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Defects and Hazard Analysis of Gas Pipeline Valve (1)

Writer:Fanny KangSource:Network Date:2017-6-1 16:43
Defects and Hazard Analysis of Gas Pipeline Valve
 
1, the valve casting process defects
 
(1) hole defects, such as stomata, shrinkage, loose, slag hole, trachoma and iron beans. They may be used in the expansion of hidden dangers. The pores are mostly distributed on the surface or near surface of the cast iron, spherical or pear-shaped; slag shape irregular, rough surface, showing a variety of different colors; shrinkage and loose was inverted cone, stomatal surface rough, mostly distributed in the casting body axis Heart parts, trachoma and iron beans are scattered in the cast iron surface. Hole defects are due to sand mold irregular or a large number of slag mixed with the defects caused by.
 
hole valve
Picture From Network
 
(2) crack defects, hot cracks and cold cracks. The hot cracks are formed at high temperatures, and cold cracks are formed at low cooling temperatures. Therefore, the former crack surface was oxidized color, crack shape twists and turns irregular; the latter crack was slightly oxidized color, crack straight, no bifurcation. They may be due to the possibility of casting chemical composition segregation or metallographic organization does not meet the minimum requirements of the CB7216-87 standard, local hard, easy to run when the pressure is not high when the valve rupture accident. So this situation should pay special attention.
 
(3) structural shape size defects, refers to the existence of more body casting meat, pouring, sand, deformation and damage defects.
 
The existence of various defects mentioned above makes the actual strength of the valve body is much lower than the theoretical calculation value, especially the crack casting defects is the valve body is not high when the fracture occurred an important reason.

TypeInfo: Technical Articles

Keywords for the information:gas pipeline valve  industry valve