Stainless steel tube is a hollow round steel bar, mainly used in petroleum, chemical, medical, food, light industry, machinery and instruments and other industrial pipes and mechanical structural components. In addition, bending, torsional strength of the same, lighter, so it is widely used in the manufacture of mechanical parts and engineering structures. Also used in producing all kinds of conventional weapons, the barrel, shells and so on.
Stainless steel seamless pipe manufacturing process at a temperature of 2200 ° f punched a hole in the stainless steel billet, and at this temperature, tool steel becomes soft and drawing stamped and formed from spirally Kong Zhongcheng. Such non-uniform wall thickness of the pipe and eccentric high. Thus astm allow seamless tube wall thickness difference than to have a large difference in the thickness of the pipe joints. Pipe joints is (4-5 feet per roll width) made by precision cold-rolled sheet. Cold-rolled sheet is usually the biggest difference between the wall thickness of 0.002 inches. Steel plate was cut into a width of πd, where d is the outer diameter of the pipe. Slit pipe wall thickness tolerance is small, and the entire circumference of the wall thickness is very uniform.
2. Welding Performance
Usually there is a chemical seam and seamless tubes have some differences. Production of seamless steel components simply meet the basic requirements of astm. It produced the steel pipe joints contain chemicals suitable for welding. Such as silicon, sulfur, manganese, oxygen, and other elements of the triangle ferrite produces an easily transferring heat weld material during the welding process by mixing a certain proportion, so that the entire weld penetration. Missing more than the chemical composition of the steel pipe, seamless pipe, for example, the welding process will produce a variety of uncertainties, not easy to weld and solder impervious.
3. Grain Size
Metal grain size and heat treatment temperature and time to maintain the same temperature related. Annealed stainless steel pipe joints and seamless stainless steel pipe as grain size. If the pipe joints with a minimum of cold treatment, the weld on the grain size is smaller than the grain size of the weld metal, otherwise, the grain size is the same.
4. Pipeline Strength
Pipeline strength depends on the alloy composition, which contains the same alloy and the same heat treatment of stainless steel tubes and seamless stainless steel pipe joints essentially consistent intensity.
After the three-dimensional vibration test and pull test, stainless steel pipe joints tear occurs almost exclusively in the area away from the welding point or heat the place. This is because the weld fewer impurities and the nitrogen content is higher, and thus the strength of the weld is better than the other region. However, ASME believes stainless steel pipe joints can only bear 85% of the allowable pressure, mainly due to the collection of data as early as from the improved welding equipment in use today.