Welding neck flange

Welded flange is a pipe fitting, refers to with a neck and a circular tube transition and pipe butt welding flange.Butt welding flange is not easy to deformation, good sealing, wide application, have corresponding rigid and elastic demand and reasonable butt thinning transition, joint good distance away from the joint face the faying surface from welding deformation temperature.

Scope of application

Butt welding flange is not easy to deformation, good sealing, wide application, have corresponding rigid and elastic demand and reasonable butt thinning transition, joint good distance away from the joint face the faying surface from welding deformation temperature, it take more complex syndromes beep form structure, suitable for pressure or temperature fluctuations of pipeline or high temperature, high pressure and low temperature pipes, commonly used in PN is greater than 2.5 MPa pipe and valve connection;Also used to transport is expensive, inflammable, explosive medium on the pipeline.

The technical requirements

A, butt welding flange level and technical requirements shall be in accordance with the corresponding requirement of the JB4726-4728.

1, the nominal pressure PN 0.25 MP 1.0 MPa carbon steel and austenitic stainless steel forgings allowed the use of level Ⅰ forgings.

2, in addition to the following provisions, nominal pressure of PN 1.6 MPa to 6.3 MPa forgings shall conform to Ⅱ level or above level Ⅱ forgings levels.

3, conform to one of the following should accord with the requirement of Ⅲ and forgings: (1) nominal pressure PN acuity 10.0 MPa flange forging;(2) the nominal pressure PN > 4.0 MPa chrome molybdenum steel forgings;(3) the nominal pressure PN > 1.6 MPa and working temperature - 20 degrees Celsius or less ferritic steel forgings.

Second, the butt welding flange generally made by forging or forged technology.When manufacturing steel plate is used, must meet the following requirements:

1, butt welding flange should be by the ultrasonic testing, no delamination defects;

2, should be along the direction of steel rolling cut into strips, the bending welded into a circle, and to form the surface of the steel ring cylinder.Shall not adopt steel plate machining directly into with butt welding neck flange;

3, circle the butt weld of full penetration welds should be adopted;

4, the butt weld in ring should be heat treatment after welding, and 100% ray and ultrasonic flaw detection, and radiographic conform to the requirements of the JB4730 of class II, ultrasonic testing conform to JB4730 class I requirements.

Third, the neck butt welding flange lateral slope should be not more than seven o.Butt welding flange in the production strictly control technology and welding parameters, guaranteed to give full play to the role and value in the production and use.