Technical requirements for straight seam welded pipes:
Technical requirements and inspection of straight seam welded pipes According to the GB3092 “Welded Steel Pipes for Low-Pressure Fluid Transport” standard, the nominal diameter of the welded pipe is 6~150mm, the nominal wall thickness is 2.0~6.0mm, and the length of the welded pipe is usually 4~10 meters. It can be delivered with fixed length or double length. The surface of the steel pipe should be smooth, and no defects such as folds, cracks, delaminations, and lap welding are allowed. The surface of the steel pipe is allowed to have minor defects such as scratches, scratches, dislocation of welds, burns, and scars that do not exceed the negative deviation of the wall thickness. Allows for increased wall thickness at the weld and the presence of internal weld ribs. The welded steel pipe shall be subjected to a mechanical property test, flattening test, and flaring test, and shall meet the requirements specified in the standard. The internal pressure that the steel pipe should be able to withstand, a 2.5Mpa pressure test is carried out every time, and there is no leakage for one minute. The eddy current testing method is allowed to replace the hydrostatic test. Eddy current inspection is carried out according to GB7735 “Steel Pipe Eddy Current Inspection Method”. The eddy current flaw detection method is to fix the probe on the frame, keep a distance of 3~5mm between the flaw detection and the weld, and conduct a comprehensive scan of the weld by the rapid movement of the steel pipe. The flaw detection signal is automatically processed and sorted by the eddy current flaw detector. To achieve the purpose of flaw detection. After flaw detection, the welded pipe is cut to the specified length with a flying saw and then goes off the assembly line through the overturn frame. Both ends of the steel pipe should be chamfered with flat heads, and printed with marks, and the finished pipe should be bundled and packed in hexagons before leaving the factory.
The processing method of straight seam steel pipe:
The straight seam steel pipe is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. The strength is generally higher than that of the straight seam welded pipe. However, compared with the same length of straight seam pipe, the length of the weld is increased by 30~100%, and the production speed is lower. So what are its processing methods?
1. Forging steel: a pressure processing method that uses the reciprocating impact force of the forging hammer or the pressure of the press to change the blank into the shape and size we need.
2. Extrusion: It is a processing method in which the steel is placed in a closed extrusion tube, and pressure is applied at one end to extrude the metal from the specified die-hole to obtain a finished product with the same shape and size. It is mostly used for the production of non-ferrous metals. material steel.
3. Rolling: A pressure processing method in which the steel metal billet is passed through the gap (various shapes) of a pair of rotating rolls, the cross-section of the material is reduced and the length is increased due to the compression of the rolls.
4. Drawing steel: It is a processing method in which the rolled metal billets (forms, pipes, products, etc.) are drawn through the die-holes to reduce the cross-section and increase the length. Most of them are used for cold work.
Post time: Nov-16-2022