Les élastomères dans les industries pétrolière et parapétrolière

Elastomers in the Oil and Automotive Industries

Institut Français du Pétrole

Résumé

L'accroissement des contraintes subies par les matériaux utilisés dans les techniques pétrolières et parapétrolières et liées aux températures et pressions élevées ainsi qu'aux agressions chimiques, fait que l'on exige de ces matériaux qu'ils soient de plus en plus performants. Ceci implique, pour les concepteurs et utilisateurs de matériel comportant des élastomères en contact avec les hydrocarbures, une connaissance actualisée des produits existants, lesquels sont en constante évolution. On commence donc par décrire les principales familles d'élastomères résistant en milieu pétrolier actuellement disponibles sur le marché. Puis, après avoir évoqué les problèmes que rencontrent les industries pétrolière et automobile dans l'utilisation des élastomères et présenté sommairement les résultats de travaux réalisés à l'Institut Français du Pétrole (IFP), on définira quelques axes de recherches dont la finalité est de participer à l'amélioration des techniques pétrolières dans le sens d'une meilleure fiabilité et d'une réduction des coûts.

Abstract

The materials used in the oil and automotive industries are being subjected to higher and higher mechanical, thermal and chemical stresses, so these materials, and especially elastomers, have to be more and more resistant. For designers and users of equipment containing elastomers in contact with hydrocarbons, this requires an updated understanding of existing products. The aim of this article is thus to describe, first of all, the leading families of resistant elastomers now available for use in a petroleum environment, with particular emphasis on chlorinated, fluorinated, acrylic and nitrile rubbers and their derivatives, which have evolved greatly in recent years with the appearance of new varieties and new types of elastomers, such as Atlas, Vamac, Eypel, etc. For each family of elastomer, the structure is described along with the vulcanization method, its properties and its uses. Then the problems with which elastomers are confronted in the petroleum industry are described. They are mainly linked to the high pressures and temperatures encoutered in boreholes and to chemical attacks due to acid gases, corrosion inhibitors and completion and treatment fluids. Elastomers must also be resistant to blistering, extrusion and abrasion. The proper choice of a material can lead to a reduction in operating costs and to increased safety. Concerted action among elastomer producers and users seems indispensable. Problems in the automotive industry are linked to the increase in thermal stresses due to the raising of the temperature underneath the hood, to the use of new fuels, unleaded gasoline oxygenated fuel, and to the evolution of lubricant additives. This is leading to the progressive forsaking of nitrile rubber and polychloroprene to the benefit of higher-performance but more expensive elastomers such as fluorinated rubbers or hydrogenated nitrile rubbers. Fluorosilicones and acrylics are also being called upon for development in the automotive industry. Then several research findings made at Institut Français du Pétrole (IFP) are described, concerning the comparative analysis of the behavior of nitrile, hydrogenated nitrile and fluorinated rubbers in complex petroleum environments, together with a few examples of applications in the field of pumps, composite-material tubes with an elastomeric liner and gaskets. To conclude some suggestions are made on possibilities of improving elastomers for petroleum applications, based on a better understanding of the phenomenon of blistering, an improvement of vulcanization systems and the optimizing of some elastomers such as HNBR. Progress is also possible in the behavior of elastomers with regard to lubricants and fuels and in the predicting of the lifetime of seals used in boreholes.