Sounds like a case of "damned if you do and damned if you don't."
I think you did the right thing by asking questions when the information isn't provided. Simply asking a question is not dereliction of duty. How many disasters could have been averted if someone had asked a simple question rather than blindly following directions based on incomplete or wrong information?
On the other hand, once the question is asked and a response is forthcoming, the employee's job is to do the job as he is directed unless there is an issue with the safety of the worker, the end user, or the general public.
It is amazing how quickly managers, engineers, and inspectors develop amnesia when something goes wrong! In which case the welder is all too often left holding the bag of flaming dog poop, finger on the door bell, as the rest of the fellas beat a hasty retreat!
While it is the employee’s responsibility to follow directions, it is still management’s responsibility to provide complete and proper work instructions. Failure to provide proper work instructions is a failure on management’s part, but we all know how rare it is for management to fail at fulfilling their responsibility.
Best regards - Al