Advantages of ERW steel pipe

"ERW pipe" is Electric Resistance Welding, abbreviated as ERW. It is used to transport vapor and liquid objects such as oil and natural gas. It can meet various requirements of high and low pressure and occupies a decisive position in the field of transportation pipes in the world.

First, ERW steel pipes have good quality and long service life; second, ERW steel pipes have good surface quality, uniform coating, save a lot of coating materials, and low anti-corrosion costs for steel pipes; third, ERW steel pipes have high geometric and dimensional accuracy, fast butt welding speed, and on-site construction high efficiency, in addition to reducing the cost of spinning.

ERW steel pipe vs. SSAW steel pipe

Due to the different shaping, welding and processes in the pipe making process of ERW steel pipes and SSAW steel pipe, there are certain differences in the performance of the two steel pipes.

(1) The surface quality of ERW steel pipes is better than SSAW steel pipe. The surface of ERW steel pipes is smooth, flat and beautiful. SSAW steel pipes have internal and external weld reinforcements.

(2) The weld seam of ERW steel pipe is shorter than SSAW steel pipe. The weld seam of ERW steel pipe is as long as the length of the steel pipe, while the weld length of SSAW steel pipe is generally 1.4-1.7 times the length of the steel pipe. The longer the weld, the higher the chance of welding defects.

(3) The geometric requirements for ERW steel pipes and SSAW steel pipes in the standard are basically the same. However, in terms of physical objects, ERW steel pipes have sizing and straightening processes. Therefore, the geometric dimensions are more accurate than SSAW steel pipes.

(4) There are fewer types of weld defects in ERW steel pipes than in SSAW steel pipe. Spiral submerged arc welded pipes adopt solution welding and have many types of defects. In addition to volumetric defects, there are also linear defects. ERW steel pipe welds only have line defects and are straight, making them easy to track during the inspection process. Moreover, the defects are at the maximum reflection point. Once a defect occurs, the ultrasonic wave reflects strongly and is easy to detect.

(4) The residual stress of ERW steel pipe is lower than that of spiral submerged arc welded pipe. Since the ERW steel pipe is relatively fully deformed during the deformation process, coupled with the subsequent changes in the flat and vertical ellipses and diameter reduction, the residual stress of the ERW steel pipe becomes smaller. Physical testing shows that after ERW steel pipes of the same specification and material are cut along the axis, the axial and transverse incision displacements are smaller than those of spiral submerged arc welded pipes.

(5) The overall performance of ERW steel pipes is consistent. When defects occur in the steel pipes, the steel pipes will be deemed scrapped and repair welding is not allowed. Spiral submerged arc welded pipes allow repair welding, but the performance of the repair welding is inconsistent with the overall performance of the steel pipe, and stress corrosion cracking is prone to occur in the repair welding area. Experiments have proven that the stress corrosion fatigue test life of ERW steel pipes is longer than that of spiral submerged arc welded pipes.

(6) The coating quality of ERW steel pipes is higher than that of spiral submerged arc welded pipes.

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