QW-402.1 A change in the type of groove (Vee‐groove, U‐groove, single‐bevel, double‐bevel, etc.). Please see the interpretation: ASME IX QW-402.1 variable
QW-402.4 The deletion of the backing in single welded groove welds. Double‐welded groove welds are considered welding with backing. Please see the interpretation: ASME IX QW-402.4 variable
QW-402.5 The addition of a backing or a change in its nominal composition.
It is used when the EB insert – fusible backing, incorporated with weldment in GTAW.
QW-402.10 A change in the specified root spacing. Please see the interpretation: ASME IX QW-402.10 variable
QW-402.11 The addition or deletion of nonmetallic retainers or non-fusing metal retainers. Please see the interpretation: ASME IX QW-402.11 variable
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 manufacturers have access to welding engineers as well as a metallurgist. ASME IX is not a “How to Weld” book, but be intended to be used by those who knows well on welding and are familiar with welding metallurgy.