It is the two pieces of metal joined together by welding. In QW-302.2 your weld length must be at least 6" that can be examined by the appropriate NDE.
For WPQ you have to weld a weld at least 6" in length. If qualification is by RT, the length of a pipe coupon is not important as long as the weld is 6" long.
a weld or braze assembly for procedure or performance qualification testing. The coupon may be any product from plate, pipe, tube, etc., and may be a fillet weld, overlay, deposited weld metal, etc.
I get so confused at times. I thought we were discussing the things my wife cuts from the Sunday newspaper to get a quarter off of an item she would never otherwise purchase.