Pipe flange forging technical requirements

　　1, forgings (including the forging rolling) the level of its technical requirements should be consistent with the corresponding requirements JB4726-4728.

　　1. 0.25MP-1.0MPa Nominal pressure PN is carbon steel, austenitic stainless steel forgings forging allows the use of grade Ⅰ.

　　2. In addition to the following provisions, the nominal pressure PN is 1.6MPa-6.3MPa forgings should meet Grade Ⅱ or above grade Ⅱ forging level requirements.

　　3. One of the following cases, Ⅲ and forgings shall comply with the requirements of: (1) Nominal pressure PN ≥ 10.0MPa flange forgings; (2) Nominal pressure PN> 4.0MPa chrome molybdenum steel forgings; (3) Nominal Pressure PN> 1.6MPa and the temperature ≤ -20 degrees Celsius ferritic steel forgings.

　　2, with neck butt, with neck flat welding, socket welding and threaded flange forging or forging generally use the rolling.

　　process is made. When using steel or steel manufacture, must meet the following requirements:

　　1. Steel plate shall be subject to ultrasonic testing, non-hierarchical defect;

　　2. Shall be cut along the rolling direction of steel strip, after bending butt into the ring and make rings formed on the surface of steel cylinder. Shall not be used directly machined into a steel plate with a neck flange;

　　3. Ring butt weld should be full-penetration weld;

　　4. Ring butt weld heat treatment after welding should be carried out and to make 100%-ray or ultrasonic flaw detection, and in line with JB4730-ray flaw detection of the II-level requirements, ultrasonic flaw detection of the I-level requirements in line with JB4730.

　　3. Belt neck flat welding flange, threaded flange socket welding flange and the outer slope of the neck should be no more than 7o.

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