In procedure qualification as per Section IX of butt braze joint of copper tubes, if the tube OD is 12.5 mm, and thickness OF 0.4 mm, base metal thickness range qualified as per QB 451.1 is 0.2 to 0.8 mm. My questions are as under.

(1) For Brazing, Pipe diamete qualification limit is not mentioned in Section IX. Why ?
(2) Qualified Weld metal thickness is mentioned for Welders. But Qualified Braze metal thickness is not mentioned in Section
IX. Why ?

Can any one explain ?