This paper comments on using the Larson-Miller parameter to fit the creep-rupture life distribution as a function of temperature and stress. The commonly used least-squares linear regression method assumes that the creep-rupture life follows the lognormal distribution. Most engineering literature does not discuss the validity of this assumption. In this paper, we outline the procedure for validating two critical assumptions when the least-squares method is used. The maximum likelihood method is suggested as an alternative and more powerful method for fitting creep-rupture life distributions. Examples are given to demonstrate the use of these two methods using Microsoft Excel and the LIFEREG procedure in SAS. [S0094-9930(00)00504-7]

Issue Section:
Technical Papers
Keywords:
creep, creep testing, pressure vessels, Creep, Larson-Miller Parameter, Data Analysis, Life Distribution, Least-Squares Method, Maximum Likelihood Method
Topics:
Creep, Fittings, Rupture, Stress, Temperature
1.
Boyer, H. E., 1988, Atlas of Creep and Stress-Rupture Curves, ASM International, Metal Park, OH 44073.
2.
Larson
,
F. R.
, and
Miller
,
J.
,
1952
, “
A Time-Temperature Relationship for Rupture and Creep Stress
,”
Trans. ASME
,
74
, p.
76
76
.
3.
Jaske, C. E., and Simonen, F. A., 1991, “Creep-Rupture Properties for Use in the Life Assessment of Fired Heater Tubes”, Proc., First International Conference on Heat-Resistant Materials, ASM International Materials Park, OH, pp. 485–493.
4.
American Petroleum Institute, 1988, “Calculation of Heater-Tube Thickness in Petroleum Refineries,” API Recommended Practice 530, 3rd Edition.
5.
Nelson, W., 1990, Accelerated Testing: Statistical Models, Test Plans, and Data Analysis, Wiley, New York, NY.
6.
Conway, J. B., 1969, Stress-Rupture Parameters: Origin, Calculation and Use, Gordon and Breach, New York, NY.
7.
Orvis, W. J., 1996, Excel for Scientists and Engineers, Sybex, San Francisco, CA.
8.
Draper, N. R., and Smith, H., 1981, Applied Regression Analysis, 2nd Edition, Wiley, New York, NY.
9.
Freung, J. E., and Walpole, R. E., 1980, Mathematical Statistics, 3rd Edition, Prentice-Hall, Englewood Cliffs, NJ.
10.
The SAS Institute, 1990, SAS/STAT User’s Guide, Vol. 2, Version 6, Fourth Edition.
Copyright © 2000
 by ASME
You do not currently have access to this content.