Category Archives for Mechanical and Structural
Horizontal Vessels Saddle Supports and Stiffening Rings
Horizontal vessels are typically supported on two saddles. The use of two saddles is preferred both statically and economically over a system with more supports. The vessel designer should follow these steps: 1. Locate the position of saddle supports. 2. … Continue reading
Horizontal Ring Girders
Ring girders are typically used in elevated vessels when they are supported by a structural frame. The stress distribution in a ring girder is very complicated. Given a uniform load around the perimeter, the stresses and forces can be calculated … Continue reading
Vertical Vessel Lug Supports
The main design consideration regarding lug-supported vessels is the stress magnitude in the shell. Bijlaard’s method, as covered in WRC 107, is usually followed for the design. This method consists of determining the stress in the shell at the vicinity … Continue reading
Vertical Vessel Support Legs
Support legs can be made of wide-flange or pipe members. They are designed to resist axial loads, overturning moments, and lateral shear forces in the vessel. The attachment point to the vessel may cause high concentrated shell stresses which must … Continue reading
Openings in the Skirt
For skirt compression, deduct the width of openings, G (ft), around the perimeter of the skirt. The following equations take into account the shift in the neutral axis as well as the reduction in cross section. The equation for maximum … Continue reading
Vertical Vessel Skirts
The design procedure outlined here is based on cylindrical skirts. (Tapered designs are a special problem and beyond the scope of this manual.) Design of the skirt consists of determining the operating weight of the vessel and the controlling bending … Continue reading
Structural Supports
Process vessels are normally supported by one of the following methods (See Figure 400-19): • Skirts • Support legs • Support lugs • Ring girders • Saddles Skirts are typically used for vertical vessels because they are the most economical. … Continue reading
Internal Appurtenances Loads
For both vertical and horizontal vessels, internal appurtenances create loads that are directly applied to the vessel shell. These design concerns are best handled by the vessel designer, with input from engineers familiar with the process technology. (See below for … Continue reading
Horizontal Vessels Wind and Earthquake Loads
In horizontal vessels, wind and earthquake loads primarily affect the design of saddles and supports. The design of the shell is normally controlled by other loads such as design pressures, operating weight, saddle reactions, etc. A horizontal cylindrical vessel supported … Continue reading
Moment Amplification
Certain “slender” vessels are susceptible to increased stresses as a result of the eccentricity of the vessel weight in the deflected position. Slender vessels are defined as vessels with one of the following conditions: 1. Uniform diameter, and uniform mass … Continue reading