WELD SYMBOLS ON ENGINEERING DRAWINGS
The main purpose of
welding symbols on drawing is to transfer the information from design
department to workshop.
Welding symbols used to reduce
the number of words on engineering drawing so we can save time and
space.once we familiar with weld symbols, we understand the actual weld of that
particular joint.
Numbers, root gap root space,
groove angle, length of the weld, type of welding to be done etc. all
information expressed by welding symbol because of this the welding symbols on engineering
drawings expressed large no. of information of given weld.
Without good and
proper knowledge of WELD SYMBOLS the welding inspector unable to understand the
scope of work. It is important to understand clear and exact meaning of symbols
in engineering drawings for proper work. Below show some important parameters
which should know the welding inspector as,
The
arrow line:
- Reference line:-
Always the reference line must touch to the arrow line which is
generally parallel. This line shows the weld joint of job by arrow the symbol
shown below,
- Symbolic Representation :-
The
symbol is mostly same in the all codes & standard only slightly
differences as per different standards ,the concept of arrow side
and other side may differ from standard to standard.
- Other Information :-
In
other information consisting welding process, type of
geometry, type of NDT, welding profile and other supplementary requirements as per
client which differ from standard.
In fabrication work the mostly used some of weld joints shown below,
I)
SITE JOINT WELD SYMBOL :
Sometimes some items
or part of job welded at site and required to dispatch with job in such
cases flag type weld symbol used as shown below, Ex. Washer of base in in
pressure vessels is not welded by manufacturer required to welded at site after
installation of job in such cases the side weld symbol is used.
II) WELD ALL AROUND WELD SYMBOL :
COMMON USED WELD SYMBOLS IN ENGINEERING DRAWING.
Shown below the
common in general work used symbols,
A) SINGLE/DOUBLE BEVEL JOINT :
In joint if bevel cuts in one direction (either
left or right) of the given joints called single beveled joint and if bevel
cuts in both direction of given joint called double beveled.
B) SQUARE BUTT WELD JOINT :
Two flat parts which parallel to each other joints welded by
square but weld as symbol shown above fig. square butt welding generally done
by gas or arc welding this type of welding is simple as compared to other type
of welding but some restrictions forms due to thickness of joint.
C) SINGLE/DOUBLE V WELD JOINT :
Single v weld joint is mostly similar to bevel joint only
difference is that in bevel joint only on side is beveled instead of in single
v both edges beveled also in double v all edges beveled. Generally single v is
used when the job material thickness up-to 19.05 mm & double v is used when
job material thickness exceeds 19.05 mm.
D) SPOT WELD JOINTS :
the welding of
overlapping pieces of metal at small points is done by spot welds.The
welding is prefer unto job material thickness 3 mm.
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