Now we know why you missed passing the open book exam by "just one question."

Sorry, I couldn't resist the urge. You are not alone in your quandary.

Table 4.8 is for procedure qualification. The reference to clause 4.22 refers the reader to clause 4.8, not Table 4.8. Clause 4.22 requires the welder to follow the WPS and the WPS must address all the essential variables listed in clause 4.8. Clause 4.8.3 refers the reader to Table 4.8, but again, clause 4.8 is addressing the WPS, not performance qualification. However, clause 4.22 also refers the reader to Table 4.12 listing the essential variables for performance qualification.

My understanding is that if a welder follows a prequalified WPS  or a WPS qualified by testing, assuming the base metal is listed in Table 3.1, Table 4.8, or Table 4.9, the performance qualification is valid for any of the listed base metals per Table 4.12 (where a change in the base metal is not listed as an essential variable). 

To buttress my position I refer the reader to the following code interpretation:

Subject: Base Metal Qualifications
Code Edition: D1.1-90
Code Provision: Table 4.1 and Subsection 5.5.1.3
AWS Log: ID1-90-027-03
Inquiry: (1) A Group V to Group V metal of Table 4.1 weld qualification is made. Is the procedure and/or the welder qualified to weld a Group V metal to any other Group V metal listed in Table 4.1?
(2) A Group V steel to a nonlisted metal weld qualification is made. Is the procedure and/or welder qualified to weld the nonlisted metal to any other Group metal listed in Table 4.1?

Response: (1) No. Subsection 5.5.1.3 covers welding Group V to Group V base metals. However, the procedure applies only to welds made [using] the specific ASTM material specification and minimum specified yield strength as the base metal [for running] the procedure, without regard for Group number. See the example cited in 5.5.1.3. However, the welder is qualified to weld all steels in Table 4.1 by virtue of the fact that the material grouping of the steel is not a welder variable.
(2) No. Steels that are not listed in Table 4.1 require procedure qualification and the procedure only qualifies on the combination of materials tested (see 1.2.2). The welder in this situation again is qualified to weld on any Table 4.1 material by virtue of the answer given to Inquiry (1) above.

While the interpretation is dated (1990 edition of AWS D1.1), it establishes the philosophy of how the code committee thinks. I don’t believe that philosophy has changed. 

Best regards - Al