Influence of Initial Defect Distribution on the Life of the Cold Leg Piping System
There are two basic design philosophies to avoid fatigue fracture presently contained in the ASME Boiler and Pressure Vessel Code. One, safe life, provides for fatigue resistance by avoiding the initiation of cracks, whereas the second, damage tolerance, presumes the existance of cracks and defects and guards against their unstable growth. This paper examines the utility of these approaches in the context of the sensitivity of piping system life to the character of the presumed initial defect distribution. The importance of defect detectability and growth monitoring is illustrated and the significance of parameters like defect size and shape to damage tolerant approaches discussed, in terms of piping system life. Results of the paper are interpreted in light of relevant NDI capabilities and requirements.
KeywordsFatigue Crack Growth Linear Elastic Fracture Mechanic Piping System Circumferential Crack Elastic Plastic Fracture Mechanics
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- 1.D. Broek, Elementary Engineering Fracture Mechanics, Noordhoff International Publishing, Leyden, The Netherlands, (1974).Google Scholar
- 2.G. R. Irwin, Analysis of Stresses and Strains Near the End of a Crack Traversing a Plate, Transactions, Amer. Soc. of Mech. Eng., Journal of Applied Mechanics, (1957).Google Scholar
- 3.H. A. Wood, and R. M. Engle, “Damage Tolerant Design Handbook”, AFFDL-TR-79–3021, (1979).Google Scholar
- 4.M. E. Mayfield, T. P. Forte, E. C. Rodabaugh, B. N. Leis, and R. J. Eiber, “Cold Leg Integrity Evaluation”, NUREG/CR1319, (1980).Google Scholar
- 5.“PVRC Recommendations on Toughness Requirements for Ferritic Materials”, Welding Research Council Bulletin 175, (August, 1972).Google Scholar
- 6.W. H. Bamford, “Application of Corrosion Fatigue Crack Growth Rate Data to Integrity Analyses of Nuclear Reactor Vessels”, ASME Paper Number 79-PVP-116, (1979).Google Scholar
- 7.P. C Paris, R. J. Bucci, E. T. Wessel, and T. R. Mager, “Extensive Study on Low Fatigue Crack Growth Rates in A533 and A508 Steels”, Stress Analysis and Growth of Cracks, ASTM STP 513, (1972).Google Scholar
- 8.W. H. Bamford, and D. M. Moon, “Some Mechanistic Observations on the Crack Growth Characteristics of Pressure Vessel and Piping Steels in PWR Environment”, Paper 222, Presented at NACE Corrosion/79, Atlanta, Georgia, (March, 1979).Google Scholar
- 9.J. F. Kiefner, W. A. Maxey, R. J. Eiber, and A. R. Duffy, “Failure Stress Levels of Flaws in Pressurized Cylinder”, Progress in Flaw Growth and Fracture Toughness Testing, ASTM STP 536, (1973).Google Scholar
- 10.M. F. Kanninen, et al, “Mechanical Fracture Predictions for Sensitized Stainless Steel Piping With Circumferential Cracks”, EPRI ND-192, (September, 1976).Google Scholar