PK002 is a (natural) high-performance thermoplastic commonly referred to as PEEK.

The material has excellent physical and chemical properties to serve a wide range of applications at high temperature.

PK002 has good tribological characteristics and is recommended for precision parts, where tight tolerances are required.

JST chose its PK002: Virgin PEEK for the back-up ring material. PEEK is a much higher modulus or stiffer material than PTFE. Consequently, it is much more difficult to extrude.

While PEEK has a high upper-temperature limit, it can resist 260℃ for a long time and 300℃ for a short time, it also retains the non-galling and flexibility attributes of plastic. There’s no risk of damaging the hardware.

The wedge shape of the back-up ring also contributes to the increased pressure handling of the seal. The wedge is angled so that as pressure forces the seal to the back of the gland, the heel rides up on the back-up ring keeping it away from the extrusion gap.

How does it perform

With higher filled jacket material and the back-up ring effectively minimizing the extrusion gap, the seals passed the 15,000 psi at 300°F worse-case sealing test.

The customer could safely market their instrumentation as prepared to handle any drilling situation in any location.

This was all done without any changes to the hardware, saving the customer from an extremely costly redesign and rework. It is also important to note, JST achieved the higher-pressure rating without compromising the sealing performance at the lower operating temperatures.