automatic submerged arc welding is used after the steel pipe is rolled. (3) Before forming, the strip is leveled, trimmed, planed, surface cleaned and pre-bent. (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.

Spiral steel pipe process (high-precision seamless steel pipe, DIN2391 precision seamless steel pipe, cold drawn precision bright pipe): (1) raw materials are steel coil, welding wire, flux.

Strict physical and chemical testing is required before input.

(2) The steel head and tail are butt jointed, and the single wire or double wire submerged arc welding is used, and the automatic submerged arc welding is used after the steel pipe is rolled.

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

(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 molding.

(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 are performed by single-wire or double-wire submerged arc welding by American Lincoln welding machine to obtain stable welding specifications.

(8) The welded seams are all inspected by online continuous ultrasonic automatic injury inspection to ensure the non-destructive testing coverage of 100% spiral welds.

If there is a defect, the alarm is automatically alarmed and sprayed, and the production worker adjusts the process parameters at any time to eliminate defects in time.

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

(10) After cutting into a single steel pipe, the first three inspections of each batch of steel pipe shall be subjected to a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the steel pipe and non-destructive testing to ensure the pipe making process. Once qualified, it can be officially put into production.

(11) The part of the weld with continuous acoustic flaw detection mark, after manual ultrasonic and X-ray review, if it is defective, after repair, it will pass the non-destructive test again until it is confirmed that the defect has been eliminated.

(12) The tube of the butt weld of the strip and the joint of the butt joint intersecting the spiral weld are all inspected by X-ray television or film.

(13) Each steel pipe is subjected to 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.

(14) Pipe end machining, so that the verticality of the end face, the groove angle and the blunt edge are accurately controlled. www.bd-pipefitting.com