This document provides general principles, requirements and recommendations for the assessment of the stability of thermoset materials that include short fibre filled or particle filled resins and exclude continuous fibre reinforced composites for service in equipment used in oil and gas exploration and production environments. This document also provides guidance for quality assurance. It supplements but does not replace, the material requirements given in the appropriate design codes, standards or regulations. This document addresses the resistance of thermosets to the deterioration in properties that can be caused by physical or chemical interaction with produced and injected oil and gas-field media, and with chemical treatment. Interaction with sunlight and ionizing radiation are excluded from the scope of this document. This document is not necessarily suitable for application to equipment used in refining or downstream processes and equipment. The equipment considered includes, but is not limited to, non-metallic pipelines, piping, liners, seals, gaskets and washers. Applications for short term exposure include pump-down plugs, bridge plug components, line wiper plugs, balls, setting tools and fracking tools. Applications for long term exposure include bearings and washers. This document excludes tubular products, tanks and similar items produced from continuous fibre reinforced materials. Blistering by rapid gas decompression is not included in the scope of this document. This document applies to the assessment of the stability of non-metallic materials in simulated hydrocarbon production conditions to aid the selection of materials for equipment designed and constructed using conventional design criteria. Designs utilizing other criteria are excluded from its scope.