Nelson2015 Effect of Thermal Loading on Sealing

Original Article Effect of thermal loading on sealing behavior of single and twin-gasketed flange joints N Rino Nelson, N Siva Prasad and AS Sekhar Abstract Gasketed flange joints are usually subjected to internal pressure at high temperature. The most important requirement of flange joint is to provide leak-free joint under operating condition. In the present study, temperature-dependent nonlinear gasket properties of spiral-wound gasket at elevated temperatures are obtained experimentally and included in the analysis. The relaxation of gasket contact stress in both single and twin-gasketed joints at elevated temperatures is compared. It is observed that the ability to withstand internal pressure decreases with increase in temperature in both single and twin-gasketed flange joints. But, the twin-gasketed flange joint is found to withstand higher internal pressure than single-gasketed joint at a given bolt preload and temperature. The influence of gasket seating surface rotation on the distribution of gasket radial contact stress at elevated temperature is studied. The effect of elevated temperature on flange stresses of twin-gasketed joint is also examined. Keywords Gasketed flange joint, contact stress, twin gaskets, flange stresses, gasket nonlinearity, rotation Date received: 20 October 2014; accepted: 20 January 2015 Introduction Flange joints used in pressure vessels and piping sys- tems are usu ally sub jec ted to high int ern al pre ssure and high temperature. The knowledge of characteris- tics of the joint under internal pressure and elevated temperature is necessary to design a leak-free joint. Gas ket s are used in the se join ts to compen sat e for the irregu lari tie s in flan ge sur fac e and to pro vide a tight seal. Gasketed flange joints designed based on stan da rd code s such as ASME and DIN do not include the effect of temperature. Considerable work was done on the performance of gaske ted flang e joint under opera ting conditions . Ma et al . 1 worked on the behavior of metal-to-metal contact type gasketed joints (MMCG) under loading condit ions. They have used the temper ature -depen - de nt pr op er ti es of me tal- to-met al type gask et. Bili nea r kin ematic har den ing mat eri al mod el was used for flange members. The MMCG was found to be part ially efficie nt under internal and external loadings. Omiya and Sawa 2 investigated the effect of thermal loading on spi ral-wound gas ket, based on experi mental stu dy. They have observed that the thermal expansion coefficient of gasket is lesser than flange and bolt materials for temperature higher than 200 C. Vi no d et al. 3 ana lyz ed the flan ge joi nts in steam generator at elevated temperatures. The leakage in flan ge joi nt at higher ope rat ing temperature was found to be due to the di fferent ial expansion of flange and stud material. They incorporated sleeves, with higher coefficient of thermal expansion, between flange and nut to reduce the differential expansion. The sealing performance of box-shaped flange joint with silicone sheet at elevated temperature was inves- tigate d by Kawamura et al. 4 The effect of the rmal expansion was found to be greater than internal pressure on the joint sealing performance. The improve- ment in pe rfo rmance was observed wit h sil icone seala nt compar ed to sheet gaske t. Lee et al. 5 analyzed the gasket contact pressure distribution in an engine head, under different loading conditions. Their studies revealed that the thermal stress es enhan ced the gasket sealing, depending on the hold-down bolt forces. An effe ctiv e met hod of inc reasing the bol t pre load was propo sed for better performanc e. Abid et al. 6 investigated the joint strength of gasketed and nongasketed flange joints under operating conditions. The gasket Proc IMechE Part E: J Process Mechanical Engineering 0(0) 1–10 ! IMechE 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/095 44089155742 95 uk.sagepub.com/jpme Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, India Corresponding author: AS Sekhar , Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India. Email: [email protected] at Purdue University Libraries on June 19, 2015 pie.sagepub.com Downloaded from

Nelson2015 Effect of Thermal Loading on Sealing

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