J. Chattopadhyay et al., A DATABASE TO EVALUATE STRESS INTENSITY FACTORS OF ELBOWS WITH THROUGHWALL FLAWS UNDER COMBINED INTERNAL-PRESSURE AND BENDING MOMENT, International journal of pressure vessels and piping, 60(1), 1994, pp. 71-83
The advent of the leak-before-break (LBB) concept has widely replaced
the traditional design basis event of a double-ended guillotine break
(DEGB) in the design of primary heat transport (PHT) piping. The use o
f the LBB concept requires postulation of the largest credible cracks
at highly stressed locations and demonstration of their stability unde
r the maximum credible loading conditions. Stress analysis of PHT pipi
ng in nuclear power plants shows that the highly stressed piping compo
nents are normally elbows and branch tees. This necessitates detailed
fracture mechanics evaluation of such piping connections by computing
their stress intensity factors (SIF) and/or J-integral. Simple analyti
cal solutions for evaluation of the SIF and J-integral for cracks in s
traight pipes are readily available in the literature. However the sam
e type of solution for elbows and tees is limited in the open literatu
re. In the present work a database is generated to evaluate the SIF fo
r throughwall circumferential and longitudinal cracks under combined i
nternal pressure and bending moment. Different parameters used to char
acterise a cracked elbow are pipe factor (h), pipe bore radius to thic
kness ratio (r/t) and crack length. Another parameter (rho) is used to
consider the relative magnitude of stresses due to internal pressure
and remote bending moment. This database has been used to derive close
d-form expressions to evaluate the SIF for elbows with cracks in terms
of the aforementioned parameters.