pwht for clad pipe

[sadra]

hi,
in our project we have api 5l x65 cladded with 3mm inconel
625 the thk of carbon steel portion is more than 19mm in this case pwht is require or not.
regards
r.salimi

 

[GRoberts]

Since this question is more on the design end, you might try posting it in the ASME forum if it is an ASME application, or the API forum, etc.

 

[sayee1]

Like Groberts said, the ASME forum if it is an ASME application, or the API forum might be better forumes.
A few questions/assumptions:
1. Since API 5L X65 pipe specified, I presume it is for fabrication of piping as per ASME B31.3.
2. You are asking about the PWHT, but have not specified the joint design. You can have the butt joint welded directly between two clad API 5L X65 pipes with inconel consumables with backing gas for the root, or have "strip back of cladding" to ~ 10mm on either side of bevel, followed by cs welding from the side opposite to the clad, followed by restoration of cladding. Or it could just be the clad restoration on the ID of the pipe..... Please specify.

In any case, the client specification gives the requirement for PWHT in most cases over and above code requirements and that is binding. However based on my experience, normally, the PWHT is required for the welding of butt joints with the nominal weld thickness exceeding 19mm(Sometimes the client specification also specifies the requirement of PWHT or CTOD in lieu of PWHT only if the weld is cs and not if the weld metal is inconel). In case of just clad restoration or weld overlay, there is no requirement for the PWHT. However, if the clad pipe is going to be welded to a flange say such that the nominal weld thickness is in excess of 19mm, there may be parts of the weld which are undergoing PWHT, parts which are not depending on the method of the PWHT. So the weld procedure has to be qualified in that case for either scenario.


A better understanding of why the PWHT is required would help you understand the code spec requirements.
Thanks and regards
Sayee Prasad R
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Mob: 00971507682668
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