Control of production procedure of our factory

Designed manufacturing procedure

①Inspection of raw material pipe: Chemical analysis,surface inspection,Tolerance of W.T:+/-8%, tolerance of OD:+/-0.75%。
②Inspection of pickling and lubrication
③Inspection after cold drawing: size&size tolerance,and internal&external surface.
④Tensile test: tensile strength,yield strength,elongation,hardness,flattening
⑤Inspection of straightness:horizontal straightness by device and vertical straightness by naked eyes.
⑥Polishing&inspection:external surface check.
⑦Second cold drawing:Size&size tolerance,internal&external surface.

Instructions about OD,ID,W.T,straightness of tubes:
1. Tolerance of OD will be as per standard specification,if there no specific requirement. ID tolerance as per customers’ requirements.
2. Ovality of ID: 0.15mm max.
3. Tolerance of W.T: +/-5%
4. Straightness: 0.5mm/1000mm max for tubes below 3m, 0.8mm/1000mm for tubes between 3m and 6m,1.2mm/1000mm for tubes between 6m and 9m