Seamless Steel Pipe

 　　Straight seam steel pipe refers to a steel pipe whose weld seam is parallel to the length of the steel pipe. Its production process is relatively simple. The strength of spiral steel pipe is generally higher than that of straight seam steel pipe. It can produce welded pipes with larger diameters from a narrower blank, and can also produce welded pipes with different diameters from a blank of the same width, but compared with a straight seam welded pipe of the same length, the weld length is increased by 30%-100%. The production speed has slowed down. According to its production process, it can be divided into high frequency straight seam steel pipe (erw steel pipe) and submerged arc welded straight seam steel pipe (lsaw steel pipe). The submerged arc welded straight seam steel pipes are divided into UOE, RBE and JCOE steel pipes according to their different forming methods. For most forming methods, the last process is to expand the full-length diameter of the welded pipe blank ...

　　(1) The geometrical characteristics of the straight seam steel pipe section are good, the pipe wall is generally thin, the section material is distributed around the centroid, the section has a large radius of gyration, and has strong torsional rigidity; as a compression, bending and bidirectional bending member, The bearing capacity is high, and the straightness and cross-sectional dimension of the cold-formed pipe are more accurate than the cross-section of the hot-rolled opening. 　　(2) In terms of anti-hydrodynamic characteristics, the cross section of the round pipe is the best, and the effect of wind and water flow is greatly reduced. The cross section of the rectangular tube is similar to this in this respect. 　　(3) The steel pipe is a closed section; in the case of the same average thickness and cross-sectional area, the exposed surface area is about 50% to 60% of the opening section, which is advantageous for corrosion prevention and can save the coating material. 　　(4)...

    Straight seam steel pipe fracture, hydraulic (pneumatic) parts in the design of the use of mechanical properties, brittle fracture is also related to the use of components temperature.     It has been found that when the temperature is below a certain temperature, it is found that the information will be transformed into a brittle state, and its impact absorption is significantly reduced. This phenomenon is called low stress brittle fracture in cold brittle and high strength metallic materials. In the process, the data organization is far from uniform, isotropic, there will be cracks, there will be inclusions, pores and other defects, these defects can be seen as micro-cracks in the material. Therefore, the design should also be based on the work of the component temperature to select the appropriate cold brittle transition temperature of the information.     In general, it is assumed that the information is uniform and continuous isotropic, accordi...

    Pre-welding quality of straight seam steel pipe includes seam quality and weld quality.     (1) Joint (that is, forming seam) no wrong side or wrong side is less than the specified value, the general provisions of the wrong amount ≤ 8% thickness, the maximum does not exceed 1.5mm.     (2) To ensure that the weld has a suitable penetration depth and welding volume, it is necessary to ensure that after welding does not crack, does not produce burning phenomenon, but also to control the weld height, the weld weld height does not have an impact.     (3) The weld is continuous, good shape, in order to help ensure the final external welding quality.     (4) Weld does not exist welding bias, pores, cracks, slag, burning and back welding and other defects, requiring weld center deviation ≤ 1 mm.     (5) No arc burns, splash small, does not affect the tube end groove and surface quality.     (6) Weld and base m...

    Submerged arc welding straight seam steel pipe welding introduction:     1, The bubble occurred in the middle of the weld, the main reason is that hydrogen is still in the form of bubbles hidden in the weld metal inside, so the elimination of this defect is the first step must be removed welding wire and weld rust, oil, moisture and Moisture and other substances, followed by the need to dry the flux to remove moisture. In addition, to increase the current, reduce the welding speed, slow down the melting rate of molten metal is also very effective.     2, Sulfur crack (sulfur caused by the crack). A crack in the sulfur segregation zone in the weld segregated zone, especially in soft boiled steel. The reason for this is that there is hydrogen present in the sulfur segregation zone containing low melting point iron and steel. Therefore, in order to prevent this situation, the use of sulfur segregation with less semi-killed steel or sedative steel is al...