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

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