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Differenciating between straight seam and electric resistance welded pipe

Steel pipes are mainly divided into seamless steel pipes and welded steel pipes. There are two kinds of welded steel pipes: one is straight wire welding and the other is spiral welding. Welding method: high frequency welding, arc welding, etc.

High-frequency welded pipes

High-frequency welded pipes are generally straight-slit, but straight-slit welded steel pipes are not necessarily high-frequency welded. The high-frequency straight-slit electric resistance welded steel pipe is formed by the skin effect and the proximity effect of the high-frequency current after the hot-rolled coil plate is formed by the molding machine, and the edge of the tube blank is heated and melted, and pressure welding is performed under the action of the pressing roller to realize the production.

The high-frequency resistance welded steel pipe is different from the ordinary welded pipe welding process. The weld is made of the base material of the steel strip body, and the mechanical strength is better than that of the general welded pipe.

The surface is smooth, high precision, low cost and low weld seam height, which is beneficial to the coating of 3PE anti-corrosion coating. The welding method of high-frequency welded steel pipe and submerged arc welded pipe is significantly different. Since the welding is done instantaneously at high speed, the difficulty in ensuring the welding quality is much higher than that in the submerged arc welding method.

Straight seam steel pipe  

Straight seam steel pipe is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on. 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 larger diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter with 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.

Straight seam steel pipe use, mainly used in water supply engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction. For liquid transportation: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural use: for piling pipes, for bridges; for piers, roads, building structures, etc.


ERW steel pipe is used to transport vapor and liquid objects such as petroleum and gas to meet various requirements of high and low pressure. At present, the world’s transportation pipe field is very important.

1. Welded pipe refers to the general submerged arc welded steel pipe. The electrical engineering uses SC to indicate that the pipe for water and gas is thicker.

2. Line pipe wire and tube is relatively thin with T means that it can be used for threading pipe.

3. ERW tube high-frequency resistance welded steel pipe and ordinary welded pipe welding process welds from the steel strip body base material melting mechanical strength is better than the general welded pipe. ERW means that the resistance welding consumables have high production efficiency, low cost, material saving and easy self-adaptation. They are widely used in important welding processes in various industrial sectors such as aviation, energy, electricity, automobile and light industry.


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