Storage tanks operating at elevated temperatures (200 °F to 500 °F) need to consider stresses due to thermal expansions and restraints, due to the tank shell and bottom plate interactions and operating conditions in addition to the design requirements for ambient temperature tanks. Appendix M of API Standard 650 provides additional requirements and guidelines for the design of tanks operating at elevated temperatures. These are based on Karcher's method which gives a simplified procedure for determining the stresses (strain range) in the tank wall and bottom plate. A factor named “C” is used for defining the ratio of actual expansion against free expansion of the tank. Such partial expansion causes significant thermal stresses. API uses these stresses to estimate the low cycle fatigue life of the tanks. At present, a range of C values (0.25–1.0) is allowed by API without clear guidelines for selecting a suitable value. In the absence of such guidelines, a set value (like 0.85) is being used irrespective of the tank dimensions and temperature change. The restraint against free expansion is mainly a result of the friction between bottom plate, the foundation medium and the ring wall (if present). We can estimate the C factor by relating it to the friction coefficient. This is explored in the present study. This paper evaluates the current procedure and suggests an alternate method by incorporating the friction coefficient directly in the stress equations, instead of the C-factor. Use of friction coefficient provides an improved basis for selecting C and avoids some of the difficulties.

References

References
1.
Long
,
B.
, and
Garner
,
B.
,
2004
,
Guide to Storage Tanks and Equipments
,
Professional Engineering Publishing
,
UK
.
2.
API Standard
,
2012
,
Welded Tanks for Oil Storage–API 650
,
11th
ed., American Petroleum Institute, Washington, D.C.
3.
Zick
,
L. P.
, and
McGrath
,
R. V.
,
1968
, “
Design of Large Diameter Cylindrical Shells
,”
Proceedings—API Division of Refining
,
American Petroleum Institute
,
New York
, Vol.
48
, pp.
1114
1140
.
4.
Jones
,
R.
, and
Seshadri
,
R.
,
1989
, “
Analysis and Design of High Temperature Storage Tanks
,”
Design and Analysis of Pressure Vessels and Components—1989 (ASME PVP Conference)
,
Vol. 175
,
pp. 45–5
2
.
5.
Denham
,
J. B.
,
Russell
,
J.
and
Wills
,
C. M. R.
,
1968
, “
How to Design a 600,000-BBL Tank
,”
Hydrocarbon Process.
, Gulf Pub. Co., Huston, TX,
47
(
5
), pp.
137
142
.
6.
Denham
,
J. B.
,
Russel
,
J.
, and
Wills
,
C. M. R.
,
1968
, “
Comparison of Predicted and Measured Stresses in a Large Storage Tank
,”
Proceedings of Division of Refining—API
, pp.
1034
1074
.
7.
Wu
,
T. Y.
, and
Liu
,
G. R.
,
2000
, “
Comparison of Design Methods for a Tank-Bottom Annular Plate and Concrete Ring Wall
,”
Int. J. Pressure Vessels Piping
,
77
, pp.
511
517
.10.1016/S0308-0161(00)00055-7
8.
Sathyanarayanan
,
S.
, and
Adluri
Seshu
M. R.
,
2011
, “
Effect of Annular Plate Projection Length on the Stresses in the Above Ground Steel Storage Tanks on Rigid Ring Wall Foundations
,”
Proceedings of ASME 2011 Pressure Vessel and Piping Conference
, July,
Baltimore, USA
.
9.
Karcher
,
G. G.
,
1978
, “
Thermal Stresses in Tanks Operating at Elevated Temperatures
,”
Proceedings—API Division of Refining
,
American Petroleum Institute
,
New York
,
57
, pp.
515
521
.
10.
Karcher
,
G. G.
,
1981
, “
Simplified Stress Equations for Elevated Storage Tanks
,”
Hydrocarbon Process.
, Gulf Pub. Co., Huston, TX, pp.
515
521
.
11.
Timoshenko
,
S.
, and
Woinowsky-Kreiger
,
S.
,
1989
,
Theory of Plates and Shells
,
2nd
ed.,
McGraw-Hill
,
New York
.
12.
Hetenyi
,
M.
,
1971
,
Beams on Elastic Foundation
,
The University of Michigan Press
,
Ann Arbor, MI
.
13.
Boresi
,
A. P.
, and
Schmidt
,
R. J.
,
1993
,
Advanced Mechanics of Materials
,
5th
ed.,
John Wiley & Sons, Inc.
,
New York
.
14.
Adluri
Seshu
,
M. R.
,
2012
,
Friction Effects on the Bottom Plate of Large Elevated Temperature Steel Tanks
,
Research Report, Faculty of Engineering
,
Memorial University
,
NL, Canada
.
15.
ansys
,
2011
, University Research Version 11.0, SASIP, Inc.
16.
ansys
,
2011
,
Contact Technology Guide
, Release 9.0.
17.
Sathyanarayanan
,
S.
, and
Adluri
Seshu
,
M. R.
,
2012
, “
Modifications to the Stress Value Computation for Fatigue Analysis of Shell-to-bottom Joint of Steel Tanks on Concrete Ring Wall
,”
Proceedings of ASME 2012 Pressure Vessel and Piping Conference
, July,
Toronto, Canada
.
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