Seamless steel pipe is the steel pipe with the largest consumption and the highest demand. The production volume and the manufacturer are the largest steel pipe types. In many cases, the competition of seamless steel pipes is relatively large and has become the main object of competition. Seamless steel pipes are widely used, and in many cases they benefit from its processing technology and process. The more important thing in processing is welding. Since welding, we must choose welding rod. Welding rod is an important guarantee for welding quality and the best guarantee for seamless steel pipe quality and use effect. The following is the selection and welding method of welding rod for seamless steel pipe we introduce to you:
Seamless steel tube welding method:
1) The seamless steel pipes connected by arc welding are constructed according to the procedures of straightening the pipe, cutting the material, beveling, grouping, welding, and cleaning the welding slag on the basis of setting out and marking.
2) Groove processing and cleaning: The cutting groove of seamless steel pipes generally adopts oxygen-acetylene flame gas cutting. After the gas cutting is completed, use a file to clean the iron oxide of the pipe mouth, and use a polishing machine to sharpen the unevenness that affects the welding quality. smooth. Small-diameter seamless steel pipes are cut with a grinding wheel cutting machine and a portable electric pipe cutting machine as far as possible, and then beveled with a grinder. The seamless steel pipe groove adopts V-shaped groove, and the groove is machined or polished with a grinder to make it smooth and even. Remove oil stains, rust and water within 20mm on both sides of the groove, and ensure that the metal luster is exposed, ensure that there are no defects such as cracks and interlayers on the surface of the groove, and remove the dirt inside and outside the groove.
3) Welding rods and flux should be dried according to the instructions before use, and kept dry during use. There is no peeling and obvious cracks in the electrode coating.
4) Nozzle pairing before welding: special pairing tools are used for nozzle pairing to ensure the straightness and alignment of the pipe. The assembly of seamless steel pipe butt welds must be flush with the inner wall, and the amount of misalignment of the inner wall should not exceed the standard; the pipe assembly should be fixed by the welder who welds the same pipe, and the welding rod or wire used for spot fixing should be the same as that used for formal welding. The spot welding length is 10-15mm, the height is 2-4mm, and should exceed 2/3 of the pipe wall thickness; the seamless steel pipe weld surface must not have cracks, pores, slag inclusions and other defects; the pipes and fittings are fixed to the point At the time, the welding area should be kept free from harsh environmental conditions (wind, rain).
5) Welding construction must be carried out in strict accordance with the welding operation instructions; safety performance and performance tests must be carried out before welding equipment is used, and unqualified equipment is strictly prohibited from entering the construction site; self-inspection and mutual inspection should be done during the welding process. Process control of welding quality.
6) The seamless steel pipe is welded by manual arc welding, and the welding rod is put into the welding rod drying box for 1-2 hours at a temperature of 100°C-150°C before use, and the surface of the welding rod is guaranteed to be free of oil stains. Pay attention to the quality of arc ignition and arc closing during welding. Ensure that the arc crater is filled at the arc crater to prevent the arc crater from cracking. Multi-layer welding can achieve staggered joints between layers. Each weld should be welded as much as possible at one time. When it is forced to be interrupted due to the help, take anti-cracking measures in time to confirm that there is no crack before continuing welding.
7) When connecting seamless steel pipes, do not forcefully match, especially when loosening the bolts at the connection part of the equipment, the counterpart should be in the correct position.
8) The butt weld or flange interface on the seamless steel pipe must avoid overlapping with the support and hanger. The opening and welding of the instrument source components on the seamless steel pipe should be carried out before the seamless steel pipe is installed.
9) The welding slag on the surface of the weld must be cleaned up, and the appearance quality inspection should be performed to see if there are welding defects such as pores, cracks, and inclusions. If there is any defect, it must be repaired in time and a repair record should be kept.
Seamless steel tubes have a hollow section and are used in large quantities as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter when the bending and torsion strength is the same. It is a kind of economical section steel. It is widely used in the manufacture of structural parts and mechanical parts, such as
oil drill pipes, automobile transmission shafts, and bicycles. Steel scaffolds and other steel scaffolds used in building construction are used to make ring parts with steel pipes, which can improve material utilization, simplify manufacturing procedures, and save materials and processing man-hours. Steel pipes have been widely used for manufacturing.
