Must the longitudinal ring welds covered by the coiled tubing be subjected to 100% RT inspection?
Thread Content
The cylinder inspection ratio specified on the drawing is 20% RT, with grade III as the acceptable standard. However, it was specified in the non-destructive testing requirements that 100% RT inspection must be carried out on the areas where the welds are covered. So far, 20% of those covered areas have been inspected according to the drawings; it’s not clear whether this meets the acceptance criteria, and what additional remedial actions can be taken
The covered areas must achieve 100% RT in accordance with the drawing requirements; if 100% RT is not achieved upon completion, it certainly does not meet the regulatory specifications. As a result, the inspection by the special inspection agency will not be approved, and no certificate will be issued. As a remedy, first ask the flaw detection engineer whether RT scanning can be added in the areas that have not been inspected. If it’s not feasible to add such scanning, you need to communicate with the special inspection agency to see if they have any suggestions. If no effective remedy is available, the only options are to repeat the process or conduct flaw detection on the cut points of the coil; only after it passes the inspection can the coil be used, taking into account the impact of welding on the material quality.
The specification stated on the drawing is 20% RT
But the area covering the longitudinal circumferential weld must be 100%
Let’s extend the question: what about jacketed vessels?
I also want to ask: ours comes with a jacket as well as an insulation layer
I didn’t explain it clearly enough: this device features an outer tube that covers the longitudinal seam of the inner pot, with an additional jacket outside that outer tube, and a insulation layer further outside the jacket. The drawing specifies 20% RT for the cylinder and jacket cylinder, and 100% PT for the half-pipe welds.
First of all, we need to understand that by \"coverage\" as referred to in the standards, is meant tight coverage – that is, after using reinforcement rings, gaskets, internal components, etc., the welds are basically not visible. If there are problems with the welds, it becomes impossible to detect them. Therefore, for safety reasons, flaw detection is necessary. From your description, it seems that the external half-pipe should be welded to the cylinder body, in which case flaw detection is required; if the pipe is installed entirely on the outside, then flaw detection may not be necessary. If an irreversible jacket is added on the outside, then 100% flaw detection is essential.
The covered welds must be inspected 100%.
GB150----Page 335