Surface NDT methods of straight seam steel selection principles: magnetic iron pipe should be used in magnetic particle testing; non-ferromagnetic steel should be used in penetration testing. Delayed cracking tendency of welded joints, the surface should be non-destructive testing after welding cooling certain time; reheat cracking tendency of welded joints, the surface should be in non-destructive testing and post-weld heat treatment once each. Surface non-destructive testing applications in accordance with the standard requirements that detects objects and applications in general as follows: (1) An outer surface of the tube material quality inspection. (2) Important butt weld surface defect detection. (3) Important fillet surface defect detection. (4) Important socket weld and jumper tee branch pipe defect detection. (5) Pipe bending surface defect detection. (6) The material tends to quench detection larger groove welded joints. (7) The design temperature is below zero or non-austenitic stainless steel pipe beveling detected 29 degrees Celsius. (8) The provisions of the double-sided weldment after weld gouging gouging detection (9) When using oxyacetylene flame cutting jig welded pipes alloy hardening tendency on when grinding parts defect detection.

1, Tube heating The average heating to stop the rapid rise and fall of temperature. To adhere to a smooth landing every time the temperature slowly, the temperature does not exceed the maximum landing 30 ℃. 2, Mandrel mill The average wall thickness of the thick-walled tubes and solid billets, so that the probability of a significant reduction in the mandrel bending deformation, can be useful for the progress of the wall thickness precision steel pipe. 3, Precision of the mandrel Mandrel outer precision control at ± 0.1mm, straight degrees mandrel deflection does not exceed 5mm. Welding, finishing pierce a pin positioned between two sections of the mandrel, in order to avoid the formation of solder total straightness deviation is too large. 4, Perfect process Perfect process, to avoid the center and pull the thin wall thickness by Haou transcend the limitations of the control condition seizures, progressive wall thickness accuracy. 5, Centering rollers Determining whether the centering roller assembly in place, adjust the rollers hold the central core, open angle and various initiatives ashamed size consistent in the middle to hold the core roll rolling line. 6, Piercing mandrel Normal Select piercing mandrel outer diameter Φ108mm-Φ114mm, wall thickness and wall thickness requirements ≥25mm average of thick-walled tube. 7, Intermediate rolling line Ensure that punch line and the middle of rolling the car in the middle perforation lines consistent and prevent "rolling on" or "rolling down" so that the tube adhere average force at the time of perforation. 8, Things rolling Head wear on the guide plate and roller rolling things to change in real time. 9, Rolling means something Roller distance, middle distance necessary to guide the rolling line. Guarantee and roll away from the guide wire in the middle of the middle of the piercing and rolling line, namely the upper and lower roller pitch equal distance about equal to the guide. In the straight seam steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate. The second key is to try to reduce the heating operation scale quantities. Especially in hot kneading the elbow, leaving the surface quality of life several things and kneading pipe, pleading even more severe.