1G, 2G, 5G, 6G Pipe Welding Positions Explained

Pipe welding uses four position designations: 1G (rolled), 2G (horizontal fixed), 5G (horizontal pipe, vertical fixed), and 6G (45-degree fixed). The positions get harder as the numbers climb, and each one tests your ability to handle different gravity challenges on a curved joint. The 6G position is the industry standard certification test because passing it qualifies you for every other position.

Pipe positions differ from plate positions because the joint wraps around a circle. You can’t just weld in one orientation. Even a “flat” pipe weld transitions through multiple positions as you work around the circumference, unless the pipe is rolling.

1G: Rolled Pipe

In 1G, the pipe rotates while you weld. Your torch or electrode stays at the 12 o’clock position (or slightly past center), and the pipe turns beneath it. You’re always welding in flat position.

Setup

• Pipe sits in a set of rollers or a positioner that turns at a controlled speed
• The weld axis is horizontal
• Rotation speed matches your travel speed

Technique

• Standard flat-position settings and technique
• Watch the puddle at the 12 o’clock to 1 o’clock position
• If the rotation is too fast, the bead gets thin and undercut appears at the toes
• If it’s too slow, the bead gets fat and can drip at the top

When It’s Used

• Production pipe welding (pipe spools in a fabrication shop)
• Any situation where the pipe can be rotated mechanically
• Not used for field welding on installed piping

Certification Scope

1G pipe qualifies you for 1G pipe only. It’s the narrowest qualification because you never actually weld out of flat position.

2G: Horizontal Fixed Pipe

In 2G, the pipe axis is vertical (pipe stands upright), and the joint is horizontal. You weld around the pipe in a horizontal plane.

Setup

• Pipe is vertical, joint at a convenient working height
• You walk around the pipe (or the pipe is accessible from all sides)
• The weld axis is horizontal

Technique

• Similar to 2G plate: gravity pulls the puddle down
• Angle the electrode slightly upward to fight sag
• The challenge is maintaining a consistent bead profile as you work around the circumference
• Transitions around the pipe aren’t dramatic since you stay horizontal throughout

Key Challenge

Because the joint is horizontal on a curved surface, your approach angle changes continuously. At 12 o’clock you’re reaching up, at 3 and 9 o’clock you’re working straight in, and at 6 o’clock you’re reaching down. Keep your body position comfortable at each station.

Certification Scope

2G pipe qualifies you for 1G and 2G pipe positions.

5G: Horizontal Pipe, Fixed Position

In 5G, the pipe is horizontal and doesn’t rotate. You weld around it from one side, working from the bottom (6 o’clock) up to the top (12 o’clock) on both sides, or from top to bottom. This is the first truly positional pipe test.

Setup

• Pipe is horizontal, clamped or fixtured so it can’t move
• Typically welded from the bottom up on both sides (split technique)
• The weld axis is horizontal, but you weld through overhead, vertical, and flat positions

Technique: Uphill Method (Standard)

Start at the 6 o’clock position (bottom dead center) and work upward on one side to 12 o’clock. Then start at 6 o’clock again and work up the other side to meet the first bead at 12 o’clock.

Root pass: At 6 o’clock, you’re in overhead. Keep amperage lower and the arc tight. As you pass through 3 or 9 o’clock (vertical), use the shelf technique with a slight pause at the edges. At 12 o’clock (flat), you can push a bit more heat.

Fill and cap: Same progression. Each position transition needs amperage and speed adjustment. The transition zones (around 4-5 o’clock and 7-8 o’clock, where overhead becomes vertical) are where most defects occur.

Technique: Downhill Method

Start at 12 o’clock and work down. Faster but produces less penetration. Used for thin-wall pipe and non-critical applications. Some pipeline codes (API 1104) allow downhill for certain procedures.

Certification Scope

5G pipe qualifies you for 1G, 2G, and 5G pipe positions. It also qualifies for 1G, 2G, 3G, and 4G plate groove welds because the 5G test includes overhead, vertical, and horizontal welding.

6G: 45-Degree Fixed Pipe

The 6G position is the king of welding tests. The pipe is fixed at a 45-degree angle, which forces the welder through every position in the most challenging configuration possible.

Setup

• Pipe is clamped at 45 degrees from horizontal
• The joint is accessible from all sides, but the position changes constantly around the circumference
• Typical test coupon: 6-inch schedule 80 pipe with a standard V-groove

Position Transitions

As you weld around the pipe at 45 degrees, you hit:

• 6 o’clock area: Overhead combined with an uphill angle
• 3 o’clock area: A blend of horizontal and vertical
• 12 o’clock area: Flat combined with a downhill angle
• 9 o’clock area: Another horizontal/vertical blend

These aren’t clean transitions. The angle shifts constantly, and the puddle behavior changes every few degrees of travel. You can’t settle into any one technique for long.

Technique

Root pass: Start at 6 o’clock (overhead-uphill). Lowest amperage, tightest arc. Maintain the keyhole (TIG) or whip technique (E6010). As you come up to 3 o’clock, the position eases and you can add slightly more heat. At 12 o’clock, reduce speed to avoid a fat bead in the near-flat position.

Fill and cap: Run narrow stringers in the overhead-vertical section. As you transition to the flat-horizontal section at the top, widen the bead slightly to match the groove fill rate. The key is smooth transitions, not abrupt changes in technique.

Why 6G Is the Standard Test

A welder who passes a 6G test has demonstrated competence in every position on the most demanding joint configuration. It’s efficient: one test replaces four or five individual position tests.

Certification Scope

Test Pipe Specifications

Choosing the Right Certification Position

Which position you test on depends on what work you plan to do:

Shop fabrication (pipe spools, headers): 1G covers most production work since positioners rotate the pipe. Some shops require 2G or 5G for joints that can’t be rotated.

Structural field work: 5G or 6G. Field pipe is fixed in place and can’t be rotated. 5G is adequate for horizontal pipe runs. 6G covers everything.

Refinery and power plant work: 6G is the standard entry requirement. Most contractors won’t hire a pipe welder without a current 6G certification. The test is usually TIG root / stick fill on schedule 80 carbon steel.

Pipeline work: API 1104 governs pipeline welding. The test is typically 6G with E6010 downhill root and E8010 fill/cap, or mechanized welding procedures. Pipeline certification is separate from AWS or ASME qualification.

Boiler and pressure vessel work: ASME Section IX governs. 6G with a TIG root qualifies for the widest range of work. Most boiler codes also require specific supplementary tests (impact testing at low temperatures, for example).

Practice Progression

Build your pipe welding skills in this order:

1. 1G rolled pipe: Learn to control the puddle on a curved surface with consistent heat
2. 2G fixed: Add the horizontal welding challenge on the curved surface
3. 5G fixed: Now you’re welding through all plate positions on pipe. This is where the real learning happens.
4. 6G fixed: The final step. Adding the 45-degree angle forces continuous position transitions.

Don’t skip steps. A welder who can’t produce clean 5G welds isn’t ready for 6G. And a welder who struggles with 2G plate welding isn’t ready for 5G pipe.

Common Mistakes

Treating 5G like four separate plate positions. The transitions on pipe are continuous. You can’t stop at 3 o’clock and reset your technique for vertical. The adjustments happen in motion, gradually, as you move around the pipe.

Not adjusting amperage for position changes on 6G. Some welders set one amperage and try to make it work all the way around. That’s too hot at the top and too cold at the bottom. Use a foot pedal on TIG or adjust the machine at quadrant stops.

Ignoring start and stop locations. Where you start and end each bead on pipe affects the final quality. Stagger starts on subsequent passes so you don’t stack all the start/stop zones on top of each other. Offset by at least 1 inch between passes.

Poor tack welds on pipe. Tacks on pipe must be feathered or ground to blend into the bevel. A fat, unblended tack creates a bump that the root pass has to melt through, often producing lack-of-fusion.

For tips on passing the 6G test, see the 6G pipe welding test tips guide. For the multi-pass sequence on pipe, read root pass, hot pass, fill, and cap. For plate positions, see the 1G, 2G, 3G, 4G plate positions guide. Return to pipe welding or the welding techniques pillar for more.