• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1320-1329
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• 2024

When wall-thinning occurs in nuclear Class 2 and 3 pipes, reinforcement is typically applied rather than replacement. To analyze the structural integrity of reinforced wall-thinned pipe, stress analysis results using full 3-D FE analysis are not compatible to the design code equation, ASME BPVC Sec. III NC/ND-3650. Therefore, the efficient stress evaluation method for the reinforced wall-thinned pipe, compatible to the design code equation, needs to be developed. In this paper, stress evaluation methods for the reinforced wall-thinned pipe are proposed using the equivalent straight pipe concept. Furthermore, for fatigue analysis of the reinforced wall-thinned pipe, the stress intensification factor of reinforced wall-thinned pipe is presented using the structural stress method given in ASME BPVC Sec. VIII Div.2.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.18 no.2
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• pp.54-60
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• 2022

ASME BPVC provides stress evaluation rules for Class 2 and 3 nuclear piping. However, such rules are difficult to be applied to reinforced wall-thinned pipes during service. To resolve this issue, a new method for stress evaluation of reinforced wall-thinned pipes is proposed in this work, based on the equivalent stiffness concept. By converting a reinforced wall-thinned pipe to an equivalent straight pipe having the same stiffness, stress evaluation can be proceeded using the current ASME BPVC rules. The proposed method is applied to pipes with 4 different normal pipe size and the effects of reinforcement and wall-thinning dimensions on evaluated stresses are discussed.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.18 no.1
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• pp.11-18
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• 2022

When wall-thinning in a pipe occurs during operation of nuclear power plant, reinforcement of the pipe needs to be performed. Accordingly, the structural response of the piping system due to introduction of the reinforcement may be re-evaluated. For elastic structural analysis of the piping system with the reinforced pipe using finite element (FE) analysis, the stiffness of the reinforced pipe is needed. In this study, the stiffness matrix of wall-thinned pipe with pad reinforcement or composite reinforcement is analytically derived. The validity of the proposed equations is checked by comparing with systematic finite element (FE) analysis results.