TANK provides the ability to design or analyze tanks per API-650 or API-653. API-650 addresses the design, fabrication, erection, and testing requirements of above-ground, welded steel, atmospheric storage tanks. (API-653 is discussed below.) The following sections of API-650 are addressed by the TANK program.

Thickness Design
The tank shell course thicknesses (up to twenty courses per tank) can be evaluated according to any of the three methods set forth in API-650. While the One-Foot and Appendix A methods provide and exact solution, the Variable Point method is iterative in nature. In design mode TANK computes the required thicknesses (according to the specified method) for both the test and design cases. In analysis mode, the required thicknesses are determined, but then for subsequent computations, the user-specified course thicknesses are used.

Wind Girder and Stability
Following the thickness design, the requirements for the necessity of wind girders is evaluated. This procedure employs the Transformed Shell method and finishes with the selection of structural shapes suitable for the required section modulus.

Wind overturning stability is also evaluated, and if necessary the TANK program will compute the required anchorage.

High Temperature Adjustments per Appendix M
For tanks operating above 200 deg F, the material allowables and many of the constants in code equations must be modified. These modifications are made in accordance with the rules and tables of Appendix M.

Seismic Analysis per Appendix E
The user may also specify the data required to perform a seismic analysis. This analysis shows the acceptability of the tank for the design, test, and empty conditions. Anchorage is automatically designed if required.

Internal Pressure Analysis per Appendix F
When necessary, the TANK program evaluates the tank according to the rules of Appendix F. This evaluation may force a re-computation of the shell course thicknesses according to Appendix A.

Nozzle Flexibilities and Limiting Loads per Appendix P
Nozzles attached to the tank shell can be evaluated for limiting loads and flexibilities. The flexibility computation yields stiffnesses suitable for input into a piping program, such as CAESAR II. These stiffness then act as a restraint in the piping software. The limiting load computation yields the extreme values of the nozzle interaction diagrams. These diagrams can be plotted by TANK. If the actual nozzle loads, from a piping program such as CAESAR II, are specified, the TANK plots include the location of the interaction point. This enables the user to interpret the acceptability of the nozzle under the given loads. (Up to fifteen nozzles per tank can be specified for analysis.)

When necessary, the user may request a supported cone roof on a tank. The program will design a supported cone roof (rafters, girders, and columns) based on the procedures outlined in the text by Brownell & Young. The TANK program also plots a section view of the roof, with all pertinent parameters available.