longitudinal welded pipe refers to the steel pipe whose weld is parallel to the length direction of the steel pipe, its production process is relatively simple, and the strength of the spiral steel pipe is generally higher than that of the longitudinal welded pipe. It can produce a larger diameter welded pipe from a narrower blank, and can also use the same width of the blank to produce a different diameter welded pipe, but compared with the same length of longitudinal welded pipe, the weld length is increased by 30%-100%, and the production speed is slowed down. According to its production process, it can be divided into high-frequency straight seam steel pipe and submerged arc welded straight seam steel pipe. The submerged arc welded straight seam steel pipe is divided into UOE, RBE and JCOE steel pipe according to its different forming methods.
longitudinal welded pipe needs to carry out mechanical properties test, flattening test and flaring test, and to ensure that it meets the standard requirements. The steel pipe should be able to withstand a certain internal pressure, if necessary, perform a pressure test of 2.5Mpa, and keep no leakage for 1 minute. Eddy current test method can replace hydraulic test. Eddy current test is carried out according to GB7735 “Eddy current test method for Steel pipe” standard. The method of eddy current test is to fix the probe on the frame, keep the distance between the test rod and the weld seam 3-5mm, quickly scan the weld seam as a whole, and automatically process and classify the test signal through the eddy current test instrument. To achieve the purpose of flaw detection. After flaw detection, cut the welded pipe to the specified length with a flying saw and roll it down the line. Both ends of the steel pipe should be flat chamfered and should be marked. Before leaving the factory, the finished tubes are bundled into hexagonal shapes and packed.
There are also the following processing methods for longitudinal welded pipe:
- Forging steel, using the repeated impact force of the forging hammer or the pressure of the press to change the shape of the blank into the shape and size we need;
- Extrusion, which is a kind of metal placed in a closed extruder, applying pressure at one end to extrude metal from the specified die hole, so as to obtain a finished product with the same shape and size, mainly used for the production of non-ferrous metal materials;
- Rolling, which is a pressure treatment method in which the billet is passed through the gap between a pair of rotating rollers, and the section of the material is reduced and the length is increased due to the compression of the rollers;
- Pulling steelis a processing method of the metal blank that has been rolled through the die hole to reduce the cross section and increase the length of the metal blank. Most of this processing method is used for cold processing.
