PSI - Issue 14

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Procedia Structural Integrity 14 (2019) 855–863

2nd International Conference on Structural Integrity and Exhibition 2018 Design and analysis of formed bellows for nuclear applications- Case study 2nd International Conference on Structural Integrity and Exhibition 2018 Design and analysis of formed bellows for nuclear applications- Case study

S.C.S.P. Kumar Krovvidi a,* , Sunil Goyal a , A.K. Bhaduri a a Indira Gandhi Centre for Atomic Research, Kalpakkam- 603102, India S.C.S.P. Kumar Krovvidi a,* , Sunil Goyal a , A.K. Bhaduri a a Indira Gandhi Centre for Atomic Research, Kalpakkam- 603102, India

Abstract Bellows are highly engineered components which find large number of applications in nuclear industry. Formed bellows are the most commonly used type of bellows especially when stoke is less than one thirds of bellows free length. Conventionally, design and manufacturing of the formed bellows are extensively addressed in standards of Expansion Joint Manufacturers Association (EJMA). In nuclear applications, design of the bellows shall comply with standard nuclear design codes such as ASME section III, RCC-MR etc, which follow design by analysis. Hence, the design of the bellows for nuclear systems needs detailed Finite Element Analysis (FEA) and fatigue life estimation as per the design curves given in the codes. In this work, a case study of design of formed bellows, made of SS316LN, operating below creep range for nuclear application is presented. The bellows are preliminarily designed by EJMA and the geometry arrived based on preliminary design is analyzed using FEA. The stress/ strain range in the bellows is estimated by both linear elastic and inelastic FEA. Non-linear isotropic-kinematic hardening constitutive model is employed for inelastic analysis of the bellows. The fatigue life of the bellows is estimated as per the guidelines given in RCC-MR. It is found that the fatigue life estimated by linear elastic analysis is more conservative as compared to inelastic analysis. In the design fatigue curves given in the nuclear design codes, factor of safety (FOS) of 2 on stress range is considered. By considering similar factor of safety on the equivalent stress given in EJMA, the cycle life of the bellows is estimated and compared with the design life obtained by detailed stress analysis. It is found that after including FOS of 2 on equivalent stress, the life predicted by EJMA design curve is conservative. Hence, FOS modified EJMA equation can be used for design of the nuclear bellows when operating temperature is less than creep range of the bellows material. Use of FOS modified EJMA design equation is easy and eliminates the need for detailed stress analysis by the bellows suppliers. However, other aspects such as manufacturing tolerances, inspection, testing and qualification of the bellows shall comply with standard nuclear design codes. © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. Abstract Bellows are highly engin ered components which fi d large number of applications in nuclear industry. Formed bellows ar the most commonly used type f b llows especially when stoke is l tha one thirds f bellows free length. Conventionally, des g and manufact ring of the formed bellows are extensively addressed in standar s of Exp nsion Joint Man facturers Association (EJMA). In nuclear applicati ns, design of the bellows shall comply with standard nuclear design cod s such as ASME section III, RCC-MR etc, which follow design by analysis. Henc , of the bellows for nucl ar sys ems needs detailed Finite Element Analysis (FEA) and fatigue life estimation as per the d sign curves given in the odes. In thi work, a cas study of design of form d bellows, made of SS316LN, oper ting below creep ange fo nuclear application is presented. The b llows re prelim arily designed by EJMA and the geometry arrived bas d on preliminary design is analyzed using FEA. The stres / strain rang in the bellows is estimated by both linear astic and inelastic FEA. Non-linear isotropic-kinematic ardening constitutive model is employed for inelastic analysis of the bellows. The f tigue life of the bellows is estimated as per the guid lines given n RCC-MR. I is found that the fatigue life es imated by linear elastic analysis is more conservative as compared t inelastic analysi . In the design fatigue curves give in the nuclear design cod s, factor of saf ty (FOS) of 2 on str ss range i consi ere . By consi er ng similar factor f saf ty on the equivalent stres given in EJMA, the cycle life of the bellows is estima ed and compared w th the design life obtained by detailed stress analysis. It is found that after incl ding FOS of 2 on equivalent stress, the ife predicted by EJMA design cu ve is con ervative. Hence, FOS modified EJMA equation can be used for design of the nuclear bellows when operating temperature is l ss than creep r nge of the bellows materia . Use of FOS m dified EJMA design equation is easy and elim ates he n ed for detailed stress analysis by the bel ows suppliers. However, other a pects such as manufacturing tolerances, inspection, testing and qualification of the bellows shall comply with standard nuclear design codes. © 2018 The Authors. Published by Elsevier B.V. This is a open access article und r the CC BY-NC-ND lic nse (https://creat vecommons.org/licenses/by- c-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers.

Keywords: Bellows; EJMA; RCC-MR; Finite element analysis Keywords: Bellows; EJMA; RCC-MR; Finite element analysis * Corresponding author. Tel.: +91-44-27480211; fax: +91-44-27480311. E-mail address: krovvidi@igcar.gov.in * Correspon ing author. Tel.: +91-44-27480211; fax: +91-44-27480311. E-mail address: krovvidi@igcar.gov.in

2452-3216 © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. This is a open access article und r the CC BY-NC-ND lic nse (https://creat vecommons.org/licenses/by- c-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. 10.1016/j.prostr.2019.07.064