Structural Analysis and Experimental Study on the Spherical Seal of a Subsea Connector Based on a Non-Standard O-Ring Seal

Dong Liu,Xiujun Xu,Xiaoquan Hao,Feihong Yun,Kefeng Jiao,Peng Jia,Liquan Wang,Weifeng Liu,Xiangyu Wang,Zheping Yan

doi:10.3390/jmse10030404

Dong Liu, Xiujun Xu + Show 8 more

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https://doi.org/10.3390/jmse10030404

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Abstract

Underwater oil and gas pipelines are prone to alignment differences and angle offsets during docking, and the spherical flange connector can address this problem. Its main function is to enable compensation of the different angles of the pipeline during docking and to apply a non-standard spherical sealing structure using O-rings to the connection. In this paper, the study of a spherical sealing structure using O-rings was based on a spherical structural model of the connector. The Mooney–Rivlin constitutive equation and material parameters of the O-ring were determined according to nonlinear theory. The structure of the non-standard spherical sealing groove was designed and analysed with reference to the standard sealing groove, the calculation expression of the spherical groove specific size was deduced, and the width and depth of the groove were determined. A finite element analysis of the non-standard O-ring sealing structure was carried out using ANSYS Workbench software; the effects of different pressures and compression ratios on the O-ring sealing performance were analysed and studied in terms of von Mises stress, contact pressure and contact width of different contact surfaces so as to determine a more reasonable compression ratio in the sealing structure. Finally, the theoretical analysis of the non-standard spherical sealing structure using O-rings was validated by testing, and it was proven that it could maintain a good seal under high pressure.

Highlights

IntroductionAs a key part of offshore oil and gas engineering equipment, subsea connectors are mainly used for pipeline connection in subsea production systems [1,2]
To fill this research gap, using an analysis of spherical O-ring sealing structures, this paper aimed to study and analyse the material parameters of the O-ring, and to determine the influence of a non-standard spherical sealing groove and pressure and compression ratios on sealing, to provide a reference for future scholars
Referring to the dimensional design of a standard shaft structure groove, the dimensional design of the spherical groove was developed from the perspective of groove volume and O-ring volume, and the width and depth of the spherical groove were determined to be 9.5 mm and 5.85 mm, respectively, and the installation position of the O-ring was determined

Summary

Introduction

As a key part of offshore oil and gas engineering equipment, subsea connectors are mainly used for pipeline connection in subsea production systems [1,2]. The working environment of underwater connectors features high pressure and low temperature, and the influence of ocean currents [3]. As a flexible structure that can realize multi angle transformation, a spherical structure is increasingly being used in the design of underwater connectors. Problems related to alignment differences of the parts being connected may occur due to installation error; the advantage that the spherical structure has is that it can achieve angle compensation, and so is a good solution to this problem. In 1976, Watkins et al [4] designed a flexible support joint, which is composed and connected by ball structure and socket-like structure. In 2011, Moon, Il Yoon [6] applied a spherical seal in the low-temperature and high-pressure pipeline of a liquid fuel rocket engine, and a hermetic seal was realized inside it

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