Transcript Document

Engineering
Drawing and Design
Seventh Edition
Chapter 18
18-1 Designing for welding
The primary importance of welding is to
unite various pieces of metal so that
they will operate as a unit structure to
support the loads to be carried
Welding processes include arc welding,
gas welding, and resistance welding (40
total processes exist)
Gas & Arc Welding
Most common form is oxyacetylene welding
gets heat from the burning of flammable
gases. It is slow compared to other modern
welding methods so is used primarily for
repair & maintenance
Arc welding is the major industrial welding
process-heat is generated by an electric arc
struck between a welding electrode, or rod,
and the workpiece. The arc is hot and
melting and solidification of the weld metal
occurs rapidly.
Resistance welding
Widely used especially for mass
production work
Heat is created from resistance losses
as a high amperage current is sent
across a joint between 2 mating
surfaces
Plug welding
A plug weld refers to joining two pieces
by welding through a hold in one of the
pieces*
WELDING DRAWINGS
TYPE OF JOINT
APPLICABLE WELDS
FILLET
PLUG
SLOT
SQUARE GROOVE
BEVEL GROOVE
J-GROOVE
FLARE BEVEL GROOVE
SPOT
PROJECTION
SEAM
BASIC WELDING JOINTS
WELDING DRAWINGS
TYPE OF JOINT
APPLICABLE WELDS
SQUARE GROOVE
V-GROOVE
BEVEL GROOVE
U-GROOVE
J-GROOVE
FLARE V-GROOVE
FLARE BEVEL GROOVE
EDGE FLANGE
BASIC WELDING JOINTS
WELDING DRAWINGS
TYPE OF JOINT
APPLICABLE WELDS
FILLET
SQUARE GROOVE
V-GROOVE
BEVEL GROOVE
U-GROOVE
J-GROOVE
FLARE V-GROOVE
FLARE BEVEL GROOVE
EDGE FLANGE
CORNER FLANGE
SPOT
PROJECTION
SEAM
BASIC WELDING JOINTS
WELDING DRAWINGS
TYPE OF JOINT
APPLICABLE WELDS
FILLET
PLUG
SLOT
BEVEL GROOVE
J-GROOVE
FLARE BEVEL GROOVE
SPOT
PROJECTION
SEAM
BASIC WELDING JOINTS
WELDING DRAWINGS
TYPE OF JOINT
APPLICABLE WELDS
PLUG
SLOT
SQUARE GROOVE
BEVEL GROOVE
V-GROOVE
U-GROOVE
J-GROOVE
BASIC WELDING JOINTS
EDGE FLANGE
CORNER FLANGE
SPOT
PROJECTION
SEAM
EDGE
The difference between Weld
symbol & Welding symbol…*
Weld symbol indicates
the type of weld
Welding symbol is a
method of
representing the weld
on drawings. It
includes
supplementary
information & consists
of the following 8
elements.








Reference line
Arrow
Basic weld symbol
Dimension and other
data
Supplementary
symbols
Finish symbols
Tail
Specification,
process or other
reference
18-2 Welding Symbols
Tail of the symbol designates the
welding specification, procedures, or
other information used to make the
weld*
Letters designate weld & cutting
processes (Table 18-3)
A-2, SAW, process specifications all can
be found in the weld tail symbol*
Location significance of Arrow*
Arrow side- for fillet, groove, flanged
weld symbols the arrow connecting the
welding symbol reference line to one
side of the joint
Other side – the side opposite the
arrow side
Both sides
WELDING DRAWINGS
WELD TERMINOLOGY
Weld terminology
Leg
Face
Throat
Groove radius
Root opening (groove weld) is the space
between the pieces before welding*
Root face
Groove angle
WELDING DRAWINGS
WELD TERMINOLOGY
WELDING DRAWINGS
WELD TERMINOLOGY
WELDING DRAWINGS
WELDING SYMBOLS
WELDING DRAWINGS
WELD TERMINOLOGY
WELDING DRAWINGS
WELD TERMINOLOGY
WELDING DRAWINGS
SINGLE
DOUBLE
FILLET
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
SQUARE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
BEVEL
GROOVE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
V-GROOVE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
J-GROOVE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
U-GROOVE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
FLAREBEVEL
GROOVE
FILLET AND GROOVE WELDS
WELDING DRAWINGS
SINGLE
DOUBLE
FLARE-V
GROOVE
FILLET AND GROOVE WELDS
Orientation of specific weld
symbols
Fillet, bevel-groove, J-groove, flaregroove, corner-flange welds symbols
are drawn with the perpendicular leg
always to the left
Break in arrow-when only 1 member of
a joint is to be prepared, the arrow has
a break and points toward that member
figure 18-9
Location of weld symbol wrt
joint*
Welds on the arrow side of the joint are
shown by placing the weld symbol
below the reference line
Welds on the other side of the joint are
shown by placing the weld symbol
above the reference line
Welds on both sides of the joint are
shown by placing the weld symbol on
both sides of the reference line
Field welds & All around welds
Field welds*
Not made in the shop or
at the place of initial
construction
Small black flag symbol*
is placed above and at
right angles to the
reference line
Figure 18-10
All around welds
Weld extending
completely around a joint
is indicated by a weld-allaround symbol placed at
the intersection of the
reference line and the
arrow
Figure 18-11
Not required for welds
extending around the
circumference of a pipe
More about weld symbols….
Combined weld
symbols figure 1812
Contours obtained
by welding
• Flat
• Convex
• Concave
Finishing of welds
grinding(G)
Chipping(C)
Machining (M)
Rolling (R)
Hammering (H)
Last slide on weld symbols
Multiple reference
lines indicate a
sequence of
operations to be
done at a single
location*
Tail of welding
symbol*



Welding process
Tables 18-3,18-4
Omitted when no
references are
required
WELDING DRAWINGS
COMBINED WELDING SYMBOLS
Design of welded joints
The size of the weld
should always be
designed with
reference to the size
of the thinner
member
Fillets welds are
cheaper and easier
to apply than groove
Full-strength fillet
welds joining 2
different thicknesses
of material should
be sized using a
table of
recommended full
strength weld sizes
based on the thinner
plate*
WELDING DRAWINGS
FINISHING OF WELDS
18-3 Fillet Welds & weld symbol
(WS)
Dimensions of fillet
welds are shown on
the same side of the
reference line as the
WS & to the left
Specify dimensions
of fillet welds on
both sides of a joint
Vertical part of fillet
weld symbol always
on left*
If using a general
note giving fillet
weld dimensions,
dimensions may be
left off WS
If dimensions differ
from general note
show them on WS
Length of weld
shown to right of
WS
More on fillet welds…
Staggered intermittent fillet welds are
designated in the weld symbol by
staggering where the weld symbol
appears on the reference line (p.652*)
Size of fillet welds
Table 8-5 p.651
A practical method to size fillet welds is
to design the weld for the thinner plate,
making it sufficient to carry 1/3 to ½
the carrying capacity of the plate.
WELDING DRAWINGS
COMPARISON OF A CAST SHAFT SUPPORT
WITH A WELDED STEEL SHAFT SUPPORT
18-4 Groove Weld symbol
Dimensions of groove weld are shown on the
same side of the reference line as the welding
symbol
When both sides of a double-groove weld
have the same (or different) dimension, both
sides are dimensioned, however the root
opening needs to appear only once
When a general note governs dimensions of
groove welds, groove welds need not be
dimensioned on the weld symbol
Back and Backing welds
Back or backing weld symbols are used
to indicate bead-type back or backing
welds of singe-groove welds
The back weld is made after the groove
weld
The backing weld is made before the
groove weld
WELDING DRAWINGS
APPLICATION OF BACK AND BACKING WELD SYMBOLS
18-5 Other basic welds
Plug
Slot
Spot
Seam
Surface
Flanged
Stud
WELDING DRAWINGS
OTHER BASIC WELDING SYMBOLS
AND THEIR LOCATION SIGNIFICANCE