I guess the question I would like clarification on is, what type of pneumatic test do you mean? Do you mean a simple 15 psi leak test of the welded attachment itself, or do you mean a full 1.1x design pressure pneumatic test? The latter would not make much sense to me.
I agree with pennpiper's comment "Welds to the out side of a piece of pipe that is not subject to the product under pressure or temperature but is only an external attachment does not need pneumatic testing or hydro testing." My answer was more about the 15 psi air and soap leak test, and after quickly glancing through the code again, I do not see anything stating that the 15 psi test is "required". It may just be a common practice to perform after fabrication.