I am currently reading AWS D1.6 1999 cover to cover and I am new to this site. I cannot find anything about welding certification within it. Is a welder required to have been certified to perform the welding? If so, what are the requirements?
As "henri2" noted above his reference is correct. Also remember the WPS that the welder is using must either be "prequalified" or qualified under Section 3 or Section 4, respectively.