Square Groove Weld Symbol
The square groove weld symbol is two short parallel lines standing on the reference line. It calls for a butt weld between square-cut edges with no bevel. Below the line means arrow side, above means other side, both sides means weld from both sides; the root opening goes between the lines and the groove weld size in parentheses on the left.
How to read the square groove weld symbol
A square groove joint is two plates butted edge to edge with square-cut edges, sometimes with a small gap. The two parallel lines of the symbol show those two square edges.
Below the reference line, weld from the arrow side; above, from the other side. On both sides, weld from both sides, which is how thicker square butts get full penetration.
What each dimension position means
| Position | Meaning |
|---|---|
| Left, in parentheses (E) | Groove weld size: the depth the weld is required to reach. No size on a single-sided square groove usually means complete joint penetration. |
| Between the lines (R) | Root opening: the gap between the plate edges before welding. |
| Right (L) | Length of weld, when it is not the full joint. |
| Tail | Process, WPS or other reference. |
Example callout, read aloud
“Make a square groove weld from the arrow side with a 1/16-inch root opening, reaching a groove weld size of 1/8 inch, using gas tungsten arc welding.”
Example: reading the callout piece by piece
- Two parallel lines below the line: square groove, arrow side.
- 1/16 between the lines: set the plates 1/16 inch apart.
- (1/8) on the left: the weld must reach 1/8 inch into the joint.
- GTAW in the tail: gas tungsten arc welding.
Result: Make a square groove weld from the arrow side with a 1/16-inch root opening, reaching a groove weld size of 1/8 inch, using gas tungsten arc welding.
When it is used
- Butt joints in thin sheet and plate, where the arc can penetrate without bevelling the edges.
- Two-sided welds on moderate thicknesses, welding from each side to meet in the middle.
- Laser, electron beam and submerged arc welds that penetrate deeply without a groove.
Common mistakes
- Putting the root opening to the left. Root opening goes between the lines. The left is for groove weld size.
- Assuming full penetration on a two-sided weld with sizes given. Sizes on each side tell you the depth from that side. Add them to see if they meet.
- Leaving no gap on thicker plate. Follow the root opening shown; without it the root may not fuse.
- Ignoring the tail reference. The WPS in the tail sets the process and parameters that make the specified penetration achievable.
Related weld symbols
- V-groove weld: A V-groove bevels both edges when the plate is too thick for a square butt.
- Back and backing weld: A back weld on the other side helps a square butt reach full penetration.
- Bevel groove weld: A bevel prepares only one edge.
- Edge weld: Edge welds join parallel sheet edges rather than a butt.
- U-groove weld: U-grooves suit thick plate with less filler than a V.
Every weld symbol page: welding symbols chart
Calculators and further reading
Frequently asked questions
What does a square groove weld symbol look like?
Two short parallel lines standing at right angles on the reference line.
What does the number between the lines mean?
The root opening, the gap between the plate edges before welding.
What does the number in parentheses mean?
The groove weld size, the depth of fusion required.
What if the symbol is on both sides of the line?
Weld from both sides of the joint. Each side may have its own groove weld size.
Sources
- AWS A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination, American Welding Society
COPLAIN AI PLATFORM
Generate yours automatically from your existing docs
Coplain turns butt-joint weld symbols into clear fit-up and welding steps, with root opening and penetration checks built in.
Generate yours automatically with Coplain →Related Tools & Templates