Page 159 - Pressure Vessel Design Manual

Design of Vessel Supports 137

Table 3-14
Suggested Sizes of Legs and Cross-Bracing
Tan to Tan SUPPOfi Leg Base Plate Bracing Angle Bolt Size Y
Vessel O.D. (in.) Length (in.) Angle Sizes (in.) Size (in.) Size (in.) (in.) (in.)

Up to 30 Up to 240 (3) 3 x 3 x k 6x6x% 2X2X% % 12
up to 120 (4) 3 x 3 x % 6x6x% % 8
30 to 42 121 to 169 (4) 3 x 3 x % 6x6xX 2X2X?4 % 10
170 to 240 (4) 3 x 3 x % 6x6x% L 12
up to 120 (4) 3 x 3 x % 6x6x% 8
43 to 54 121 to 169 (4) 3 x 3 x % 6x6x% 10
170 to 240 (4) 4 x 4 x % 8X8X% 12
up to 120 (4) 4 x 4 x % 8X8X% 2% x 2% x ‘/4 1 8
55 to 56 121 to 169 (4) 4 x 4 x % 8X8XY2 1 10
170 to 240 (4) 4 x 4 x ?h 8X8XYZ 1 12
up to 120 (4) 5 x 5 x % 9X9X% 3X3X’/4 1% 8
67 to 78 121 to 169 (4)5X5X% 9X9X% 1% 10
170 to 240 (4) 6 x 6 x % 1OX1OX% 1% 12
up to 120 (4) 6 x 6 x Yz 10 x 10 x Y2 3X3X3 1% 10
79 to 80 121 to 169 (4) 6 x 6 x % 10 x 10 x Y2 178 12
170 to 240 (4) 6 x 6 x % lox lox% 1% 12
up to 120 (4) 6 x 6 x % 1OX1OX% 3X3X7* 1 78 12
91 to 102 121 to 169 (6) 6 x 6 x % 1OX1OX% 1% 12
170 to 240 (6) 6 x 6 x 1ox1ox~ 1% 12

3. Legs longer than about 7ft should be cross-braced.
4. Check to see if the cross-bracing interferes with piping
1. Cross-bracing the legs will conveniently reduce bend-
ing in legs due to overturning moments (wind and from bottom head.
equipment) normally associated with unbraced legs. 5. Shell stresses at the leg attachment should be investi-
The lateral bracing of the legs must be sized to take gated for local loads. For thin shells, extend “Y.” Legs
lateral loads induced in the frame that would other- should be avoided as a support method for vessels with
wise came the legs to bend. high shock loads or vibration service.
2. Legs may be made from angles, pipes, channels, beam
sections, or rectangular tubing.