If you've worked around pipe trades long enough, you've heard somebody say "I'm 6G certified" like it's a credential by itself. It's not. 6G is the position the test is welded in, not the certification body. The certification is AWS or ASME (sometimes API for refinery work), and the test is a coded weld in 6G position because if you can run a fixed pipe at 45 degrees, you can run any other position.
Here's the actual breakdown for the trades crowd that gets the difference.
The position numbers
- 1G: pipe rotates, weld is flat. Easy. Most apprentices start here.
- 2G: pipe is fixed vertical, weld is horizontal around the circumference. You're walking the rod around. Harder than it sounds.
- 5G: pipe is fixed horizontal, weld is uphill (or downhill) around the circumference. Vertical welding the whole way around.
- 6G: pipe is fixed at 45 degrees. You weld every position — flat, vertical, horizontal, overhead — on the same joint. This is the test that qualifies you for everything else.
- 6GR: same as 6G but with a restriction ring forcing tighter access. The "R" stands for restricted. Pipefitters in tight refinery work see this.
What "coded" means
A coded welder has passed a procedure-qualified test on a destructive sample (bend test or x-ray). The code is the document the procedure follows — AWS D1.1 for structural steel, ASME Section IX for pressure piping, API 1104 for cross-country pipeline. When somebody says "I'm coded on stainless," they mean they've passed a current procedure on stainless under one of these codes, with documentation.
The certification expires. Most run on a 6-month or 12-month renewal cycle depending on the employer's QA program. Run a job under a different procedure? You re-qualify. This is part of why pipe welders carry a stack of paper around — every cert is a separate document.
Root, hot, cap
Three pass minimum on most coded joints:
- Root — first pass laid on the prepared edge. TIG (GTAW) is common for stainless and high-purity work; SMAW with E6010 for carbon steel pipe. The root is what fails an x-ray fastest if you rush it.
- Hot pass — second layer that fuses the root and burns out any slag pockets. Run hotter and slightly faster than the root.
- Cap — final layer that gives the joint its visible appearance. Even if the cap looks like stacked dimes, what passes the x-ray is the root and the fill underneath. The cap is for the inspector and the apprentice impressed by it.
This is why old hands say things like "the cap is for the inspector, the root is for the line." A pretty cap on a bad root will still fail.
What the trades wear, and why
None of the merch in your local welding supply store is for the actual welder. It's for the apprentice or the relative buying a Christmas gift. Real coded welders wear quiet identity badges — not flame-and-helmet cartoons. Our pipe welder catalog is built around slab-serif workwear type for the guys who run root, hot, cap and don't need to advertise it.
If you've passed 6G on a coded procedure, you've already proved it. The shirt is just for the day you're not in coveralls.
— ThirdShiftPress