Welders in the United States earned a median wage of about $53,750 per year in 2025, according to the Bureau of Labor Statistics (see how much do welders make), and the spread above that median tracks closely with documented skill: position, process, and code.
The AWS D1.1 3G vertical-up plate test is one of the most common tickets shop foremen and structural contractors ask to see. It qualifies you for flat, horizontal, and vertical groove welds on carbon steel using MIG Welding, and it separates wire-feeders who can only run flat from welders trusted on structural joints.
Passing hinges on a chain of small decisions: coupon prep, machine settings, a clean root, controlled fill passes, a tight cap, and a bend coupon that opens without cracking.
What Is a 3G MIG Welding Certification?
The 3G position refers to a vertical-up groove weld made on a flat plate standing on its edge. Instead of welding flat on a table or overhead, you're running weld beads upward against gravity, controlling puddle sag while maintaining penetration and bead shape. It's one of the more demanding plate positions in the AWS D1.1 structural welding code, which is why passing it carries real weight on a resume.
Why Employers Value This Certification
A documented 3G welder certification tells a hiring manager you can handle out-of-position work, not just flat-and-easy joints. Structural fabrication, pipe support work, and many field construction jobs require vertical welding on a regular basis. Certification removes the guesswork: instead of asking a candidate to prove skill on day one, employers can trust a welder who already holds a current AWS D1.1 3G qualification. It can also lead to higher pay grades and union apprenticeship advancement, since many outfits tie wage steps directly to position qualifications.
MIG Is the Process, Not the Limit
GMAW (commonly called MIG Welding) is the welding process used for this specific test, but the certification itself is procedure-based rather than process-exclusive. In other words, you're certifying to a specific welding procedure specification (WPS) that defines the process, position, material, and filler metal combination. If your employer's WPS calls for GMAW in the 3G position, that's what you'll test on, but the underlying code doesn't limit you to MIG forever. Many welders later add stick or FCAW welding certification using the same positional logic.
One Test, Multiple Positions Covered
Under AWS D1.1's qualification range rules, passing the 3G vertical-up test typically qualifies a welder for flat (1G) and horizontal (2G) groove positions as well, since vertical-up is considered more difficult and covers the easier positions by default. That makes the 3G test an efficient investment: one certification test, three positions covered.
AWS D1.1 3G Test Overview: Coupon Dimensions and Qualification Range
The standard backed 3G test coupon under AWS D1.1 is 3/8 in (10 mm) plate, beveled to a 45-degree included groove angle, which works out to 22.5 degrees per side. That geometry is the baseline most testing facilities and union halls set up for a vertical-up plate test, and it is the setup assumed throughout.
Coupon Dimensions and Joint Prep
Two plates are beveled, tacked to a backing bar, and held with a 1/4 in root opening. The gap is not decorative: it gives the wire enough access to fuse the root faces to the backing, which is exactly where most test failures start.
- Plate thickness: 3/8 in for the common backed groove coupon.
- Groove angle: 45 degrees included, 22.5 degrees per side.
- Root opening: 1/4 in with backing in place.
- Backing bar: typically 1/4 in minimum to 3/8 in maximum thick, mild steel of the same general material group as the base plate.
- Backing width: 3 in minimum when the backing stays in place, or 1 in minimum when it is removed for radiographic testing.
Check these numbers against the written procedure your testing facility hands you before you strike an arc. Some shops run open-root variants with a tighter gap, and that is a different joint entirely, with different MIG welder settings and different MIG welding techniques.
What the Test Qualifies You For
Position coverage is the part welders most often get wrong. Passing 3G qualifies you for flat, horizontal, and vertical plate work. It does not cover overhead. All-position plate qualification normally means passing 3G and 4G welding certification together, so if your employer wants a welder who can run anything on the shop floor, expect to test twice.
Thickness coverage tracks the coupon. For coupon thicknesses from 1/8 in up to just under 1 in, the code-style range qualifies from 1/8 in minimum to twice the coupon thickness maximum. A 3/8 in coupon therefore covers 1/8 in through 3/4 in material. That ceiling matters if you are chasing structural work on heavy sections: a 3/8 in test will not put you on 1 in plate. Welders who need unlimited thickness coverage test on thicker coupons, and that is a conversation to have with your certified welding inspector before you pay the test fee.
Machine Setup and Settings for Vertical-Up MIG
Starting points vary by machine, wire diameter, and test coupon thickness, but most successful 3G vertical-up MIG tests use controlled short-circuit transfer for the root and fill passes. The table below separates short-circuit and pulsed spray settings commonly referenced for 3G plate tests. Treat these as starting points, not fixed values; always adjust to your specific machine, joint fit-up, and welding position.
| Parameter | Short Circuit Setting | Spray/Pulsed Setting | Notes |
|---|---|---|---|
| Voltage | 17 to 19 V typical; 21.6 V root and fill, 22.4 V cap reported in specific 3G tests | 22 to 26 V; one forum report notes successful vertical-up pulsed spray at 18 to 19 V on a CV machine | Reduce flat-position voltage and amperage by 10 to 15 percent for vertical-up, then fine-tune. .035 in wire short-circuit vertical-up often starts near 18 V with 15 to 21 V spread. |
| Wire feed speed | 150 to 250 IPM | 300 to 400 IPM | Adjust wire feed speed to match voltage and plate thickness. Pulsed spray moves more wire and requires a higher wire feed speed for stable transfer. |
| Wire diameter and type | 0.035 in ER70S-6 | 0.035 in ER70S-6 | Standard filler metal for mild carbon steel 3G tests. Use a clean, dry spool and correct drive rolls for the wire diameter. |
| Shielding gas | 75 percent argon / 25 percent CO2 | 75 percent argon / 25 percent CO2 (or pulsed spray gas specified by WPS) | Mixed gas supports stable short-circuit and pulsed spray transfer. Confirm the exact blend with your welding procedure specification. |
| Gas flow rate | 25 to 35 CFH | 25 to 35 CFH | Miller mild-steel vertical-up guidance lists 20 to 25 CFH. Open-root 3G tests may require the upper end of this range for adequate shielding. |
| Contact tip to work distance (stickout) | 3/8 to 1/2 in | 3/8 to 1/2 in | Keep stickout steady during the pass. Generic MIG guidance applied to vertical-up reports 10 to 15 mm, which overlaps the 3/8 to 1/2 in range. |
Step-By-Step Pass Sequence: Root, Fill, and Cap
How should the root, fill, and cap passes actually be run on a 3G vertical-up MIG welding plate so the weld passes visual and bend tests without undercut or excess reinforcement? The sequence matters less than consistency, but each pass has a specific job.
Root Pass: Lock In Penetration and Tie-In
Before striking an arc, confirm the coupon matches the WPS: a 1/4 to 5/16 inch root opening, a 45 degree included groove angle, and a minimum preheat of 60°F. A common vertical-up MIG starting point is 21.6 volts and 155 amps with wire feed near 340 and 25 CFH shielding gas, but adjust within the procedure limits.
Hold the gun at a 10 to 15 degree drag angle or slight push angle depending on the WPS, and keep the arc tight. Use a tight side-to-side weave with a brief pause on each sidewall to fill any tendency toward undercut. A small whip may be allowed by some procedures, but a controlled weave is usually safer for vertical-up. Let the puddle keyhole and wet into the edges. Travel slowly enough to penetrate the root, but do not linger in the center or the puddle will sag.
Fill Passes: Build Without Sag or Hump
Clean the joint between every pass. A wire brush is often enough, but use a grinder after the root to remove any silicon islands or trapped slag before the next pass.
Run fill passes as stringers or a small triangular weave unless the WPS specifies otherwise. Keep the weave width to about three times the MIG welding electrode diameter, moving through the center quickly and pausing at the edges for tie-in. Maintain interpass temperature within the WPS limits. Many 3G procedures allow a maximum interpass of 400°F, while some qualified WPSs permit up to 450°F, so check the procedure before welding. A puddle that is too cold tends to hump; too hot and it will undercut or sag , both are classic MIG Welder Troubleshooting symptoms.
Cap Pass: Profile, Not Bulk
For the cap, use 2 to 4 stringer beads or a slight weave no wider than 3/4 inch. Hold a 5 to 10 degree push angle and pause briefly at the toes to avoid undercut. Travel fast enough to prevent excess reinforcement, but slow enough to wet the toes. The finished cap should have no undercut or overlap, and reinforcement should remain within code limits.
Clean the cap before inspection. The final pass is not about adding bulk; it is about leaving a smooth, code-compliant profile.
The 3G Certification Process at a Glance
On test day, the 3G MIG certification follows a pass-by-pass sequence. Each stage builds on the one before it, and the final visual and bend tests confirm that the weld is structurally sound.
Preparing and Testing the Coupon: Visual Inspection and Bend Test
Once the cap pass cools, the test plate becomes a coupon that must survive cutting, inspection, and bending before anyone calls you certified in MIG welding. This is the moment where a good-looking weld either proves itself or gets exposed through destructive weld testing.
Cutting the Specimens
The examiner sections the plate into four bend specimens: two face bends and two root bends. Each is typically cut to about 1.5 inches wide and 6 inches long, with reinforcement and backing ground flush so the specimen thickness matches the base metal.1 Corners get eased to a radius no greater than 1/8 inch,1 and the root or face side is marked before grinding so nobody loses track of which surface faces outward during the bend.
Visual Check Before Bending
Before any specimen goes into the jig, it gets a visual pass. There should be no cracks anywhere in the weld or heat-affected zone. Undercut is limited to 1/32 inch, and reinforcement (the crown height left standing above the plate surface) can't exceed 1/8 inch.3 A specimen that fails this check never makes it to the bend jig at all, since bending a cracked coupon just confirms what visual inspection already found.
Running the Bend Test
Each specimen gets clamped into a guided bend jig and forced into a U-shape through 180 degrees. The plunger that pushes the coupon into the die typically has a diameter in the neighborhood of 1-1/2 inches for standard mild steel base metal,2 though tooling can vary by yield strength on some setups. The weld sits centered in the die so the bend stresses it evenly across the joint.
Reading the Results
After bending, the examiner inspects the convex, or outer, surface,4 which is now the tension side and the one most likely to reveal hidden problems. Acceptance requires no single discontinuity longer than 1/8 inch in any direction, and the combined length of smaller discontinuities (over 1/32 inch each) can't exceed 3/8 inch total.3 Corner cracks get a little more leeway unless they trace back to slag inclusion or a fusion-type flaw, in which case the tighter 1/8 inch limit applies.3
Most bend failures trace back to porosity trapped during fill passes or lack of fusion at the sidewalls, both of which open up dramatically once the metal is stressed and folded.
Certification pays. Industry data compiled in a 2026 certified welder career guide indicates that welders holding AWS certifications can earn roughly 30 percent more than uncertified welders doing comparable work. A single 3G plate test, passed on a Friday afternoon, can shift your earning bracket for years.
Related Articles
Welding Workforce Size
Common Questions About 3G MIG Certification
Here are the questions welders ask most before a 3G vertical-up MIG test. The answers reflect common AWS D1.1 structural practice and typical test setups, but your facility's WPS and qualification rules control the final details.
- What are the dimensions of a 3G MIG welding test coupon?
- There is no universal coupon size for a 3g weld test. Confirm the governing code and the facility WPS before cutting. In a common AWS D1.1 kit setup, beveled plates are 3/8 in thick, 4 in wide, and 7 in long, with a 3/8 x 1 x 8 in backing bar. Other kits list raw pieces at 3/8 x 3 x 7 in, and plate length often ranges from 7 to 10 in.
- What settings should I use for vertical-up MIG welding?
- Start from a qualified WPS for MIG Welding, not a generic chart. When no procedure is specified, a common starting point is to reduce wire feed speed about 10 to 15 percent from flat and reduce voltage about 1 to 3 volts, while staying hot enough for sidewall fusion. One published example moves from 300 IPM and 19 V flat to 255 IPM and 16 V vertical up. Fine tune on practice plate.
- Does passing a 3G test qualify me for 1G and 2G positions?
- Under commonly cited AWS D1.1 position tables, a 3G groove test typically qualifies you for 1G, 2G, and 3G groove welds, plus 1F, 2F, and 3F fillets. It does not qualify overhead 4G groove welding. Exact coverage depends on the AWS D1.1 edition, process, thickness range, backing, and essential variables in your WPS, so verify with your employer or jurisdiction.
- How do I avoid undercut on a 3G cap pass?
- Keep the puddle small and the arc tight with consistent contact tip to work distance. Use Cap Welding Techniques such as a controlled triangle weave with deliberate pauses at each toe, move faster across the center, and clean between passes. If the puddle is too fluid, reduce wire feed speed or voltage slightly. Check gas flow and cleanliness before changing electrical settings.
- What is the difference between 3G and 3F welding positions?
- 3G is a vertical groove weld on a butt joint, deposited upward for qualification. 3F is a vertical fillet weld, usually on a T, lap, or corner joint. A 3G test often covers 3F under common AWS D1.1 rules, but fillet qualification is not automatic under every code or employer.