Inspection personnel to implement incoming inspection before should be understanding pipe fittings manufacturing process, clear the weak link in the pipe. The scientific inspection technology and advanced inspection methods, determine the reasonable proportion of sampling and testing focus, effectively play the role of quality control and check.
Elbow for changing the direction of the pipe fittings, seamless elbow and welded elbow, the seamless elbow mostly adopt hot pushingpipe method manufacturing is straight pipe set on the mandrel, mandrel head for bending of the core head (or horn shaped core head), ox horn core head by induction heating, the external forces are applied at the other end of the pipe section, in the induction heating and under the action of external force, straight pipe push made certain curvature radius of elbow. Mainly to the welded elbow plate is pressed into a certain shape and then welded. Can also be used to push and seamless steel pipe.
According to the manufacturing process of the seamless elbow, the outer side of the elbow is in tension stress state, and the wall thickness is easy to be thinned, the inner side is in the stress state, and the wall thickness is easy to be thickened or folded. For weld elbow, the weld seam is a complex part of stress distribution, which is easy to produce crack and weld defects.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)