Seamless steel pipe is a hollow cross-section, no seams around a circular, square, rectangular steel. Seamless steel ingot is made of perforated or solid through the capillary tube, and then hot-rolled, cold-rolled or cold call is made. Seamless steel pipe having a hollow cross-section, a large number of channels for transporting fluids, such as pipes, pipe and solid steel bar, compared to the same torsional strength in bending, lighter, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, such as drill pipe, automotive drive shafts, bicycle frames and construction using steel scaffolding. Seamless steel pipe production process: hot-rolled, hot expanded, cold drawn, cold-rolled, and centrifugal casting seamless steel tubes. Seamless steel pipe specifications: 8-1240 × 1-200 mm.
Welded steel pipe refers strip or plate bending round, square and other shapes and then welded into the surface jointed pipe. Welded steel pipes used in billet steel sheet or strip. Welding methods can be divided according to different arc welded pipe, high-frequency or low frequency electric resistance welded pipe, gas pipe, stove pipe, Bundy tubes. Welded steel pipe: for oil drilling and machinery manufacturing. Furnace pipe: used as the water and gas pipe, large diameter longitudinally welded pipes for high pressure oil and gas transportation, etc; spiral welded pipe used in oil and gas transportation, Piles, piers and the like. Press seam shape classification can be divided into Longitudinal and spiral welded pipe
Longitudinal: the production process is simple, high production efficiency, low cost, rapid development. Spiral welded pipe: Longitudinal strength is generally higher than that, can narrow the billet production of large diameter pipe, you can also use the same width of the billet production of different pipe diameters. However, compared with the same length of straight seam pipe, weld length of 30 to 100%, and lower production rate.Therefore, smaller diameter pipe is mostly a straight seam welding, large diameter spiral welded pipe for the most part. By end-use is divided into general welded pipe, galvanized pipe, oxygen blowing pipe, wire casing, metric pipe, roller tube, deep well pump tube, automotive tube, transformer tube, welding thin-walled tube, welding shaped tube and spiral welded pipe. Seamless steel pipe joints and is processed in accordance with the form of division, pipe joints generally welded, cold drawn and hot rolled seamless steel pipe there are two ways
Seamless Steel Processing:
1.1, hot-rolled seamless pipe is generally automatic pipe mill production. Solid tube inspection and removal of surface defects, cut into desired length, end to end in the perforated tube surface-centering, and then sent to the furnace heating, punch in the punch. While continuing to rotate the perforation and forward, under the action of the roll and the head, the tube gradually formed within the cavity, said capillary. Continue rolling and then sent to the automatic rolling machine. Finally, after all the whole entire wall thickness were, after sizing mill
Sizing, to specifications. Continuous use of hot-rolled seamless pipe mill production is more advanced methods.
1.2. If you want to get a smaller size and better quality, seamless, it must be cold-rolled, cold drawn or a combination of the two. Cold rolled normally on two-roll mill, steel circular hole in the variable cross-section hole tapered slot and does not move the head consisting of rolling. Drawing is usually in the 0.5 ~ 100T single chain or double chain drawing machine.
1.3, the upcoming heating good extrusion tube placed in closed extrusion cylinder, perforated rod and extruded rod movement together to make a smaller extrusion extruded from the die hole. This method can produce smaller diameter steel pipe. Seamless Steel Usage: mainly used for transporting fluids or structural components.
The main use of steel pipe joints (steel) welded secondary, so the price is cheap, widely used. Seamless steel pipe used for machinery industry, pipe joints are used for the construction industry. But it involves pressure seamless steel pipes are used.
NOTE: The main difference between using:
1, pipe joints in general can withstand a maximum operating pressure less than 20 kg, which is the safest range.It is generally used for water, gas, compressed air and other low pressure fluid;
2, seamless pipe can withstand high pressure, of course, the wall thickness will also increase, which need to pressure requirements
Design. It is generally used for high-pressure pipeline equipment, boiler tubes and other high temperature and pressure. There are also structural seamless pipe, which see the design requirements.
3, there are currently some seam steel pipe seamless process, which is the weld annealing treatment to eliminate
The residual stress of the weld, the weld and base metal rather, it confined the scope of basic and fairly seamless. It may also be considered.
4, of course, there are some uses pipe joints redrawing or cored rolling after heated seamless whole market
Steel, mainly small size of the main tubes are only part of seamless in appearance, and its essence is not very good