AWS A2.4 weld symbol
Surfacing Weld Symbol
A surfacing weld symbol is two back-to-back arcs, calling for weld metal built up on a surface rather than in a joint — hardfacing, corrosion cladding or restoring a worn part.
How to read the surfacing weld symbol
- The symbol is always drawn on the arrow side of the reference line only. It may not be placed on the other side, because the arrow identifies the surface.
- The minimum thickness of the deposit is written to the left of the symbol.
- If the whole surface is not to be covered, the extent and location are shown on the drawing, not on the symbol.
- No size, length or pitch dimensions apply — only the build-up thickness.
- The tail commonly carries the surfacing alloy or process specification.
Where the dimensions go
| Position | What it specifies |
|---|---|
| Left of the symbol | Minimum height of the weld deposit |
| In the tail | Surfacing alloy, process or specification |
| On the drawing | Extent and location of the surfaced area |
Joint types
- Not a joint — applied to a surface
Practical notes
- Surfacing covers three distinct jobs: hardfacing for wear, cladding for corrosion, and build-up to restore worn dimensions.
- Because the symbol applies to a surface and not a joint, it never appears above the reference line.
- Dilution control matters: the first layer of a clad overlay picks up base metal, which is why a buffer layer of E309L or ER309L is often specified before the final alloy.
Surfacing Weld symbol — common questions
What does the surfacing weld symbol look like?
Two semicircular arcs drawn side by side below the reference line, on the arrow side only. It never appears above the reference line.
Why can the surfacing symbol only be on the arrow side?
Because the arrow identifies the surface to be built up. There is no far side of a surface, so the other-side placement has no meaning.
What does the number to the left of a surfacing symbol mean?
The minimum height of the build-up — how thick the deposited layer must be.
What is the difference between hardfacing and cladding?
Both use the surfacing symbol. Hardfacing deposits a wear-resistant alloy to fight abrasion or impact. Cladding deposits a corrosion-resistant alloy, commonly stainless or nickel, over a cheaper base metal.
Welding symbol anatomy
Every weld symbol attaches to the same framework. If any part of the diagram above is unfamiliar, the full guide to reading welding symbols walks through the whole system.
| Reference line | The horizontal backbone of every welding symbol. Everything else attaches to it, and it is always drawn horizontal on the drawing. |
|---|---|
| Arrow | The leader and arrowhead that connect the reference line to the joint. The side of the joint the arrow touches is the arrow side. |
| Weld symbol | The shape that says which kind of weld is required — triangle for a fillet, V for a V-groove, circle for a spot, and so on. |
| Arrow side (below the line) | A weld symbol drawn below the reference line calls for a weld on the side of the joint the arrow points to. This is the convention that catches people out most often. |
| Other side (above the line) | A weld symbol drawn above the reference line calls for a weld on the far side of the joint. |
| Both sides | Symbols drawn above and below the reference line call for welds on both sides of the joint. |
| Tail | An optional fork at the far end of the reference line, used to reference a specification, process or procedure such as GMAW or a WPS number. |
| Dimensions | Size is placed to the left of the weld symbol; length and pitch are placed to the right. |