Failure of pressure vessels and piping systems that operate at high temperatures can occur by net section rupture, creep crack growth or a combination of both processes. Several design and assessment procedures are available for dealing with this situation. These include the ASME Pressure Vessel and Piping, French RCC-MR (Appendix 16) and British R5 and BS7910 codes. Each of these procedures uses a combination of continuum mechanics and fracture mechanics concepts to make an assessment. Although the procedures adopt the same basic principles, often different formulae are employed to make an assessment. The main parameters that are used are reference stress, σref, stress intensity factor, K, and the creep fracture mechanics term C*. In this paper, an analysis is performed to estimate the sensitivity of the predictions of creep crack growth in a pressurised pipe to the choice of formulae used and materials properties employed. It is shown that most sensitivity is obtained to choice of expression employed for calculating σref and to whether batch specific or more generic materials properties data are selected.
CREEP CRACK GROWTH IN 2219-T851 ALUMINUM ALLOY: APPLICABILITY OF FRACTURE MECHANICS CONCEPTS