OK, now I have my Section IX handy.
Two welding processes were used to weld the full 16mm (0.630-inch or 5/8-inch)thick test plate.
Each process was used to deposit 8mm (0.315-inch or 5/16-inch) of weld, i.e., 8mm with GTAW (0.315-inch or 5/16-inch)and an additional 8mm (0.315-inch or 5/16-inch)using SMAW.
GTAW can be used by itself to deposit a maximum thickness twice the thickness deposited in the test assembly: a maximum thickness of 16mm (0.630-inch or 5/8-inch).
SMAW can be used by itself to deposit a maximum thickness twice the thickness deposited in the test assembly: a maximum thickness of 16mm (0.630-inch or 5/8-inch).
The two processes can be used in combination to weld a maximum base metal thickness of 32mm (1.25-inch). Either process or both processes in combination can be used to weld the minimum thickness of 5mm (3/16-inch).
Per Table QW-451.1, make sure you review the footnotes to see if they apply.
Al