Welded Steel Pipe Specifications, Classification And Various Uses

Steel pipe is a kind of hollow long steel, a large number of pipelines used to transport fluids, such as oil, natural gas, water, gas, steam, etc. In addition, in the same bending and torsion strength, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. Also commonly used for the production of various conventional weapons, gun barrels, shells, etc.. And welded steel pipe, also known as welded pipe, belongs to the seamless steel pipe, is made of steel plate or strip steel after coil forming and then welding, usually 6 meters in fixed size. Welded steel pipe production process is simple, high production efficiency, more varieties and specifications, less investment in equipment, but the general strength is lower than seamless steel pipe.

Welded steel pipe classification

Classification by production method

(1) According to the process - arc welding pipe, resistance welding pipe (high frequency, low frequency), gas welding pipe, furnace welding pipe

(2) According to the weld seam - straight seam welded pipe, spiral welded pipe

Classification by cross-section shape

(1) simple cross-section of steel pipe - round steel pipe, square steel pipe, oval steel pipe, triangular steel pipe, hexagonal steel pipe, rhombus steel pipe, octagonal steel pipe, semi-circular steel round, other

(2) complex cross-section of steel pipe - unequal hexagonal steel pipe, five plum-shaped steel pipe, double convex steel pipe, double concave steel pipe, melon shaped steel pipe, conical steel pipe, corrugated steel pipe, case steel pipe, other

According to the wall thickness can be divided into: thin-walled steel pipe and thick-walled steel pipe

According to the shape of the end can be divided into: round welded pipe and shaped (square, flat, etc.) welded pipe;

Classified by use

General welded pipe, galvanized welded pipe, oxygen blowing welded pipe, wire casing pipe, metric welded pipe, roller pipe, deep well pump pipe, automobile pipe, transformer pipe, electric welded thin-walled pipe, electric welded shaped pipe, scaffolding pipe and spiral welded pipe.

Main Applications

Widely used in waterworks, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction, is one of the twenty key products developed in China.

For liquid transportation: water supply, drainage. For gas transportation: gas, steam, liquefied petroleum gas.

Welded steel pipe specifications

Welded steel pipe is divided into galvanized and un-galvanized according to the form of surface treatment of the pipe. Welded steel pipe can be divided into two kinds when it leaves the factory: one is with threads on the end of the pipe, and the other is without threads on the end of the pipe. Welded steel pipe with threaded pipe ends, each pipe length of 4 to 9m, without threaded welded steel pipe, each pipe length of 4 to 12m.

Welded steel pipe is divided into thin-walled steel pipe, thickened steel pipe and ordinary steel pipe according to the thickness of the pipe wall. The most used on the process pipeline is ordinary steel pipe, its test pressure is 2.0MPa. thickened steel pipe test pressure is 3.0MPa.

Welded steel pipe connection method is more, there are threaded connection, flange connection and welding. Flange connection is divided into threaded flange connection and welding flange connection, welding method is divided into gas welding and arc welding.

Commonly used welded steel pipe specifications range: for the nominal diameter of 6 ~ 150mm

Welded steel pipe according to the molding process can be broadly divided into three categories:

First, resistance welding steel pipe

Resistance welding steel pipe, English name ERW (Electric resistance welded Pipe), the type of weld is straight seam. Resistance welding is used without filler metal pressure welding method, the weld is not filled with other components, relying on the high-frequency current skin effect and proximity effect, so that the edge of the plate is instantly heated to the welding temperature, by the extrusion rollers extrusion to form a forging organization of the weld.

Resistance welding steel pipe can be divided into two categories: high frequency resistance welding HFW (High frequency welded pipe) and low frequency resistance welding LFW (Low frequency welding).

ERW steel pipe is mainly used for the transmission of oil, natural gas and other vapor-liquid objects, can meet the high and low-pressure requirements, the world's transmission pipe in the field of pivotal position.

Spiral Welded Steel Pipe

Spiral welded steel pipe, English name SSAW (Spiral submerged-arc welding pipe), the type of weld seam is spiral seam. The method of submerged arc welding, internal and external double-layer welding. Submerged arc welding (including submerged arc surfacing and electroslag surfacing, etc.) is an important welding method, with its inherent advantages of stable weld quality, high welding productivity, no arc light and very little fume.

Spiral welded pipe manufacturing larger caliber, able to reach more than 3000mm, more suitable for large-caliber pipeline transportation and building structures.

Third, straight seam welded steel pipe

LSAW steel pipe, English name LSAW (Longitudinally Submerged Arc Welded Pipe), the type of weld is straight seam. The same method of submerged arc welding, inside and outside the double-layer welding. LSAW steel pipe manufacturing wall thickness is larger, the use and spiral welded steel pipe is similar.

LSAW steel pipe according to the different molding process, can be divided into two categories: UOE (Uing and Oing forming pipe) and JCOE (J-ing, C-ing and O-ing pipe). UOE molding method (U-forming, O-forming, E-expansion), JCOE molding method (steel plate pressed into the J-type, and then pressed into the C-type and O-type, and after the Expansion).

It is necessary to specify that the submerged arc welding process (SAW) belongs to the electric fusion welding (EFW Electric Fusion Welded Pipe), that is, through one or several self-consuming electrodes and workpieces between the metal heating to make the combination of metal to metal, a process, the arc so that the metal and filler material fully melted, without pressure, filler metal part of the diligence of the whole from the electrode The filler metal part of the hard work all comes from the electrode.