The search for usable reserves of oil and gas is taking operators into more remote and arduous environments, many of which are in the coldest regions of the world. This raises a challenge for elastomeric seal manufacturers as conventional elastomeric materials start to lose effectiveness as they become stiffer and lose resilience as the temperature drops. The members of the ESA Elastomeric and Polymeric Seals Division are rising to this challenge as they develop new compounds and seal designs to accommodate extreme low temperature operation.
These seals need to be tested to demonstrate their effectiveness at low temperature. There are numerous acceptable test methods to show the properties of the materials themselves at low temperature, such as torsion modulus, brittleness, compression set and temperature retraction. But these in themselves do not give a direct indication of whether a seal will continue to function. There are also proprietary functional test procedures which aim to identify the minimum operating temperature for seals; however all of these rely on the seal being energised by the pressure of the test fluid prior to being subjected to low temperature. This is not normally the case as in real applications the seal will have been kept at low temperature prior to being exposed to the pressurising media and because it has already stiffened may not then be able to energise to maintain a seal.
So a project has commenced to prepare and validate a suitable test method for this common but more severe condition. An initial draft of the standard has been prepared and is nearing a point whereby its validity can be tested. Therefore the next stage will be a validation programme which will take the form of round- robin tests conducted by the members on typical seals obtained from a single source. Each laboratory will test seals and the results will be compared for consistency and repeatability before refinement of the specification.
This will result for the first time in an industry agreed specification that all reputable seal suppliers will be able to use to give end-users reliable guidance on the low temperature operating limits of their compounds. It is anticipated that the test procedure can subsequently be put forward to ISO for development into a truly international standard.