What do 1G to 6G mean on welding tickets?

Quick answer

1G–6G are welding POSITION codes used in qualification tests (aligned with AS/NZS ISO 9606-1 and ASME practice): 1G flat, 2G horizontal, 3G vertical, 4G overhead, 5G horizontal-fixed pipe, 6G pipe fixed at 45° — the hardest, best-paid test. Note they are positions, not Australian ticket names: AS 1796 pressure certificates run as numbered classes 1–9 (by process and product), administered by Weld Australia with periodic re-validation.