Supplementary Welding Symbols 👨‍🏭 2022

Supplementary symbols are those that detail, explain or provide more detailed information about the type of work to be done. Sometimes they may give details about the weld bead.

They are usually represented on the reference line closer to the arrow.

The picture below shows the supplementary welding symbols.

1 - Weld all around

The first symbol (open circle) is used when we want to indicate welding around the entire contour, see example below.

2 - Field weld

A detail for the flag symbol is that its presence indicates that the welding must be done “in the field” or at the installation of the equipment.

The absence of this flag indicates that welding must be carried out at the factory.

3 - Melt through

The symbol is applicable to a weld made on one side only and indicates full penetration.

When root reinforcement is critical, this should be indicated on the left side of the symbol, please look at the example given below.

4 - Consumable insert

This symbol must be accompanied with details about the type of consumable, with a note on the drawing or even using the tail space.

5.1 - "Backing"

When backing is required to achieve full penetration, the rectangle symbol is used.

If the backing is required to be removed after welding, an “R” must be inserted inside this rectangle.

Note that the backing symbol and the plug weld symbol are the same. But the context will make it clear what are symbol's intention.

5.2 - Spacer

The spacer name and picture are usually self-explanatory (see it below).

In the example below, a 12 X 6 mm spacer made of low carbon steel type (SAE 1020) is used:

Contour (6, 7 and 8)

A flush symbol means that the weld reinforcement must be removed.

The weld should be flush or level with the base metal.

This is a recognized and established method to increase fatigue resistance, but it is also used to facilitate access to non-destructive tests such as ultrasound examination.

It is understood that this AWS symbol (contour) refers to the condition “as welded”, ie without any further mechanical treatment.

I have never seen this symbol used. And besides not seeing any sense in it, I believe that this practice is detrimental to quality.

For example, when convexity symbol is required, a welder may be encouraged to fill more to make the weld more convex.

Examples of the use of other profile symbols:

Finish symbols

There are also finishing symbols, which indicate the method of finishing the weld surface. These symbols are:

  • C - Chipping
  • G - Grinding
  • M - Machining
  • R - Rolling
  • H - Hammering
  • U - Unspecified

Acronyms/letters refer to the first letter of English terms.

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Would you like to learn about welding? Check my Quick Welding Course.


When you need to include a fact or piece of information in an assignment or essay you should also include where and how you found that piece of information (Welding Symbols).

That gives credibility to your paper and it is sometimes required in higher education.

To make your life (and citation) easier just copy and paste the information below into your assignment or essay:

Luz, Gelson. Supplementary Welding Symbols. Materials Blog. dd mmmm. yyyy. URL.

Now replace dd, mmmm and yyyy with the day, month, and year you browsed this page. Also replace URL for the actual url of this page. This citation format is based on MLA.


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Materials: Supplementary Welding Symbols 👨‍🏭 2022
Supplementary Welding Symbols 👨‍🏭 2022
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