Both Supplementary and Non-Essential Variables

[cnkn]

Some variables in Tables QW-252 through QW-266 are marked both as supplementary and non essential variables such as QW 409.4 and QW 410.9 in table QW 253.I know that supplementary essential variables are considered only when notch toughness requirements are applied.From this point of view why all other supplementary essential variables are not also marked as non essential? To be more clear,for example,why QW 403.5 in table QW 253 is not also marked as "non essential" but QW 409.4 is marked as both "supplementary" and "non essential"? What is the difference?

 

[metengr]

Because some welding variables which directly effect impact behavior of weldments need to also be addressed in some form with no impact qualification, like polarity or current, in a WPS for information purposes. For a change in Group number this is for impact qualification only, and need not be addressed for information purposes in a WPS with no impact qualification.