Polymer replaces PTFE
14 February 2012
Victrex ST polymer replaces PTFE in an electrode insulator connector for high-pressure vessels.
When Escontrol, a Brazilian manufacturer of control and electronic instrumentation, needed to replace the electrode insulator connectors in its thermal equipment instrumentation for high-pressure vessels, it chose Victrex ST high performance polymer to improve durability, reliability and increase the overall lifetime of the connectors.
The instrumentation, used in industrial, medical, food and petrochemical industries, is essential for the proper operation of fluid phase power generation equipment. Originally, the connectors were made with polytetrafluoroethylene (PTFE) but they exhibited a number of durability issues that required the need for interventions and unscheduled downtime for maintenance.
Escontrol concluded that PTFE had insufficient strength to withstand the combination of high pressures and high temperatures in which the connectors are subjected. This caused a high susceptibility to electrical leakage and the consequent risk of short-circuiting the system.
Looking for a higher performing solution, Escontrol tested a number of materials. "We tested polyimide (PI) and thermoplastic polyimide (TPI), but these had a much shorter life – one to two weeks – due to hydrolysis caused by exposure to superheated steam,” said Jaime Denicol, Technical Director at Escontrol. “By switching to Victrez ST polymer, the module’s expected lifetime is now more than three years.”
Because the connectors are exposed to temperatures in excess of 200°C (392°F) and pressures in excess of 70 bar (1,015 psi), material requirements demanded a combination of properties including superior electrical and thermal insulation, excellent hydrolysis, chemical and temperature resistance, low water absorption, good dimensional stability and mechanical strength.
According to Ana Paula Celiberto, High Performance Shapes Manager of Ensinger, the moulder of the connectors: “When Escontrol approached us about moulding the connectors, we considered the operating conditions of these components, and chose Victrex ST polymer due to its unique combination of properties.”
Denicol added: “Using Victrex ST polymer for the connectors has reduced the field complaints by customers and strengthened our product reliability. Not only does Victrex ST polymer provide excellent electrical isolation, which prevents failure caused by other problems in other components of the instrumentation, it has downplayed the risks of short-circuiting the system and greatly increased safety."
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