Surface inspection of composite panel cladding

For pipes with a large diameter, it’s possible to first weld the base layer, then the transition layer, and finally the cladding layer. In this way, all welding can be completed at the end, followed by radiographic testing and then PT testing

Hello! In response to your question, it can be answered as follows: 1. After the cladding welding is completed, a PT test should be carried out first to ensure that there are no surface defects, before proceeding with the welding of the transition layer. After all welding is completed, radiographic testing is performed to confirm the integrity of the internal structure. Under normal circumstances, if the coating is not subjected to any further surface damage during welding or as a result of operational errors, and the initial PT test is successful, there is no need to conduct another PT test after welding is completed. 2. The second method, namely welding the transition layer directly after welding the cladding, and then performing radiographic and PT inspections after all welding is completed, is also theoretically feasible. This method simplifies the operational steps, but it may increase the risk of surface defects in the coating going unnoticed, as the integrity of the coating can be affected during multiple welding processes. In summary, it is recommended to adopt the first method: after welding the cladding, conduct a PT inspection to ensure there are no surface defects, then weld the transition layer, and finally perform an RT inspection. This allows for more effective assurance of welding quality and product safety. .

I’ve learned something; thank you, master, for your generous guidance!

Question 1: Perform a PT test after completing the cladding welding, and then weld the transition layer? After all welding is completed, radiography is carried out; is a PT test still required after the radiography? Answer: Perform PT testing after cladding welding: It is reasonable to carry out PT (penetrant testing) after the cladding welding is completed, as this allows for the timely detection of surface defects. Welding transition layer: After passing the PT inspection, the welding transition layer is applied. Inspection after all welding is completed: RT (radiographic testing) is performed after welding to check for internal defects. Whether to conduct PT testing after RT depends on the process requirements and standards. If standard requirements dictate it or there is a risk of surface defects, PT testing is still required after RT. Question 2: After completing the cladding welding, proceed directly to welding the transition layer; once all welding is finished, conduct radiography, and after that perform a PT test. Is this acceptable? Answer: It is possible to weld the transition layer directly after completing the cladding welding; however, if no PT testing is performed after cladding welding, surface defects may go unnoticed. Inspection after all welding is completed: RT is performed after welding to check for internal defects. It is reasonable to perform a PT test after RT to ensure that there are no surface defects. Summary: Recommended approach: Perform PT testing after cladding welding, then weld the transition layer, and finally conduct RT and PT testing to ensure welding quality. Feasible solution: After cladding welding, directly weld the transition layer, and finally perform RT and PT inspections. However, omitting PT inspection after cladding welding may increase the risk of defects. The specific operations should comply with relevant standards and process requirements.

For composite panels, the base layer, transition layer, and surface layer should be welded first; the non-destructive testing methods to be used are RT and PT； If it is not possible to follow this sequence due to diameter or structural issues, an internal argon shielding layer, a transition layer, and a base layer can be used in sequence; the non-destructive testing methods to be employed are PT and RT ； After all welding is completed, PT can still be carried out; it should be possible to weld following the sequence of welding the base layer first.