Welded pipes are divided into general welded pipes, galvanized welded pipes, oxygen-blown welded pipes, wire casings, metric welded pipes, idler pipes, deep well pump pipes, automotive pipes, transformer pipes, electric welded thin-walled pipes, electric welded special-shaped pipes, and scaffold pipes according to their uses. and spiral welded pipes.

General welded pipe: General welded pipe is used to convey low-pressure fluid. Made of Q195A, Q215A, Q235A steel. It can also be manufactured from other mild steels that are easy to weld. Steel pipes are subject to water pressure, bending, flattening and other tests, and have certain requirements for surface quality. Usually, the delivery length is 4-10m, and it is often required to deliver in fixed length (or double length). The specification of the welded pipe is represented by the nominal diameter (mm or inch). The nominal diameter is different from the actual one. The welded pipe has two types of ordinary steel pipe and thickened steel pipe according to the specified wall thickness. The steel pipe is divided into two types: threaded and unthreaded according to the pipe end form.

Carbon Steel Pipes

Galvanized steel pipe: In order to improve the corrosion resistance of steel pipes, general steel pipes (black pipes) are galvanized. There are two types of galvanized steel pipes: hot-dip galvanizing and electro-galvanizing. The hot-dip galvanizing layer is thicker and the cost of electro-galvanizing is low.
Oxygen-blowing welded pipe: used for steelmaking and oxygen-blowing pipe, generally small-diameter welded steel pipes, with eight types of specifications ranging from 3/8 inch to 2 inch. Made of 08, 10, 15, 20 or Q195-Q235 steel strip. In order to prevent corrosion, some are aluminized.

Wire casing: that is, ordinary carbon steel electric-welded steel pipe, used in concrete and various structural power distribution projects, and the commonly used nominal diameter is from 13-76mm. The wall of the wire casing is relatively thin, and it is mostly used after coating or galvanizing, and a cold bending test is required.
Metric welded pipe: the specification is used as a seamless pipe form, and the welded steel pipe represented by the outer diameter * wall thickness in millimeters is welded with ordinary carbon steel, high-quality carbon steel or ordinary low-alloy steel with hot or cold bands, or with hot bands Then it is made by cold drawing method. Metric welded pipes are divided into ordinary energy and thin-walled pipes, which are generally used as structural parts, such as transmission shafts, or conveying fluids, and thin-walled pipes are used to produce furniture, lamps, etc., to ensure the strength and bending test of steel pipes.

Roller tube: used for belt conveyor roller electric welded steel pipe, generally made of Q215, Q235A, B steel and 20 steel, with a diameter of 63.5-219.0mm. There are certain requirements for the bending degree of the pipe, the end surface should be perpendicular to the center line, and the ellipticity, and the water pressure and flattening tests are generally carried out.
Transformer tubes: used to manufacture transformer cooling tubes and other heat exchangers, made of ordinary carbon steel, requiring flattening, flaring, bending, and hydraulic tests. Steel pipes are delivered in fixed length or multiple lengths, and there are certain requirements for the bending degree of steel pipes.
Special-shaped pipes: square pipes, rectangular pipes, hat-shaped pipes, hollow plastic steel doors and windows steel pipes welded by ordinary carbon-bonded structural steel and 16Mn steel strips, mainly used as agricultural machinery components, steel windows and doors, etc.

Welded thin-walled tube: mainly used to make furniture, toys, lamps, etc. In recent years, thin-walled tubes made of stainless steel strips have been widely used in high-end furniture, decoration, fences, etc.
Spiral welded pipe: It is made by rolling low-carbon carbon structural steel or low alloy structural steel strip into a tube blank according to a certain helical angle (called forming angle), and then welding the pipe seam. It can be made with narrower Strip steel produces large diameter steel pipes. Spiral welded pipes are mainly used for oil and natural gas transmission pipelines, and their specifications are expressed by outer diameter * wall thickness. Spiral welded pipes are single-sided welded and double-sided welded. The welded pipes should ensure that the hydraulic test, the tensile strength of the weld and the cold bending performance must meet the regulations.

Classified by production method
(1) According to the process - arc welded pipe, resistance welded pipe (high frequency, low frequency), gas welded pipe, furnace welded pipe.
(2) According to the weld seam - straight seam welded pipe, spiral welded pipe.

Classified by section shape
(1) Simple cross-section steel pipes—round steel pipes, square steel pipes, oval steel pipes, triangular steel pipes, hexagonal steel pipes, rhombus steel pipes, octagonal steel pipes, semicircular steel circles, and others.
(2) Steel pipes with complex cross-sections - unequal hexagonal steel pipes, five-petal plum-shaped steel pipes, double-convex steel pipes, double-concave steel pipes, melon-shaped steel pipes, conical steel pipes, corrugated steel pipes, case steel pipes, and others.

Classified by wall thickness
Thin-walled steel pipes, thick-walled steel pipes.
Classification by end shape
Divided into circular welded pipes and special-shaped (square, flat, etc.) welded pipes.

Category Supplement
1. Ordinary carbon steel wire casing (GB/T3640-88) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings, and installation of machinery and equipment.
2. Straight seam electric welded steel pipe (YB242-63) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. It is usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on.

3. The spiral seam submerged arc welded steel pipe for pressurized fluid transportation (SY5036-83) is made of hot-rolled steel strip coils, spirally formed at constant temperature, welded by double-sided submerged arc welding, and used for pressurized fluid transportation. Spiral seam steel pipe. The steel pipe has strong pressure bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The diameter of the steel pipe is large, the transmission efficiency is high, and the investment in laying pipelines can be saved. It is mainly used for pipelines transporting oil and natural gas.
4. Spiral seam high-frequency welded steel pipe for pressure fluid transportation (SY5038-83) is made of hot-rolled steel strip coils, spirally formed at constant temperature, welded by high-frequency lap welding, and used for pressure fluid transportation Spiral seam high frequency welded steel pipe. The steel pipe has strong pressure bearing capacity, good plasticity, and is convenient for welding and processing; after various strict and scientific inspections and tests, it is safe and reliable to use, the diameter of the steel pipe is large, the transmission efficiency is high, and the investment in laying pipelines can be saved. It is mainly used for laying pipelines for transporting oil and natural gas.

5. Spiral submerged arc welded steel pipes for general low-pressure fluid transportation (SY/T5037-2000) are made of hot-rolled steel coils as tube blanks, spirally formed at normal temperature, and made by double-sided automatic submerged arc welding or single-sided welding. Submerged arc welded steel pipes for general low-pressure fluid transportation such as water, gas, air and steam.
6. Spiral seam high-frequency welded steel pipe for general low-pressure fluid transportation (SY5039-83) is made of hot-rolled steel strip coils, spirally formed at constant temperature, and welded by high-frequency lap welding for general low-pressure fluid transportation. Seam high frequency welded steel pipe.

7. Spiral welded steel pipe for piles (SY5040-83) is made of hot-rolled steel strip coils, spirally formed at normal temperature, and made by double-sided submerged arc welding or high-frequency welding. It is used for civil construction structures, wharves , bridges and other foundation piles.