Valves with inconel overlay for sour service as per API 6D

1. PWHT is not a requirement for the clad/overlay itself. Hence for a clad component (with any cs thickness, for e.g. even 200 mm wall thickness and typical 3mm clad), with the part not going to be butt welded to any other part (for ease of understanding, say for e.g. a blind flange), there would be no need of PWHT for the overlay or the weld procedures used for the overlay. 3. However if one clad component is going to be welded to another clad component (For e.g. a clad pipe to clad flange) in such a way that the nominal weld thickness at the weld joint exceeds 19mm (for a valve fabricated in line with requirements of B31.3/API 6D), it would necessitate the PWHT of the joint and thus the clad/overlay shall also see PWHT. The WPS/PQR requirements then depends on the fabrication methodology as follows:
a. If the entire fabricated spool, is going to undergo the PWHT after butt welding (putting the fully fabricated spool inside a furnace) WPS with PWHT only should suffice
b. If only the weld joint and adjoining area (PWHT using electrical resistance pads) is going to undergo PWHT, WPS with PWHT as well as WPS without PWHT(As welded) would be necessary.


Your interpretations/suggestions/comments on the above please.


Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
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