Entity

Time filter

Source Type

Shawbury, United Kingdom

Hulme A.,Smithers Rapra | Cooper J.,Smithers Rapra
Sealing Technology | Year: 2012

This article discusses the different effects of the operating environment on polymers when they are subjected to both static and dynamic loads. It discusses ageing mechanisms - for example, oxidation, thermal degradation, chemical attack and plasticisation - which can occur during service and it looks at the test methods that are available to characterise performance. © 2012 Elsevier Ltd. Source


Hulme A.,Smithers Rapra | Cooper J.,Smithers Rapra
Gummi, Fasern, Kunststoffe | Year: 2014

There is a need to generate fatigue data to demonstrate the long term durability of polymers for use in oil and gas applications. Fatigue testing is specified in standards such as ISO 13628-16 / API 17L1 (specification for flexible pipe ancillary equipment), but no prescribed test method is identified. The generation of long-term data is particularly important for polymeric materials as their properties are not only time and temperature dependent but can be significantly affected by the fluids they come into contact with. This paper discusses the different models used for the prediction of fatigue life in rubber and plastic materials and includes an overview of both crack nucleation and crack growth test approaches. The commonly used international standard methods for rubber and plastic materials are also identified for reference. The standard methods are generally limited to tests under laboratory conditions and therefore custom material or product tests are often required to meet business needs. Since the early 1980s, Smithers Rapra has been generating fatigue data for other industries and offers solutions for providing engineering data for the prediction of lifetime in the operating environment. A test methodology for fatigue tests under fixed load or displacement is described which can be used in either tension or flexure. The design of the test fixture enables it to be immersed into the test environment under controlled temperature conditions. With the expected demand in the future for higher operating temperatures and pressures, test equipment and methods continually need to be developed to enable accelerated life predictions to be carried out. Source


Hulme A.,Smithers Rapra | Speake S.,Smithers Rapra | Cooper J.,Smithers Rapra
Gummi, Fasern, Kunststoffe | Year: 2014

As the service conditions in the oil and gas industry become increasingly more demanding, there is a greater need to demonstrate that the materials selected are fit for service. This is particularly important for polymeric materials as their properties are time and temperature dependent and can be significantly affected by the fluids they come into contact with. To predict life, accelerated laboratory tests can be carried out based on the service conditions the component will experience. In all cases increased temperatures are used to accelerate the tests. A summary of the different approaches which can be used will be presented along with the factors which need to be considered when designing accelerated test programs. A major concern which is often expressed is the validity of the life prediction model. It should be recognized that relatively simple material tests can not possibly replicate the complexity of some product applications. This paper compares the life predictions from accelerated tests with actual long-term test data. The comparison will be made for both the Arrhenius rate approach and time-temperature-superposition. Sources will include the Smithers Rapra 40-year natural ageing study and in-house test data. Source

Discover hidden collaborations