LESSON VII ©
COPYRIGHT 2000 THE ESAB GROUP, INC. the
FCAW processes. SMAW requires a larger included angle and a considerable
root opening on
vee joints, so that the larger diameter of the coated electrode can reach down
into the joint to assure a good root
pass. Because of the smaller diameter of the flux cored
electrodes, the included angle may
be smaller, and in the case of the CO2 gas
shielded types
that have very deep penetration, the required root opening may be very small or
in some cases
eliminated. Figure 4 shows the calculated weight of the weld metal per foot
of weld for each
joint. The self-shielded flux cored joint requires .337 lbs (13%) less weld
metal than the shielded metal arc joint.
The gas shielded flux cored joint requires .970 lbs
(36%) less than the shielded metal
arc joint. 7.4.1.1
Comparable savings in the quantity
of filler metal can be achieved in fillet welds made
with the gas shielded flux cored process. Conventionally, fillet welds are
specified and
measured by the leg length of the largest triangle that can be inscribed in the
cross-section of the weld. The
load carrying dimension, the one that determines the strength
of the weld, is the throat dimension. Figure 5A shows a sketch of a typical
fillet weld made
with E7018 electrodes. The 1/2" leg weld that results in a throat
dimension of 0.35",
has a cross-sectional area of 0.125 square inches. This weld requires 0.425
pounds 2.691
lbs./ft. 2.354
lbs./ft. 1.721
lbs./ft. 1/4"
3/8"
3/16" 1"
1" 1"
FLUX CORED ARC WELDING VERSUS SHIELDED
METAL ARC WELDING WEIGHT
OF WELD METAL PER FOOT OF JOINT FIGURE
4 SHIELDED
SELF SHIELDED
GAS SHIELDED METAL
ARC FLUX CORED
FLUX CORED .35
THROAT .35 THROAT
1/2 LEG E7018
GAS SHIELDED FLUX
CORED 3/8
LEG A
B FILLET
WELD SIZE COMPARISON - SMAW vs. GAS SHIELDED FCAW FIGURE
5
