Hello Joey;

Not to be argumentative, but AWS A5.18 is the specification, not classification.

AWS A5.18 includes a number of electrode classification that includes ER70S-2, ER70S-3, ER70S-6, to name a few. It also includes the classification ER70S-G for those electrodes that do not met the specific chemistry of one of the listed electrodes. Since electrode classification is a nonessential variable except in the case of notch toughness, I can see where some sections of the Boiler and Pressure Vessel Code may allow the contractor to switch from one classification to another, but the contractor should understand the implications of doing so. The switch from one classification to E70S-G should not affect the minimum ultimate tensile strength of the welded joint, but there may be other factors to consider.

Best regards - Al