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Victrex Polymer Replaces PTFE in Electrode Insulator Connector

10 January 2012

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 VictrexST high performance polymer to improve durability, reliability and increase the overall lifetime of the connectors.

According to Victrex, 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 which 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. 

Escontrol tested a number of materials. "We tested polyimide (PI) and thermoplastic polyimide (TPI), but these had a much shorter life (1 to 2 weeks) due to hydrolysis caused by exposure to superheated steam,” said Jaime Denicol, Technical Director at Escontrol. “By switching to VICTREX ST polymer, the module’s expected lifetime is now more than three years.” 

Victrex say that 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.” It was developed to meet the most demanding environments requiring high temperature performance and mechanical performance associated with excellent dimensional stability.

“Using Victrex ST polymer for the connectors has reduced the field complaints by customers and strengthened our product reliability," explained Denicol. The most important benefit of using Victrex ST polymer has been the increased durability of the instrumentation module whose previous lifetime, when PTFE was used, was only a few months. “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," said Denicol.