Support Types of Vessels

 

1- Vertical Equipment

 Leg:

• Application: Small vertical drums to very large vessels and spheres up to 80 feet in diameter such as Spherical Pressurized Storage Tanks

• The maximum ratio of support leg length to drum diameter is typically 2:1.

• Cross bracing between the legs is typically used to help absorb wind or earthquake loads, specially for leg height more than 7 ft.

• More common in chemical industry

Lug:

• Application: Small to medium diameter Vertical Vessel (1 to 10 ft.)
• Light weight to heavy weight Application
• Reliable support
• Height-to-diameter ratios in the range of 2:1 to 5:1.
• The bolt holes are often slotted to permit free radial thermal expansion of the drum

Skirt:

• Application: Tall Tower

• A support skirt is a cylindrical/ conical shell section that is welded either to the lower portion of the vessel shell or to the bottom head (for cylindrical vessels).

• Skirts are welded to the vessel near the mid-plane of the shell.
• It is normally not necessary for the skirt bolt holes to be slotted

• The skirt is normally long enough to provide enough flexibility so that radial thermal expansion of the shell does not cause high thermal stresses at its junction with the skirt

• More common in refinery industry

2- Horizontal Equipment

 Saddle:

• One saddle support is normally fixed or anchored to its foundation. The other support is normally free to permit unrestrained longitudinal thermal expansion of the drum

• Number of Saddles: 2

Angle/ Nothing:

• Buried pressure vessels may be supported with two longitudinal angles to prevent from additional rotation during installation

Leg:

• It is not common but horizontal vessels may be supported with 4 legs