Fig. 8.14 Single J preparation 6.0 DOUBLE V PREPARATION
Suitable for inside and outside corner joints provided there is no lamellar tearing. Also for horizontal-vertical position butt joints. Cheaper to prepare than asymmetric U for this purpose. |
g
P |
t= 12-50 mm ^ a ^ a = 60° s = 0-1.6 g = 1.6-6.3 mm |
P |
g |
=10-15° b2 = 45 - 40° |
Asymmetric preparation for horizontal-vertical position welding |
Requires less weld metal Balanced welding sequence Controlled distortion Large solid angle g Back gouging needed for efficient high quality joint
a |
Unequal preparation for joints fixed in flat position reducing overhead welding volume.
7. DOUBLE BEVEL PREPARATION
Thickness t = 19 to 51 mm a = 50 - 55° s = 0 to 1.6 mm g = 1.6 to 6.3 mm
Penetration on each side may be different to suit the requirements as in V preparation.
Cheaper to prepare than asymmetric double V for horizontal vertical position butt joints.
Fig. 8.16 (b) Double bevel preparation 8.0 DOUBLE U PREPARATION |
t > 38 mm a = 20° s = 1.6 to 3.2 mm g = 1.6 to 3.2 mm g = 6.3 to 9.5 mm |
a |
a |
p1 = 5 to 10° p2 = 25 to 20° |
9. DOUBLE J PREPARATION
Considerations mentioned in J-apply
here also
t > 38 mm a = 15 to 25° s = g = 1.6 to 3.2 mm Y = 9.5 to 12 mm
10. MIXED PREPARATIONS
Normal U one side, Flat bottomed U on the other side to facilitate back gouging.
Shallow reverse side allows cheaper V-prepa-
ration.
J
Combination of V and bevel where welding can be done easily from both sides.
Fig. 8.19 Mixed preparations