Welding Symbols
Objective: SWBAT Identify and
explain welding symbols.
Introduction
Welding symbols are used on drawings,
project specs, and welding procedure
specifications.
They use a series of symbols to indicate the
joint configuration and weld type, location,
size, and length required.
Welding symbols are part of the language of
welding. Welders must be able to
understand this language to ensure their
welds meet the design specs.
Confused Yet?
Welding Symbol Base
The base for all welding symbols is the always
horizontal reference line with and arrow at one end.
The arrow which can come either end of the reference
line points to the location for which the welding
symbol applies.
Information on the reference line is always read from
left to right.
Welding Symbol Base
The opposite end of the arrow, or the tail is
used for information that aids in the
making of the weld but does not have its
owns place on the symbol. The tail can be
omitted when not needed.
Symbols for Welds
The weld symbol is used to identify the type
of weld to be made, signify a basic type of
weld joint, or identify the type of joint
preparation needed.
Weld Symbol Locations
The welding symbol
distinguishes between the
two sides of a weld joint by
using the arrow and the
space above and below the
reference line.
Information appearing above
the reference line refers the
opposite side of the joint that
the arrow is pointing to.
Information appearing below the
reference line refers to the
side of the joint that the arrow
is pointing to.
Weld Symbol Locations
Weld symbols appearing on both sides of the
reference line refer to both sides of the weld joint.
Weld Symbol Locations
Groove Preparation
The shape of the groove weld symbol indicates how
the groove is to be prepared. In the case of bevel
groove, and J-groove weld symbols only one of
the joint members to be welded is prepared.
The arrow indicates which member is to be
prepared by breaking towards that member.
Combining Weld Symbols
When more than one type of weld is to be made on
the same joint, it is necessary to combine weld
symbols.
The weld symbol is always placed on top of the
groove weld symbol, just as it would be on the
actual weld.
Size and Dimensions
Unless defined in a drawing note, the size data for a
fillet weld is always shown to the left of the
symbol for which it applies.
The length of the weld is always shown to the right
of the symbol.
Size and Dimensions
If the weld is to be an intermittent weld, the length
(length of each segment) and the pitch (center to
center spacing) are shown with a dash.
The length is always shown first and the pitch
second.
Size and Dimensions
If the welds are to be on both sides of the welds they
can be back to back or they can be staggered.
If the welds are back to back the symbols are lined up
evenly on both sides of the reference line.
If the welds are to be staggered the symbols above and
below the reference line are offset.
Size and Dimensions
A groove weld is a weld made in the groove when one or more of the
members has been beveled.
There are several items to be considered when sizing groove welds.
Groove preparation is the depth to which the groove penetrates into
the base metal.
When the groove prep extends all the way through the joint, no prep
size needs to be shown.
When the groove prep extends only part of the way through the joint,
the depth of groove is shown to the left of the symbol.
Size and Dimensions
If a root opening is required, the root opening
dimension of the groove weld is shown inside the
groove weld symbol.
Size and Dimensions
The angle for the type of groove is shown above or
below the welding symbol, depending on whether
the symbol is above or below the reference line.
Supplemental Symbols
Supplemental symbols are used to convey special instructions pertaining to
the welding symbol.
Weld-all-around is used when a weld is to extend completely around the
weld joint.
Field weld symbol indicates the weld is to be made on location.
When the face of the weld must have a finished shape that is not the aswelded condition a contour symbol is used.
When complete joint penetration is required a melt through symbol is used.
Surfacing Weld Symbols
Surfacing weld symbol always on arrow side
Applies to single or multiple layers
Size (thickness) to left of symbol
Location, direction of welding in tail or a drawing
reference
Spot Weld Symbols
The spot weld symbol may straddle the reference
line when there is no side significance, or be
placed on either side if significant.
Spot size or strength to left of symbol
Back and Backing Welds
The back and backing weld symbols are identical. The
sequence of welding determines which designation
applies.
Back weld made after groove weld
Backing weld made before groove weld
Weld Symbols Summary
Welding symbols are a language expressed
in graphic format and are used to convey
precise instructions about how a weld is to
be made.
By learning these symbols and the basic
rules for applying them, a welder can
easily understand how to precisely
prepare and make the required welds.
Understanding these symbols is essential
when using WPSs and Drawings.