Is your management getting in your way? You say "them" and I assume "they" are management. That code book will be your only ally, man. I strongly recommend you be thoroughly familiar with it. That way, when "they" tell you one thing, you can tell them how it really is. Just be a little tactful!
As for the qualification; I guess the reason for the new procedure is a job requirement in a contract? The reason I ask is because many contracts specify the code to be utilized, but do not make concessions for additional costs of procedure development, personnel qualification, etc. It also can't hurt to have the contract specify who is the EOR and what the procedure is for making changes to the weld schedules. Just a couple thoughts. Good luck, and hang in there! Not everyone wants to 1/2 @ss the job.