It is not uncommon to experience cold starts when using GMAW on aluminum and crater cracks are a common occurrence. If I'm not mistaken, D1.2 used to allow for a crater crack when making an intermittent fillet weld provided the crack is confined to the crater and the requirement for the length has been met. That is to say the intermittent fillet weld is longer than required so that the crater crack is not included in the minimum length. That was changed in the 2003 edition to say "shrinkage" is permitted provided it is contained within the crater. Shrinkage in my mind is the "crater crack" prevalent in GMAW welds on aluminum. In my opinion the word "shrinkage" is not well defined and open to interpretation.

As is the case with AWS standards and codes, the responsible design professional, i.e., EOR if you are dealing with a building, can modify the requirements of the applicable standard provided the owner/customer is in agreement. As per clause 1.1, a change, modification, or interpretation is within the scope of the engineer's prerogative. Remember, the engineer as used by the code is the owner’s representative, not the fabricator’s engineer.

This would be one of those situations where clarification is warranted. A technical inquiry would be the route to follow if the situation is such that the fabricator, engineer, and owner could not come to a mutual agreement.

Best regards - Al