ASME IX QW-402.1 variable


QW-402.1 A change in the type of groove (Vee‐groove, U‐groove, single‐bevel, double‐bevel, etc.).


QW-402.1 is frequently addressed by adding a separate drawing of the allowable joint designs permitted by WPS, the actual joint is specified on Fabrication drawing and it should be one of the permitted joint types.

In many cases, it is acceptable to permit or specify “Groove and Fillet”, “V-Groove”, “Socket weld and grooves”, ect., in order to satisfy this nonessential variable.

Normally, all most nonessential variables leave a lot of judgments up to the manufactures when writing WPS. In some fabrication situations a change in groove design is critical (Joint weakness due to the unexpected residual stress concentrations, metallurgy changed due to two many heat circles on bigger groove ect.,). ASME IX, however, does not generally require a change in joint design to be cause for re-qualifying a WPS ( or re-running a new PQR).

Key notes:

Review Table QW-253 in general welding processes, on the Nonessential Variables. The nonessential variables are items that must be considered and addressed on WPS, however, they need not be considered nor addressed on the PQR. Note that a PQR can be in compliance with ASME IX even if nonessential variables are not addressed or are incorrectly addressed on PQR.

Come back the definition of Nonessential: ASME IX has already given the Minimum Variables that must be considered. Nonessential variables normally will not affect the mechanical properties of a weldment.

There’s no guarantee, however, the nonessential variables will not affect the mechanical properties of a weld. Because ASME IX assumes that manufactures have access to welding engineers as well as metallurgist. ASME IX is not a “How to Weld” book, but be intended to be used by who know well on welding and are familiar with welding metallurgy.

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