Keywords: metal seals, seal ring, high pressure, clamp connectors, leakage, non linear contact analysis.

Metal-to-metal seals are an effective and proven method through which to provide leak free sealing in high pressure pipeline applications. Metal - to - metal seals are often employed as sealing solutions in harsh environments such as in sub sea conditions and off shore platform applications. With a reliable high pressure design in production there is interest in extending the design into the low pressure regime. Despite many attempts to translate the design directly from the high pressure specification, this has proved to be somewhat unreliable.

This paper marks the start of a study into the cause of leakage, at low pressures, of metal-to-metal seals. The initial sections are concerned with producing a first finite element model of a seal using ANSYS [1]. These early simulations show how a seal behaves in a high pressure application with special reference to the interaction between the sealing faces, this is achieved using quadrilateral, eight-noded, plane strain elements to model the geometry of a hub and seal ring from a clamp type connector. Performed in the early stages as a purely elastic analysis this paper details the results of the later elastic plastic contact analysis.

The paper looks briefly at some of the equations derived by Dekker et al. [2] with regards to the design of pipe clamp connectors. Much consideration is also given to the next stages of the study, which include producing a fully 3D model of all of the components of a seal, also extending the FE model to some way take into account the surface finish of the sealing faces during loading. Mention is also made of the possibilities with regards to designing laboratory tests which could be used to confirm the computational findings.

It is hoped that the completion of this study will facilitate design rules which can be used to produce an effective leak free metal - to - metal connector which can operate in a variety of pressure conditions.

1

ANSYS, www.ansys.com.

2

C.J. Dekker and W.J. Stikvoort, "Improved design rules for pipe clamp connectors", International Journal of Pressure Vessels and Piping Volume 81, Issue 2, Pages 141-157, February 2004. doi:10.1016/j.ijpvp.2003.11.005

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