If a welder has several valid certs (e.g. SS; CS; Titanium; Inconel in GTAW) then that welder has to perform only one test in GTAW (within the 6 month period) and that will renew his qualifications for the GTAW process only.
ASME Code, Section IX.
QW-290.6 In Process Repair Welding
(4) continuity of qualification in accordance with QW-322 shall be based on following the WPS that was demonstrated in addition to using the process as required by QW-322.
QW-322.2 Renewal of Qualification
(a) Renewal of Qualification expired under QW-322.1(a) may be made for any process by welding a single test coupon of either plate or pipe, of any material, thickness or diameter, in any position, and by testing of that coupon as required by QW-301 and QW-302. A successful test
renews the welder or welding operator’s previous qualifications for that process for those materials, thicknesses, diameters, positions, and other variables for which he was previously qualified.
DH