Seamless Steel Pipe, referred to as seamless pipe for short, is a kind of steel pipe without seams and welded joints. Welded Steel Pipe is a steel pipe which is welded into a whole by electric welding metallurgy technology, including spiral welded pipe, long straight welded pipe, electric welded pipe, pipe joint and spiral seam welded pipe. Galvanized Steel Pipe is to coat a layer of zinc on the surface of ordinary steel pipe to protect it from oxidation corrosion.
Seamless steel pipes are produced by perforators and rolling mills. Firstly, the steel plate is processed into a mother tube, and then the mother tube is heated to a high temperature by a perforator, and the mother tube is rolled into the required seamless steel tube by using various production processes such as three-roll rolling, multi-roll rolling, piercing and rolling.
The production process of welded steel pipe includes long straight welded pipe (ERW), spiral welded pipe (SSAW), electric welded pipe (LSAW), etc. The long straight welded pipe welds the steel plate into a mother pipe through a welder, and then it is pressed by a vertical driver and a roller bed, and finally ultrasonic flaw detection and water pressure test are carried out. The spiral seam welded steel pipe is formed by bending the plate into a circle by rolling, then welding the mother pipe by submerged arc welding or gas welding, and finally forming by multi-channel control system.
The production of galvanized steel pipe is mainly to coat a layer of zinc on the surface of ordinary steel pipe to prevent corrosion. Galvanized metal can form a dense anti-corrosion layer in the atmosphere, thus protecting steel pipes from oxidation corrosion.
To sum up, there are some differences in the production technology and physical properties of seamless steel pipes, welded steel pipes and galvanized steel pipes. Seamless steel pipe has the best physical properties, but the price is higher; The price of welded steel pipe is cheap, but the weld is prone to fracture; Galvanized steel pipes are mainly used for conveying low-pressure fluids. Therefore, when choosing steel pipes, you need to choose according to your own needs and economic reality.