Fillet Gauge
My courseAsk Tack AIFree practice checksCWI Part ACWI Part BCWI Part C D1.1CoursesGuidesCWI Part A practice test: 165 questions, closed book, 10 domainsCWI Part B practice test: replicas, tool kit and a timed planCWI Part C practice test and D1.1 exam guideAll guidesAll toolsAboutContact

Surfacing weld symbol: what it means on a drawing

Fillet Gauge editorial teamSources checked 3 min read

The surfacing weld symbol is two small arcs side by side, hanging below the reference line. It calls for weld metal laid onto a surface rather than joining two parts: building up a worn shaft or hardfacing a wear plate. It is drawn on the arrow side only, because the arrow points at the surface to build up.

A plate drawn end on with a layer of weld beads built up across part of its top surface, beside a surfacing symbol below the reference line with 1/8 on its left
Arrow side only. The number on the left is the buildup thickness. Numbers are invented.
Use this diagram

How to read it

  1. Check the arrow. The arrow touches the surface that gets the weld metal. There is no other side to read, so a surfacing mark above the line is a drafting error to ask about.
  2. Read the left side. The number is the thickness of the built-up layer, measured from the original surface. 1/8 means build the surface up 1/8.
  3. Read the right side. A number there is a length of surfacing. With no length and nothing else on the drawing, the surfacing runs the full length of the surface.
  4. Find the area. The symbol can't show a width or a shape, so the drawing gives the area with dimensions, hatching or a detail. Read that before you start, or you'll surface the wrong patch.
  5. Look for layers. When different layers need different thicknesses or materials, the drawing can use more than one reference line, read from the arrow outward, or a note.

Try one question

Question 1 of the free 10-question check on CWI Part A. No signup. Then ask Tack, the AI study buddy, why the answer is right and the others are wrong.

Question 1 of 10 · free checkUntimed

Symbols - Welding and NDE

On a welding symbol, what does a circle at the junction of the arrow and the reference line indicate?

Press A–D or 1–4 to choose an answer while this question is on screen.

Choose an answer to begin

Direction on round parts

On a flat plate, surfacing may run along the length or across it. On a shaft or other round part, the beads run either along the axis or around the circumference. The direction changes how the part heats and distorts, so a drawing that cares will say which in a note or the tail. If it doesn't, ask rather than guess.

Ask Tack before you buy AI your Fillet Gauge study buddy

See what's on the CWI Part A exam, test yourself with 5 quick questions, or find the plan that fits you.

The CWI Part A course

Available now · instant access

Learn every Part A topic, then prove it on timed practice exams.

  • 10modules of lessonsEvery task on the outline
  • 2full-length timed exams165 questions in 135 minutes each
  • 704practice questionsEach one explained
  • 5worked calculationsStep by step
  • 1week-by-week study planSet to your exam date

Turn a practice answer into a study step. In untimed practice, ask Tack AI about any question you answer, follow up, then see your weakest topics and what to drill next.

Part A course$99Get the Part A course · $99

Instant access. Terms and refunds · Secure checkout by Stripe · Billed by Nori Software

Compare plans

Every answer comes with a full explanation.

Common mix-ups

  • Surfacing or back weld. A back or backing weld is one open half-circle, opposite a groove symbol. Surfacing is two arcs side by side with no groove symbol, because nothing is being joined.
  • Surfacing or seam weld. The seam mark is a circle with two lines through it. Surfacing is two open arcs.
  • Thickness or contour. The number on the left is buildup thickness. If the surface must finish flat or at a set dimension after grinding or machining, that comes from a contour mark with a finish letter, or from a dimension on the drawing.

Surfacing on the CWI exam

Surfacing is one of the basic weld symbols in Symbols, Welding and NDE, at least 10% of CWI Part A, which is closed book. The arrow-side-only rule is a simple point, and simple points are the ones that cost marks when they're missed. On Part B, Utilization of Specifications and Drawings is at least 8% of the practical.

Practice it

The welding symbols quiz includes the surfacing mark and its arrow-side rule, with an explanation for every answer. See it with every other basic shape on the welding symbols chart.

Built up your symbols? Check the rest of Part A

Take the free 10-question check. It's weighted to the Part A outline, scored by domain and needs no signup, so you see whether symbols or another domain costs you the most points. The Part A course gives you a lesson on reading welding and NDE symbols and on every other exam subject, two full-length timed practice exams, and a worked explanation with every answer.

Sources

Show the list

Facts checked 24 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.

Your next step

Ready to see where you stand on CWI Part A?

Free, untimed and scored by domain. No signup.

Start the free 10-question check

Part A course. Lessons, timed practice exams and a plan around your exam date. Get Part A course · $99 See the plans or read the free sample lesson.Terms and refunds

Want a timed run? Try the free 25-question mini-mock. The first 5 need no email.

Free tools for this topic

Free toolWelding symbol builder: draw a symbol and read it

Prefer paper? Free printables

From the blog

Requirements, fees and payFillet weld symbol: what it means on a drawingRequirements, fees and payWeld all around symbol: what it means on a drawingRequirements, fees and payField weld symbol: what it means on a drawingRequirements, fees and payStitch weld symbol: what it means on a drawingRequirements, fees and payV-groove weld symbol: what it means on a drawingRequirements, fees and payBevel groove weld symbol: what it means on a drawingRequirements, fees and payPlug and slot weld symbol: what it means on a drawingRequirements, fees and paySpot weld symbol: what it means on a drawingRequirements, fees and payBack weld and backing weld symbol: what it means on a drawingRequirements, fees and payWeld contour symbol: what it means on a drawingRequirements, fees and paySquare groove weld symbol: what it means on a drawingRequirements, fees and payU-groove weld symbol: what it means on a drawingRequirements, fees and payJ-groove weld symbol: what it means on a drawingRequirements, fees and payFlare-V groove weld symbol: what it means on a drawingRequirements, fees and payFlare-bevel groove weld symbol: what it means on a drawingRequirements, fees and payEdge weld symbol: what it means on a drawingRequirements, fees and paySeam weld symbol: what it means on a drawingRequirements, fees and payMelt-through symbol: what it means on a drawingRequirements, fees and payDouble-V groove weld symbol: what it means on a drawing