Welding is a fairly common and popular manufacturing process used to join to metals. Though welding is widely used, most of us are not very well-versed with the graphical representation of this process. Drawings that contain symbols and signs convey information and details about the type and size of weld. Hence, understanding these symbols and drawings is essential, because incorrect interpretation can lead to incorrect welding, which may affect the end product, and in many cases, ruin the product itself.
Welding being such a wide field, it is difficult to cover all the symbols that are used in welding drawings. We have covered the basic symbols in this Buzzle article. We have divided the symbols into four major sections for quick reference; elements of welding symbols, types of weld, supplementary symbols, complementary symbols, and dimensioning symbols.
Elements of a Welding SymbolReference Line:
It is placed near the joint it describes.Arrow:
It points to the location or joint or spot that is to be welded.Weld Symbol:
Distinguishes sides of the joint by using arrow and spaces above and below the reference line. The side where arrow points is known as arrow side while the opposite side is known as other side.Tail:
It indicates the welding or cutting process along with welding specification, procedures, or supplementary information related to the weld.L:
It indicates length of weld.P (Pitch symbol):
It is the distance between two consecutive welds, measured from the center of both welds.F (Finish symbol):
It indicates the need for finishing processes like grinding, brushing, or machining.Contour:
It indicates the shape of the finished weld bead.A (Groove angle):
It mentions the angle of the opening between the two welded parts.R (Root Opening):
It denotes the distance between the root edges of two metals that need to be joint. E (Groove Weld Size):
It indicates the size of the groove weld.S (Depth):
It indicates the size or penetration (strength) of certain type of welds.N:
It indicates the number of spots, seams, studs, plugs, slots, or projection welds.
Types of WeldSquare Butt Weld:
Butt weld joins two workpieces that lie in the same plane. Square butt weld joins two pieces that are flat and parallel to each other.Single Bevel Butt Weld:
It welds two parts with one edge shaped like a V-groove, while the other edge is a square.Single V Butt Weld:
It involves welding at an angle with both sides having bevel (v-grooves) angle.Single U Butt Weld:
It welds two surfaces with J-shaped edges, after the weld forms a shape like the letter 'U'.Single J Butt Weld:
It involves welding two pieces where one is J-shaped, while the other edge is square.Backing Run:
It is a method where a strip of metal is located on the opposite side to the actual weld in order to provide support for the first layer of metal. It is done to prevent the metal from escaping though the joint.Fillet Weld:
It welds two surfaces that are at right angles to each other.Plug Weld:
It is type of weld that is made when one metal part with circular hole is joined with another part placed right under it.Flare Bevel and Flair V Weld :
It is method of welding objects that form a convenient groove for welding, like a pipe surface.
Supplementary SymbolsWeld With Flat Face:
The dotted line indicates the weld side. The symbol on the near and far side represent the type of weld surface.Weld With Convex Face:
The near side or far side of the weld is a convex surface.Weld With Concave Face:
The weld or the opposite surface is concave in nature.
Complementary SymbolsSite Weld:
Also known as field weld, it indicates that the welding is to be done on the job site, instead of the workshop.Weld All Round:
It indicates that the welding should be done all around the joint.Weld Process Identification:
It denotes the specific welding process, if any, to follow.
Dimensioning WeldingIntermittent Fillet Welds:
These are not continuous welds, instead welds with specific pitch or distance between them. In certain cases, the welds are on both sides of the object. In that case, the fillets are placed in such a manner that the space between one side's weld will be the midpoint of the opposite side's weld.Seam Welding:
It is a type of continuous weld where the joint is made between or above two overlapping metal parts.