Hi qcweld!
First off,
"WELDCOME TO THE WORLD'S GREATEST WELDING FORUM!!!:) :) :)" Now that I've got that out of the way...
Need more info... Such as what materials are are you working with, what is the governing code or standard, application, intended service etc.
In other words, please provide us with as much information related to your query as you possibly can so we can give you an informed response or as close to one as possible. ;)
Respectfully,
Henry