| Oil
Storage Tanks Design & Analysis Software
TANK is a comprehensive engineering software program that
designs and analyses oil storage tanks according to the latest API-650
and API-653 codes
For much less than it would cost to build an in-house spreadsheet
application, TANK delivers the features and stability typical of
a COADE software product, including immediate, top-rate technical
support.
TANK is much more than the computerisation of a time consuming engineering
task.
Its development was shaped by the input of many “API-650/653
expert” engineers whose influence ensured that TANK performs
the required tasks effectively and efficiently. A menu-driven scroll-and-select
interface provides logical options when and where expected. Context-sensitive
help provides instant technical assistance for each data field,
with code references as often as possible.
The program also provides control options for everything from calculations
to screen colours, allowing the customisation of the TANK environment
on a directory basis. Options affecting computations include 1988,
1993, 1994, 1995, 1996, 1997 material databases, corroded nozzles,
corroded hydrotest, corroded wind girder calculations, and wind
pressures.
A material data base editor is provided so the software can address
additional materials not included in the code. The program also
provides several standard units files, which if not sufficient,
can be used to generate other, custom units files. Completed jobs
can be converted to other units systems as client requirements dictate,
without rerunning the analysis.
Operational Features
Menu / Spreadsheet Interface
The menus are set up to present the available program options in
a logical order, the way a job would typically be accomplished.
Each menu option provides “help” for assistance whenever
necessary. Most menus provide a recovery or escape option in case
of errant selection. Shell course data (thicknesses, heights, corrosion,
and material properties) can be duplicated by the program, thereby
reducing the amount of input required from the user. There is also
a spreadsheet for the estimation of tank size versus cost, which
can serve as a starting point for additional tank calculations.
Integrated Error Checking
The TANK program includes an integrated error checker, which is
automatically run following the completion of the input specification.
This error checker analyses the user-specified input and checks
it for consistency and compliance with the API code rules. Two types
of messages are generated by this error checker, warnings and fatal
errors. Warning messages are conditions that may be errors, but
are numerically acceptable. For example, warning messages are generated
when shell course heights are defined less than six feet, or nozzle
analysis is requested for tanks with diameters less than one hundred
twenty feet. Fatal error messages are generated when the specified
input data is inconsistent or illogical, for example if the corrosion
allowance is larger then the corresponding jobs can be analysed
with warning messages, but not with fatal error messages. Warning
messages are available for inclusion in the final output reports.
Interactive Report Review
Once a job has been analysed, the solution results are available
for review at any time. The review module is interactive, allowing
the selective review of individual output reports. A pre-output
processor is available to create new reports or to append to existing
reports. Added reports can be generated in units systems different
from previous reports, providing data review suitable for a variety
of purposes.
Reports can be annotated by the user, to highlight or explain specific
points of interest (program generated data lines may not be altered).
Reports can be viewed on the terminal screen, or sent to a printer
or to a disk file.
Material DataBases and Editor
The TANK program is installed with four material libraries. The
user simply selects the desired data base in the configuration module,
to activate a set of materials for future use.
Digitized Code Data
Wherever possible, the data from the figures and tables of the codes
have been digitized and are incorporated into the TANK program.
The program incorporates its own interpolation routines so that
users no longer need to estimate data values from the code.
Graphics Display of Solution Data
Depending on the specifics of the job, various graphics displays
may be available. The TANK program provides a graphical review of
the results of nozzle interaction diagrams, supported cone roof
design, and shell out-of-plane settlement.
Analysis and Design Capabilities
TANK provides the ability to design or analyse 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 an
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.
Allowed Fluid Heights
For either the design or analysis modes, the allowed fluid height
above the bottom of each course is reported. This table shows, for
the non-governing load case, exactly how much fluid can be stored
without over stressing the tank shell. This table is especially
useful in analysis mode, when the actual thickness is less than
desired.
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 200º 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. This
stiffness then acts 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.)
Stainless Steel Adjustments per Appendix
S
Addendum 2 to the 9th Edition of API-650 includes a new appendix,
Appendix S. This appendix provides material properties and modified
equations for the analysis of stainless steel tanks. In addition,
Appendix S modifies the interpretation of many paragraphs in other
chapters of the code, for stainless steel tanks.
Supported Cone Roof Design per Brownell
& Young
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.
API-2000 Venting Requirements
As an option, the venting requirements of the tank (for inbreathing,
outbreathing, and fire exposure) can be computed according to API-2000
5th Edition.
API-653 Capabilities
API-653 provides minimum requirements for maintaining the integrity
of welded or riveted, non-refrigerated, atmospheric pressure, above-ground
storage tanks after they have been placed in service. This code
covers the maintenance inspection, repair, alteration, relocation,
and reconstruction of such tanks. The following sections of API-653
are addressed by the TANK program.
Material Adjustments per Section
2.3
An API-653 analysis begins with a recalculation of the minimum required
shell thickness. However, this computation uses an allowable of
SE, where both are determined by the code.
Remaining Corrosion and Retiring
Thicknesses
For API-653 analysis, an additional report follows the shell thickness
report. This additional report details the remaining corrosion allowance
and the retiring thickness on a per course basis.
Individual Course Values of “L”
and “E”
For tanks that may need closer evaluations, the TANK program provides
the ability to specify a joint efficiency on a per course bases.
In addition, the user may specify the distance from the bottom of
each course to the “L” value.
Evaluation Using T1 and T2
Further analysis refinements are possible by specifying both t1
and t2 for each tank course. When this data is specified, additional
output tables are produced to show allowed fluid heights, remaining
corrosion, and retiring thickensses.
Evaluation of Shell Settlement per
Appendix B
In an effort to reduce shell stresses, out-of-roundness, and floating
roof bindings, the shell settlement can be analysed. This evaluation
begins with settlement measurements. The results can be reviewed
in tabular form, or plotted. The results include the optimum cosine
curve, the out-of-plane settlement, and the out-of-plane deflection.
Amir M. Heshmati is the managing director of ImageGrafix. He
can be reached at amheshmati@image-grafix.com
|
