Weld symbol
Surfacing weld symbol
Two scalloped bumps on the reference line call for weld metal deposited onto a surface rather than into a joint. The size to the left is the thickness of the deposit, not a joint dimension.
Reads asArrow side: surfacing weld, 1/8 size.
How to read it
A surfacing weld is not a joint at all. It is weld metal laid down on an existing surface to build it up, restore lost material, or clad it with an alloy that resists wear or corrosion. The symbol reflects that: two rounded bumps sitting on the reference line, suggesting overlapping beads on a face rather than any joint cross section.
Because there is no joint, there is no other side. The symbol always sits on the arrow side, and the arrow points at the surface being built up. The number to the left is the minimum thickness of the deposit measured from the original surface outward, which is the one dimension the process is controlled by.
The extent of the surfacing has to come from the drawing. A surfacing callout on its own says how thick to build up but not how far to spread; that area is normally shown by hatching, by dimensioned boundaries, or by a note. Where the whole face is to be covered, the drawing usually says so explicitly rather than leaving it to the symbol.
The tail carries a lot of weight on surfacing callouts because the deposited alloy matters more than the geometry. Hardfacing a bucket lip, building up a worn shaft, and cladding a vessel interior are three completely different jobs that produce the same symbol, and it is the tail or a note that tells you which consumable and procedure applies.
Where each dimension goes
- Deposit thickness (left of the symbol)
- Minimum height of the surfacing measured from the original surface outward.
- Arrow side only
- Surfacing has no other side because there is no joint. The arrow points at the surface being built up.
- Area of coverage
- Shown by hatching, boundary dimensions, or a note on the drawing rather than by the symbol.
- Tail
- Names the consumable, process, or procedure, which on surfacing work usually matters more than the geometry.
Worked examples
Each one is a drawing, the sentence it comes out as, and then the mark-by-mark account of why. Read the sheet first and say the sentence yourself before you look down.
Example 1: Hardfacing a wear surface
TitleHardfacing a wear surfaceRefSurfacing weldEx1 / 2Reads as
Build the arrow-side face up 3/16 thick with hardfacing deposit.
Which mark says so
- surfacing symbolBelow the reference lineA surfacing weld on the arrow side of the joint
- 3/16Left of the symbolThickness of the deposit
- Hardfacing per procedureIn the tailA reference the drawing carries - a process, procedure or specification
The 3/16 to the left of the scalloped symbol is the minimum deposit thickness above the original surface, and the tail names the consumable that has to be used.
And what it does not say
- No length is given, so each weld runs the full length of the joint.
- Nothing sits above the reference line, so the far face of the joint stays bare.
- There is no circle at the elbow, so the weld does not continue around the joint.
Example 2: Build-up before machining
TitleBuild-up before machiningRefSurfacing weldEx2 / 2Reads as
Deposit 1/4 of surfacing on the worn journal, then machine it back to size.
Which mark says so
- surfacing symbolBelow the reference lineA surfacing weld on the arrow side of the joint
- 1/4Left of the symbolThickness of the deposit
- Machine after weldingIn the tailA reference the drawing carries - a process, procedure or specification
The size gives the minimum deposit and the tail notes the subsequent machining, so the welder knows to leave enough stock above the finished diameter to clean up.
And what it does not say
- No length is given, so each weld runs the full length of the joint.
- Nothing sits above the reference line, so the far face of the joint stays bare.
- There is no circle at the elbow, so the weld does not continue around the joint.
Common mistakes
- Reading the size to the left as a joint dimension rather than as deposit thickness above the surface.
- Placing a surfacing symbol above the reference line, which has no meaning because there is no joint.
- Guessing the area to be covered when the drawing defines it separately.
- Ignoring the tail, which on surfacing work usually carries the consumable requirement.