Low pressure gaskets for gas pipelines

Abstract

Investments in gas distribution networks are very high, exceeding worldwide hundreds of billions of euros. The replacement of pieces too early results loss of capital. However, by too late replacement safety and security of supply may be in serious danger. This project is focused in distribution pipelines, composed of several interconnected pipelines with small diameters and low pressure, used to take the products to the final consumer. More specifically union joints and flange gaskets are studied. In the field of gasket and seals, gaskets are generally associated with mating flanges of a mechanical joint while seals are generally associated with moving parts. Some designers refer to gaskets as static seals but this is not really true since the relationship between a gasket and its mating flanges is dynamic in nature due to the dynamic deformations associated with internal pressure, vibration, external forces and thermal expansion or contraction. The main objective of this project is the study of low pressure gaskets for gas pipelines. Some gas companies are continuously spending money and resources on improve the lifetime of their installations and achieve the regulations required. The first part of this paper is an analysis and description of gasket design, including calculation of union joints, styles of flanges and factors that affect the performance. Then a description of the common gasket materials and gasket configurations is done, complemented with installation advices and troubleshooting. Following, a complete description of standardized test procedures for determination of leakage, creep and stress relaxation of gasket materials is done, using information from different sources like ASTM, DIN, EN and ISO standards. A compilation of test equipment found in standards and other references is another important part of this study, with a mechanical analysis of the schematic sketches related to each tester, and possible developments in machine design following the knowledge obtained in this topic. Finally takes the processing of data obtained experimentally in laboratory with the comparison of two common gasket materials used in gas pipelines and how to present the obtained results in a useful report addressed to potential consumers.