Welding Position and Joint Type Designations
A joint type describes how the parts meet. A weld type describes the weld joining them. A position describes its orientation during welding. In familiar US test designations, G means groove weld and F means fillet weld; the number identifies the test position. Read the product form, rotation and progression alongside that code.
What does each designation tell you?
Imagine two plates forming a bracket. “T-joint” tells you how the plates meet. “Fillet weld” identifies the weld cross-section. “Horizontal” describes how the weld sits during welding. The drawing symbol adds the required size, side and extent. Each term answers a different question.
- Joint type
- The arrangement of the members: butt, T, lap, corner or edge.
- Weld type
- The weld being made, such as a groove or fillet weld. A joint arrangement can allow more than one weld type.
- Welding position
- The weld’s orientation relative to the horizontal plane, including the slope of its axis and the rotation of its face.
- Welding symbol
- The drawing instruction identifying the weld and its requirements. Its position on the page does not establish how the assembly is held in the shop.
For the full drawing convention, use the welding-symbol reading guide.
AWS distinguishes test designations such as 1G–4G from production positions described as flat, horizontal, vertical or overhead. Shops often use the number-letter labels as shorthand, but a job record should also state the actual orientation. AWS explains this distinction.
The five basic welding joint types
Start with the members before considering the weld. These cross-section sketches show the basic arrangements. They leave out bevels, root gaps and weld size so the joint geometry remains clear.
Members meet edge to edge, approximately in the same plane.
An edge of one member meets the face of another, forming a T.
One member overlaps the other.
The members meet at their edges to form a corner.
Adjacent edges of parallel or nearly parallel members meet.
A joint name does not establish its load capacity. Thickness, material, weld dimensions, penetration, loading and the design requirements still matter. A T-joint can be designed with fillet welds or with groove welds in prepared edges; the drawing determines which detail to make.
The AWS joint-type reference lists all five arrangements. Its weld-examination guide also identifies groove-welded T-joints and fillet-welded lap joints. For a closer comparison, see corner joints and T-joints.
What do G and F mean?
In the position designations used here, G identifies a groove-weld test and F a fillet-weld test. Neither letter identifies a material, welding process or strength grade.
G: groove weld
Weld metal is deposited in a groove between workpieces. The preparation can be square, V, bevel, U, J or another specified shape. A square groove does not need a bevel.
G does not mean full penetration. The design may specify complete joint penetration (CJP) or partial joint penetration (PJP). Those requirements come from the joint detail and specification.
F: fillet weld
A fillet has an approximately triangular cross-section and joins intersecting surfaces. It is common on T-, lap and corner joints. The required leg size or throat, length and side must still be stated.
F does not mean T-joint. Changing the member arrangement can keep the fillet weld family, while changing the preparation can put a groove weld into a T-joint.
Orange represents weld metal in these schematic sections. The sketches do not specify production dimensions. See Miller’s groove and fillet overview for common structural applications.
The same T-joint can have different welding positions
Rotate the assembly and its joint type stays the same. Its position relative to gravity changes. This distinction explains why a joint drawing alone may not tell you the position used in production.
What changes: pool support, access and the actual working position.
What stays: the T arrangement and the illustrated fillet-weld type.
This is a geometric example, not a fixture or welding procedure. The arrow points downward in both views. The weld axis runs into the page in both sketches; rotating the cross-section does not turn this into a vertical seam.
How to read 1G–4G and 1F–4F on plate
The number selects the familiar test-position family, while G or F distinguishes the weld. Weld axis means the line along the weld; weld face means its exposed surface. A seam can have a horizontal axis while its face is vertical.
On smaller screens, scroll the tables sideways. You can also focus a table and use the arrow keys.
| Position | Groove-weld plate test | Fillet test | Detail to keep clear |
|---|---|---|---|
| Flat | 1G: weld from above; face approximately horizontal. | 1F | Arrange the fillet face upward; a T standing on a flat base is usually the 2F illustration. |
| Horizontal | 2G: weld axis horizontal; plate face vertical. | 2F | Groove and fillet coupons have different cross-sections. |
| Vertical | 3G: weld axis vertical. | 3F | State whether welding progresses upward or downward. |
| Overhead | 4G: weld from underneath the joint. | 4F | “Overhead” describes the weld orientation, not simply the height of the workbench. |
Vertical-up and vertical-down describe travel direction. The number 3 alone does not select it. The process, consumable and approved procedure must permit the intended progression.
Position affects how the liquid pool is supported and how the operator reaches the joint. It does not supply current, voltage, travel speed or an acceptance criterion. Detailed positional technique is covered in the 1G–6G welding-position guide.
Orientation references: AWS test/production terminology and ELGA’s position chart. Exact angular limits belong to the adopted standard.
For pipe, read the axis and whether it rotates
For circumferential groove welds, 1G and 2G also have pipe test configurations. Fixed pipe adds 5G and 6G. The sketches show the pipe axis and circumferential joint; they do not show an electrode angle or an access restriction.
The welding point can remain near the top while the pipe turns.
The groove runs horizontally around the upright pipe.
Travel around the joint passes through top, side and bottom regions.
Inclination adds changing local orientation and access around the joint.
In 2G pipe, the pipe axis is vertical but the circumferential weld is horizontal. In 5G, the pipe axis is horizontal and the weld passes through changing local orientations. These two axes are the reason descriptions such as “horizontal pipe weld” are incomplete.
For example, a pipe butt joint may be welded with rotation during shop fabrication and remain fixed during installation. The butt-joint geometry and groove-weld family can stay the same while the working positions change.
Schematic orientation comparison based on the manufacturer position chart. Rotation must be permitted by the procedure and production setup.
How do US labels compare with ISO 6947?
ISO 6947:2019 defines positions for testing and production. The comparison below identifies similar geometry; it does not establish an equivalent qualification. Butt-weld terminology in the ISO context also differs from the US groove-weld terminology used above.
| Working orientation | Common US test label | ISO designation |
|---|---|---|
| Flat | 1G groove / 1F fillet | PA |
| Horizontal butt/groove | 2G | PC |
| Horizontal-vertical fillet | 2F | PB |
| Vertical plate, upward / downward | 3G or 3F, with progression stated | PF upward / PG downward |
| Overhead butt/groove | 4G | PE |
| Horizontal-overhead fillet | 4F | PD in the common fillet test arrangement |
| Fixed horizontal-axis pipe, upward / downward | 5G, with progression stated | PH upward / PJ downward |
| Fixed pipe inclined at 45°, upward | 6G with upward progression | PH-L045 in ISO 6947:2019 |
| Fixed pipe inclined at 45°, downward | 6G with downward progression | PJ-L045 in ISO 6947:2019 |
These earlier designations remain common in charts and documents. ISO 6947:2019 uses PH-L045 and PJ-L045 in its inclined-pipe examples; Sweden’s welding commission explicitly notes the change. Identify the edition and qualification scheme behind an existing record before interpreting it. The spelling change alone does not decide whether a qualification remains valid. Read the notation update.
PH and PJ describe upward and downward pipe welding; PF and PG describe the corresponding vertical positions. ISO also includes PK for orbital pipe welding. This is a practical comparison of the common designations, not a complete list of permitted test configurations or production-angle ranges.
Sources: ISO 6947 scope and designation examples, ELGA’s orientation chart and Svetskommissionen’s edition clarification.
What must you check beyond the position code?
A welding procedure and a welder’s qualification answer different questions. The welding procedure specification (WPS) describes how to make the weld. The supporting qualification record, or another route explicitly allowed by the code, establishes its basis. The welder’s performance record documents the individual’s demonstrated ability and the permitted range.
Do not assume every WPS has the same approval route. For example, TWI explains that AWS D1.1 allows prequalified procedures within specified limits. This is different from saying a position label qualifies a procedure. See TWI’s procedure explanation.
A useful record-reading example: “6G” is one field
ASME’s published QW-484A form separates Actual Values from Range Qualified. It also provides fields for process, backing, pipe diameter, deposited thickness for each process, position and vertical progression.
When reviewing a record marked “6G,” compare those fields with the intended job. The nickname cannot tell you whether a different process, diameter, thickness or progression is covered. This is an example of reading the form, not a completed test or a qualification ruling. View the original ASME form.
- Identify the drawing and governing standard. Record the edition, joint detail, required weld type, size, side and extent.
- Describe the actual production orientation. Include plate or pipe, pipe-axis direction, whether rotation is allowed and vertical progression where relevant.
- Match the procedure and personnel records. Confirm the process and applicable ranges, along with required continuity or validity records under the chosen scheme.
- Check access and verification. Confirm that the torch, filler and inspection method can reach the joint. Resolve a mismatch in the documents before adapting the setup.
For a laser-welding trial, add the actual material, thickness, joint preparation, fit-up and access constraints. A position designation can describe orientation; it cannot establish a laser parameter set or prove the resulting weld meets the drawing.
Share the material, thickness, joint detail, working orientation and acceptance requirements with Oceanplayer Laser. Include whether the part can be repositioned and where access is restricted.
Technical references
- AWS Inspection Trends: The Answer Is. Distinguishes alphanumeric test positions from production positions.
- AWS Welding Joints reference. The five basic joint arrangements and applicable weld types.
- AWS B1.10M/B1.10:2016 public preview. Its figure list identifies groove and fillet welds used in different joint types.
- Miller: Fillet and Groove Welds in Structural Steel Field Welding. Common weld families and groove preparations.
- ELGA Welding Consumables handbook, 2026, page 175. Visual orientation comparison; the inclined-pipe labels retain the earlier H-L045/J-L045 notation.
- ISO 6947:2019. Official scope. The text hosted by SSAB includes the main-position figures and Clause 5 designation examples.
- Svetskommissionen: Svetslägen. Welding-position terminology and the 2019 inclined-pipe notation change; in Swedish.
- TWI: Welding Procedure. The purpose of a WPS, supporting records and code-dependent approval routes.
- ASME Form QW-484A. Public suggested format for welder performance qualification, showing test values and qualified ranges.