Can radiographic testing be performed on welds that have already been surfaced?

For safety reasons, flaw detection should

This post was last edited by xhndt1963 on 2017-7-2 09:03. From the perspective of inspection personnel, such welds can be subjected to radiographic testing, and the results are evaluated in accordance with relevant standards. Two things need to be achieved: first, the energy of the radiographic device must be sufficient to penetrate the base material and the surfacing layer; second, the location of the weld seam on the surfacing layer needs to be roughly marked.

1. From the perspective of component compression, the base metal withstands internal pressure, while the surfacing layer provides corrosion resistance. Typically, manufacturing units only perform RT on the base layer during the production process; if issues arise, repairs are carried out, and since it is the same metal, the repair process is simple. For the surfacing layer, a PT test is conducted; it is sufficient as long as there are no defects exceeding the specified limits on the surface. 2. When a thorough inspection of the products after use is carried out, RT testing is necessary to examine the entire thickness, and many manufacturing defects will be detected, with these defects mainly occurring in the surfacing layer. When the defect exceeds the limits, it is considered unqualified from the perspective of weld evaluation. Whether repair is necessary at this point depends on the user’s evaluation and decision. 3. To avoid future problems, it is necessary to clarify during the manufacturing process that full responsibility for the weld thickness will be assumed. One approach is to perform RT in two steps, once after the formation of the base weld and once after cladding ； Another approach is to conduct one RT test after all welding is completed, but if defects are found, it becomes more difficult to carry out repairs, and the impact of alloy composition dilution must also be taken into account; therefore, a suitable repair process should be employed

Non-destructive testing cannot replace strength testing

This also falls under the category of cases where a hydrostatic test cannot be carried out due to special reasons.

RT testing can be used; if defects exceeding the limits are detected, it is necessary to determine whether they are located in the base layer or at the joint. TOFD testing can also be employed.

This post was last edited by wanlirn on 2017-7-7 at 18:23. This does not fall under the category of situations where a strength test cannot be carried out (I don’t understand what the relationship is between temper brittleness and water as a medium); it’s just that water cannot be used – can’t other media be used to apply pressure instead? I don’t know how you modified this equipment. Was welding done? Yes, welding was done, and strength tests must be carried out. You work in equipment design, right? This aspect needs to be strictly followed

If there is a surfacing layer, RT is possible, but it becomes more complicated in terms of defect detection. May I ask why, in order to avoid the effects of temper embrittlement, a hydrostatic test cannot be carried out after the modification? ”

Materials of the 12CR2MO1 type that are used over a long period at temperatures between 315 and 593 degrees may develop temper brittleness. If the temperature is below the ductile-brittle transition temperature, brittle failure may occur when the stress reaches a certain level; this can be avoided if the stress level is less than 1/5 of the yield strength. In engineering practice, it is generally ensured that the temperature remains below 93 degrees, with the pressure not exceeding 25% of the design pressure. Including hydrogenation reactors, hydraulic testing should be avoided after long-term use.

Radiographic testing can be performed on the weld joint to detect internal defects in it； The base metal area can be subjected to ultrasonic testing and penetrant testing to detect non-interpenetrating defects and surface opening defects.