Large-diameter big thickness Grade 20# seamless steel pipe

　　Difference in allowable stress of large diameter thick wall 20 # seamless steel pipe at temperatures of 100 ℃ and 225 ℃

　　Allowable stress of No. 20 steel: allowable stress of No. 20 steel at 225 ℃: (16-36 mm) between 111-124 MPa; 117-131MPa between (6-16mm)

　　Allowable stress of 20 # steel at 100 ℃: At 150 ℃, the allowable stress of 20 # steel pipe is 130 MPa, and the allowable stress of 20 # steel forgings is 108 MPa

　　Seamless steel pipes are widely used. General purpose seamless steel pipes are rolled from ordinary carbon (C) plain structural steel, low alloy structural steel, or alloy structural steel, with the largest production, and are mainly used as pipes or structural parts for conveying fluids. 2. Supply is divided into three categories according to different uses:

　　A. Supplied according to chemical composition and mechanical performance;

　　B. Supply according to mechanical performance;

　　C. Supply according to hydraulic test. GB9948 seamless steel pipes are mainly used for the production of pneumatic or hydraulic components, such as air cylinders or oil cylinders, all of which are made of seamless pipes. The chemical components of precision seamless steel pipes include carbon C, silicon Si, manganese Mn, sulfur S, phosphorus P, and chromium Cr. GB5310 seamless steel pipes are divided into seamless steel pipes for structural purposes; Seamless steel pipe for conveying; Seamless steel tubes for boilers; High pressure seamless steel pipes for boilers. Seamless steel pipes are divided into circular and special-shaped pipes according to their cross-sectional shapes. The special-shaped pipes have various complex shapes, such as square, elliptical, triangular, hexagonal, melon seed, star, and finned pipes. Press

　　For steel pipes supplied in categories A and B, if they are used to withstand liquid pressure, they also need to undergo a hydraulic pressure test. 3. There are various types of seamless pipes for special purposes, such as seamless pipes for boilers, chemical and electric power, geological seamless steel pipes, and petroleum seamless pipes. Seamless steel pipes have hollow (zh ō ng k ō Ng) Cross section, widely used as a conduit for transporting fluids, such as oil, natural gas, coal gas, water, and some solid materials. Compared with solid steel such as round steel, steel pipes have a lower weight when their bending and torsional strength are the same, making them an economic cross-section steel. Extensively used for manufacturing structural and mechanical parts, such as petroleum drill pipes, automotive transmission shafts (composed of shaft tubes, expansion sleeves, and universal joints), bicycle frames, and steel scaffolds used in architectural construction. The use of steel pipes to manufacture circular parts can improve material availability, simplify manufacturing processes, and save materials and processing hours, Steel pipes have been widely used for manufacturing.