Hi, I have a query regarding inspection approach different consultants follow in terms of alloy steel pipe welds mainly P11 and P22 pipes. We have come across a spec where it insists 100% radiography all the weld joints for all alloy steel joints. We have also worked in similar projects where alloy steel piping with same criticality had only 25% radiography if it follows the same WPS and carried out by same welders. Is it wise to have 100% RT for alloy steel? And also, it is worth having second RT or UTI after heat treatment on such joints? regards

Thanks regards

I dont agree with Ashfaq, P11 and P22 needs critical control pre, during and post welding. These material depending upon J and X factor are susceptible to delayed hydrogen cracking and temper embrittlement. This careful NDT control is required. RT is suggested minimum 72 hrs after welding. In normal practice no welding team is 100% full proof and thats why careful NDT is desired. UT is often dictated by QC Inspectors and Consultants as an ultimate NDT after PWHT as UT can detect finer cracks which can generate in P11 and P22 material due to material chemistry, impurities and lack of control in welding / PWHT. Thus it is better to keep 100% RT followed by UT as best engineering practise but depending on service criticality and cost of failure impact on Plant and Management this need to be decided by the Inspection and Planning team. regards >1. It is advisable to have 100% RT on all weld joints in P11 >or P22 material whatever the weld joint thickness and type >is. It may be waived off on socket welds having throat >thickness below 8 mm provided they have not to be operated >in hydrogen service. >2. What we have experienced is that UT after PWHT on P11 or >P22 does not yield any finding. You just need to monitor >PWHT in the right way. But yes on P5 and P9 having higher >chromium content, this should be the practice to conduct >100% UT after PWHT as probability of crack initiation during >PWHT is higher due to higher Cr content. > >Hope this would help. > >Regards, >Ashfaq Anwer >http://forums.thepetrostreet.com