Basic welding symbology divides the welds into:
- Groove welds.
- "Fillet" welds.
- Plug welds.
- Slot welds.
In general, the symbols are similar to the weld setup to be performed.
These weld symbols can be the same or different in a joint with two types of weld.
They can be above the arrow (welding on the opposite side of the arrow) or below (welding on the same side of the arrow).
The most commonly used welding symbols are shown in the picture below:
(1): Groove welds.
(2): Other types: "Fillet" welds (Welds in angle), plug welds, slot welds.
"Fillet" weld symbols, groove welds in half V, K, J are always indicated with a leg perpendicular to the left of the symbol. Same goes to other less common welding symbols.
The picture below presents a summary of the basic welding symbols:
Angle welds (or "Fillet" welds)
"Fillet" welds are used in “T” joints but may also be used in overlapping or edge joints (see examples below with the darkened weld).
As its symbol suggests, a angle weld is a weld whose cross section is approximately triangular.
Important information regarding positioning and sizing:
- The perpendicular side of the symbol is always to the left, regardless of the weld orientation.
- The dimension (size) of the weld must be written on the left side of the symbol.
- If both sides (of the same weld) have the same size, only one dimension must be informed.
- Even though it is uncommon, uneven "fillet" welds may still be used. In these cases, the dimensions of the two legs must be informed and the symbol will indicate which of the sides is the largest.
- The length of the weld is given on the right side of the symbol. If the length is not informed, the weld must extend until there is an abrupt change in the welding direction, as occurs at the end of a plate (indicated in the following picture):
- The dimensions of a tack weld are indicated to the right of the symbol, the length of the weld is indicated first, then the spacing. One must not forget the “trace” between these two dimensions. Also note that the spacing refers to the distance between the centers of the welds.
Groove welds are commonly used in butt joints, or end to end joints (See examples in the picture below).
However, they are also used in angle joints, which is a reason for great confusion and misunderstanding among professionals.
Yes, an angle joint can have a groove weld.
When the weld is deposited on a beveled surface, penetrating and melting the base metal, we say that it is a groove weld.
I'll cover examples of groove weld in angle joints in another article
Plug and Slot welds
These welds are used to join overlapping parts where one of them has holes, whether round (plug weld) or elongated (slot weld).
The filler metal is deposited in these holes where it penetrates and fuses the base metal, forming the weld.
A weld is performed with the purpose of creating a "backing" weld.
The most common use of it is to indicate that welding should be done on one side and gouging on the other. The weld is complete when the gouged side is also welded.
This symbol is used to indicate that the surface in question requires a weld overlay. This coating can be used for protection against corrosion (“clad”) or against wear.
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