What is the ERW Steel Pipe

ERW steel pipe "is a straight seam resistance welded pipe. Electric resistance welding, abbreviated as ERW, is used to transport vapor and liquid objects, such as oil and natural gas. It can meet various requirements of high pressure and low pressure, and now it is the first in the field of transportation pipeline in the world. Key locations.


1. Welded pipe is made of steel plate welded by ERW steel pipe, LSAW steel pipe and SSAW steel pipe. In electrical engineering, "SC" is used. The utility model can be used as a thick water gas pipe or a threading pipe.
2. The wire pipe is also the wire pipe, which is relatively thin, with the word "t", and can only be used for threading.
3. ERW pipe is "high frequency resistance welded steel pipe". It is different from the ordinary welding process. The weld is made of the basic material of the main body of the steel strip, and its mechanical strength is superior to that of the general welded pipe.
ERW stands for resistance welding, which has the characteristics of high production efficiency, low cost, material saving and easy automation. It is widely used in aviation, aerospace, energy, electronics, automobile, light industry and other industries. It is one of the important welding processes.


The biggest difference between ERW steel pipe and seamless steel pipe is that ERW has welds, which is the key to the quality of ERW steel pipe. Due to the unremitting efforts of the world, especially the United States, the seamless production process and equipment of modern ERW steel pipe have been satisfactorily solved over the years.


The seamless property of ERW steel pipe is divided into geometric seamless and physical seamless.
Geometric seamless is to eliminate the internal and external burr of ERW steel pipe. Because of the structure of deburring system and the continuous improvement and improvement of cutting tools, the deburring of large and medium diameter steel pipes has been well handled. The internal burr can be controlled from about - 0.2mm to about 0.5mm.
The physical jointless means that there are differences between the metal structure and the base metal in the weld, which leads to the decrease of the mechanical properties of the weld area, and measures need to be taken to make it uniform.


During the high-frequency welding heating process of ERW steel tube, temperature distribution gradient is generated near the edge of tube blank, forming melting area, semi melting area, overheat structure, normalization area, incomplete normalization area, and one tempering area is in overheat area. As the welding temperature is higher than 1000 ° C, austenite grains grow rapidly. Under cooling condition, hard and brittle coarse phase will be formed, and the existence of temperature gradient will produce welding stress. In this way, the mechanical properties of the welding zone are formed to be lower than that of the base metal. The physical seamless property is that the welding area is heated to AC3 (927 ° C) by the local conventional heat treatment process of welding, and then 60m. The air cooling process with length and speed of 20 m / min shall be re cooled when necessary. This method can eliminate stress, soften and refine microstructure and improve the comprehensive mechanical properties of HAZ. Up to now, the advanced ERW equipment in the world has generally used this method to treat the weld and achieved good results. High quality ERW steel pipe can not only recognize the weld seam, but also realize the weld coefficient of 1, so as to realize the matching of the welding area structure and the base metal.