Lubis, Asnawi and Tanti, Novri and Tambunan, Rizki Rian Toni (2018) Flexibility of S-Shaped Pipe Bends under Thermal and Mechanical Loads. Prosiding Seminar Nasional Tahunan Teknik Mesin (SNTTM) ke 17. PMT-19/112-117. ISSN 2623-0313

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Curved pipes or pipe bends and elbows are widely used in piping systems. One of its functions is to change the direction of fluid flow. Pipe bends and elbows are also often used to absorb thermal expansion because its additional flexibility under bending compared to an equivalent straight pipe of the same geometry and material properties. The augmented flexibility of a pipe bend is due to its cross section become oval under bending load. For in-plane closing bending moment load, the major axis of the oval cross-section is perpendicular to plane of the bend, for in-plane opening bending, the major axis lie on the plane of the bend. Current ASME piping code treats the flexibility factors equally for all values of subtended angles, being only a function of pipe bend parameter λ. The flexibility of pipe bends when they are combined, such as S-shaped back-to-back pipe bends, are not considered in current piping codes. The flexibility factor itself is originally defined as the ratio of end rotation of a pipe bend to the end rotation of an equivalent straight pipe under the same bending load. It is noted that the loading considered is bending moment – a mechanical load. However, if piping system is well supported, the bending moment as mechanical load is not a significant load. In fact, thermal load resulting thermal stress and internal pressure load are dominant in many industrial piping systems. This paper presents results of finite element analysis of flexibility factors of S-Shaped back-to-back pipe bends under thermal load. ANSYS shell and beam element were used in this analysis. For boundary conditions, one end of the straight tangent was fully fixed for all nodal degree of freedom, while the end of the other straight tangent was simulated as guided cantilever. In this analysis, flexibility factor is redefined as the ratio of end rotation of S-Shaped pipe bends due to thermal obtained from finite element analysis to the theoretical end rotation of equivalent straight pipe due to moment bending. The moment bending applied to straight pipe is obtained from the reaction moment due to thermal load in S-Shaped pipe bend. The results shows that flexibility factors of S-shaped pipe bends under thermal load are small compared to the ASME B31 flexibility factors.

Item Type: Article
Uncontrolled Keywords: S-Shaped pipe bend, flexibility factors, thermal load
Subjects: T Technology > TJ Mechanical engineering and machinery
Divisions: Fakultas Teknik (FT) > Prodi Teknik Mesin
Depositing User: Dr Asnawi Lubis
Date Deposited: 14 Nov 2018 02:48
Last Modified: 14 Nov 2018 02:48

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