The Methods of Manufacture of the ERW Steel Pipe

The time of issue:2014-6-11 10:13:45       Author:

Nowadays, the electric resistance welded pipe is accepted and used more and more widely in modern installations overseas, even if in those places where seamless pipe is considered vital. The cause of the increased acceptance of the electric resistance welded pipe is its uniform quality, dimensions and its cost advantage. The manufacturing process of the electric resistance welded pipe is as followings. The strip of the pipe mill is uncoiled, leveled and crop-sheared. Then trim the pipe on both sides at the same time to correct width, and convert it to the forming and welding line. The purpose of this process is to check for surface defects.

The cold forming rolls can be used to transform the form of the strip, and the form of the strip is usually changed into tubular form with abutting edges on top. With the high frequency ERW, the longitudinal edges can be joined. Next, heat treat the weld electrically. Some special devices are used to remove inside and outside flash from the weld so that the wall thickness of the pipe is uniform. In addition, in order to ensure enough ductility on the welded and joint area, the welded part should be heat-treated by post annealing. The diameter of the electric resistant welded steel pipe will be reduced to accurate size by a series of cold sizing rolls, which can increase strength and improve surface condition of the electric resist welded steel pipe.

Next, use a flying cut-off machine to make the length of the pipe specified. Except for the straightening operation, the ends of the pipe often need to be cropped. That whether the electric resist welded pipe should be squared or beveled depends on end finish requirements. What's more, don't forget several tests, for example, the hydrostatically test for specified pressure and the test specimens for chemical and mechanical properties. The last, we can use the ultrasonic method to inspect the each length of pipe, and the method can be similar with the check of diameter, wall thickness, surfaces, end finish, camber and concentricity. In addition, measure and record the length and weight of the pipe and apply the protective coating on the outside surface.

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