Service Life Estimation
High Pressure – High Temperature Testing to Failure
Estimating the useful service life of rubber and polymers is of utmost interest to many of our clients. This work takes the form of accelerated aging whereby elevated temperature exposure to a simulated operating environment is used to hasten the process of degradation. Various models can be applied to resulting data such as Arrhenius, diffusion limited oxidation (DLO), time-temperature superposition master curves and Williams-Landel-Ferry (WLF) or power law treatments. While many standard test methods (such as ISO 23936) invoke a threshold change in a key parameter, such as tensile strength, to denote ‘failure’, Argen is also equipped to execute testing in a more realistic manner, especially for high pressure sealing applications. We design, build, and operate automated high pressure test rigs that cycle temperature and pressure according to an operator input algorithm until the seal actually fails. API TR 6JI describes such an approach in general terms. The test rigs at Argen are multiplexed to enable simultaneous testing of dozens of specimens, are PLC controlled with custom complex logic to detect failure, and are complete with a graphical user interface for continuous monitoring and intervention when necessary. They are built with corrosion resistant alloys to enable operation in everything from nitrogen gas to high temperature brines.
Compressive Stress Relaxation
Argen experts apply Compressive Stress Relaxation methods to assess loss of elasticity and ‘sealing force’ for static sealing applications, coupling mechanical testing with exposure to thermochemical environments. These methods offer an alternative approach to service life estimation that can in some cases be more representative than conventional testing based on tensile properties.