What are the processing and technologies of straight seam steel pipes

First, what are the technical requirements for straight seam steel pipes?

According to GB3092 "Welded Steel Pipes for Low-Pressure Fluid Transportation" standard, the nominal diameter of straight seam steel pipes is 6~150mm, the nominal wall thickness is 2.0~6.0mm, and the length is usually 4~10 meters, which can be shipped in fixed length or multiple lengths. The surface of the straight seam steel pipe should be smooth, and defects such as folds, cracks, delamination, and lap welds are not allowed. Minor defects such as scratches, scrapes, weld misalignment, burns, and scabs are allowed on the surface of the straight seam steel pipe, not exceeding the negative deviation of the wall thickness. Wall thickness increase at the weld and the presence of internal weld reinforcement are allowed. Straight seam steel pipes should undergo mechanical performance tests, flattening tests, and flaring tests, and must meet the requirements specified in the standard. Straight seam steel pipes should be able to withstand an internal pressure of 2.5MPa and maintain no leakage for one minute. Eddy current testing is permitted as a substitute for hydrostatic testing. Eddy current testing shall be performed in accordance with GB7735 "Eddy Current Testing Method for Steel Pipes". The eddy current testing method involves fixing the probe to a frame, maintaining a distance of 3-5 mm between the probe and the weld seam, and using the rapid movement of the straight seam steel pipe to comprehensively scan the weld seam. The testing signals are automatically processed and sorted by the eddy current tester to achieve the testing objective. After testing, the straight seam steel pipe is cut to the specified length using a flying saw and removed from the production line via a turning frame. Both ends of the straight seam steel pipe should be flattened and chamfered, and marked. Finished straight seam steel pipes are packaged in hexagonal bundles before leaving the factory.

Second, what is the processing method for straight seam steel pipes?

Straight seam steel pipes are steel pipes with weld seams parallel to the longitudinal direction of the pipe. Their strength is generally higher than that of conventional straight seam steel pipes. Larger diameter straight seam steel pipes can be produced from narrower blanks, and straight seam steel pipes of different diameters can also be produced from blanks of the same width. However, compared to straight seam steel pipes of the same length, the weld length increases by 30-100%, and the production speed is lower. So what are the processing methods?

1. Forging: A pressure processing method that uses the reciprocating impact force of a forging hammer or the pressure of a press to change the billet into the desired shape and size.

2. Extrusion: A processing method in which steel is placed in a closed extrusion chamber, pressure is applied to one end, and the metal is extruded through a specified die to obtain a finished product with the same shape and size. It is mostly used in the production of non-ferrous metal steel.

3. Rolling: A pressure processing method in which steel billets are passed through the gap between a pair of rotating rollers (of various shapes), and the compression of the rollers reduces the cross-section of the material while increasing its length.

4. Drawing: A processing method in which rolled metal billets (shaped, tubing, products, etc.) are drawn through a die to reduce the cross-section and increase the length. It is mostly used for cold working.