Grade and technical requirements for welding flanges
The welding flange is used in the environment where medium condition contrast is relaxed, such as low-pressure non-purified compressed air, low-pressure circulating water, its advantage lies in the cheap price comparison. The sealing surface of welding flange can be divided into smooth, concave and tenon. Smooth-type butt welding flanges have a wide range of applications, and the other two ways of butt welding flanges are also more widely used. The structure of the welding flange is reasonable, the strength and stiffness are large, and it can withstand high temperature and high pressure, repeated bending and temperature fluctuations and other harsh environment, and will not reduce the sealing performance I. The level and technical requirements of the welding flange shall meet the corresponding requirements of JB4726-4728. 1. Carbon steel forgings and austenitic stainless steel with nominal pressure PN 0.25MP-1.0MPa allow class I forgings. 2. Except for the following provisions, the forgings with a nominal pressure PN of 1.6MPa-6.3MPa shall meet the requirements of the forging grade of grade or above. 3. One of the following conditions shall meet the requirements of the forgings: (1) Forgings for the nominal pressure PN≥10.0MPa flange; (2) Chromium-molybdenum steel forgings with a nominal pressure of PN>4.0MPa; (3) Ferric body steel forgings with a nominal pressure of PN>1.6MPa and a working temperature of-20 degrees C. ANSI B16.5 WNRF 300LB DN50 flange 2. The butt welding flange is generally made of forging or forging process. When manufactured with steel plate or type steel, the following requirements must be met: 1. The butt welding flange shall be detected by ultrasonic wave without layered defects; 2. Should be cut into strips along the rolling direction of the steel, counterwelded into a ring by bending, and make the surface of the steel form the cylinder of the ring. Steel plate shall not be directly processed into a neck butt welding flange.
