Weld joint types and positions: 1G, 2F and more

Five joint types

Every weldment joins parts in one of five basic ways:

Don't confuse the joint with the weld. The joint is the geometry before welding. The weld is what you deposit in it. A T-joint can take a fillet weld or a groove weld, and the symbol on the drawing tells you which.

Parts of a groove

Groove preparation has its own vocabulary, and exam questions use the words precisely:

• Root opening: the gap between the pieces at the root.
• Root face: the flat land left at the bottom of the prepared edge.
• Bevel angle: the angle of the cut on one piece, measured from a line square to that piece's surface. On a plate lying flat, that line is vertical.
• Groove angle: the total angle between the two prepared faces.
• Backing: material behind the root that supports the first pass and may stay or be removed.

Shapes include square, V, single bevel, U and J. Know what each looks like and why a thicker plate needs more preparation: the weld has to reach the full thickness, and the shape decides how much metal and heat that takes.

Position codes: the number and the letter

A position code has two parts. The number tells you the position, and the letter tells you the weld type: G for groove, F for fillet.

So 1G is a groove weld in the flat position, 2F is a fillet weld in the horizontal position and 4G is a groove weld overhead. Positions 2, 3 and 4 are out of position: gravity pulls the molten pool away from the joint, so they take more control than flat.

Pipe positions

Pipe adds codes because the pipe can be turned or fixed:

• 1G: pipe axis horizontal and rolled while the welder stays on top, so the weld is always made in the flat position.
• 2G: pipe axis vertical and fixed, with the weld running around it horizontally.
• 5G: pipe axis horizontal and fixed. The welder works around the pipe, so the weld passes through flat, vertical and overhead.
• 6G: pipe fixed at an incline of 45 degrees. One weld passes through flat, horizontal, vertical and overhead at an incline, which is why it's a common all-position qualification test.

A welder qualified in one position is often also qualified for certain other positions under the code's rules. The exact coverage depends on the code and the test, so read yours.

To practice the codes against drawings, the free weld position trainer shows plate and pipe joints, from 1G to 6G and 1F to 4F, and asks you to name the position or pick the drawing for a code.

Why positions matter to an inspector

Position affects the weld in three ways a CWI needs to understand:

1. Technique and settings. The WPS can limit current or travel speed by position, since a molten pool in the vertical or overhead position is harder to control.
2. Likely flaws. Overhead and vertical work can show sagging, undercut and lack of fusion if technique slips.
3. Qualification. A welder's record covers certain positions. Checking that the welder's record matches the position of the weld is part of verification. For how the records relate, see WPS, PQR and WPQ explained.

A simple memory trick: flat is 1, horizontal is 2, vertical is 3 and overhead is 4. Say the code aloud as a phrase, "two-F, horizontal fillet", until the two halves arrive together.

Joints and positions on a drawing

The symbol tells you the weld type, the side and the size. The joint and position come from the drawing's views and notes. Read the symbol first, then confirm the joint shape it implies. If you want practice, the welding symbol builder lets you pick a weld, side and dimensions and see where each element sits, and how to read welding symbols walks through the method step by step.

Check where you stand

Part A is closed book, so the codes and vocabulary have to be in your head. Try this: draw the five joints from memory, label the parts of a V-groove, then say what 3G, 4F and 6G mean without looking. If anything stalled you, you've found a topic to fix. The free 10-question Part A check is scored by area and shows exactly which topics to study first. Take it here, then read the full Part A guide for how the exam is weighted.

FAQ

What does 1G mean in welding?

It's a groove weld in the flat position. The 1 is the position, flat, and the G is the weld type, groove.

What is the difference between 2G and 2F?

Both are horizontal positions. 2G is a groove weld and 2F is a fillet weld. The letter tells you the weld type.

Which position is hardest?

There's no single ranking. Horizontal, vertical and overhead are all out of position, where gravity works against the molten pool. On pipe, 6G is a common all-position qualification test because one weld passes through flat, horizontal, vertical and overhead at an incline.

Are position codes the same in every code?

The basic number and letter system is widely shared, but each code sets its own qualification ranges and test rules. Always use the code in front of you.