WELD SYMBOLS ON DRAWINGS: A PRACTICAL REFERENCE GUIDE

If you are doing fabrication, sooner or later you will get handed a drawing with a bunch of triangles, circles, and letters on an arrow. That is the weld symbol language. Once you know it, you can build faster, quote cleaner, and avoid rework. If you do not know it, you end up guessing, and guessing gets expensive.

This guide focuses on the common symbols you will actually see on small to mid-size jobs around Edmonton: stairs, handrails, brackets, gates, trailer repairs, and general steel fabrication. Always follow the project specs if they exist, but these basics will cover a lot.

The three main parts: arrow, reference line, tail

• Arrow: points to the joint being welded.
• Reference line: the main horizontal line where the weld symbol sits.
• Tail: optional. Often lists the process or notes (like MIG, TIG, or special instructions).

Above or below the line matters

One of the biggest confusion points is placement:

• Symbol below the reference line: weld on the arrow side.
• Symbol above the reference line: weld on the other side.
• Symbols on both sides: weld both sides.

On a handrail base plate or a bracket, that can change everything. If the weld is only needed on one side for access or appearance, the drawing will usually show it this way.

Common weld symbols you will see

Fillet weld (triangle)

The triangle is the classic fillet weld. It is used for T-joints, lap joints, and corners. You will often see a size next to it, like 6 mm. That is the leg size unless the drawing notes say otherwise.

Groove welds (butt joints)

Groove weld symbols cover bevels and preps. The most common ones in general fabrication are:

• Single bevel: one side beveled.
• V-groove: both sides beveled.
• Square groove: no bevel, common on thinner material.

Groove symbols often come with extra details like bevel angle, root opening, or depth of prep. If you are unsure, do not guess. Ask before you cut the joint.

Size, length, and pitch: what the numbers mean

Weld symbols use numbers in predictable spots. Here is a simple way to read most of them:

Intermittent welds are common on lighter frames or non-critical components where full weld is not needed. Do not turn intermittent into continuous without approval. Over-welding can warp parts and create fit-up problems.

All-around and field weld symbols

• All-around: a small circle at the junction of the arrow and reference line. It means weld all the way around the joint.
• Field weld: a little flag at the junction. It means the weld is done on-site, not in the shop.

Field welds matter for mobile welding. If a drawing calls for a field weld, it is usually because the part cannot be fully welded before installation.

Contour and finish marks

Sometimes the symbol includes contour and finish instructions:

• Flat, convex, concave: contour of the weld surface.
• Grinding or machining letters: indicates how the finish is achieved.

This comes up on visible handrails, stainless work, or parts that need to sit flush. If a weld needs to be ground smooth, it should be shown or noted, because grinding takes time and changes the bead profile.

Shop reality: drawings are not always perfect

In the real world, you will see drawings with missing sizes, unclear arrows, or symbols that do not match the joint. When that happens, the correct move is to clarify before welding. A two-minute call can save a full rework day.

Need fabrication or mobile welding in Edmonton?

If you have drawings for a bracket, stairs, railings, or a custom steel project, YEGWELD can build and repair across Edmonton and nearby communities. We work from sketches, photos, or proper drawings, and we can help make sure the weld requirements match the actual use.

Call: 780-233-8285 or send us your drawings here.

This article is for informational purposes only and may contain inaccuracies. Always consult a certified welding professional before starting any project.