We use Peek exclusively in PSVs above 1200-PSI, and achieve API-527 with it. High attention to detail in the mating surface with the valve is critical. Peek machines like a soft metal, and with force (of the valve action), seals like rubber, plus no closure deformation (critical when you have...
With such a low working pressure defined, why not use a simple spring-plunger piston with seal (very much like the commercial PSVs you have in mind?) A simple sealing seat, a piston of sufficient area that you don't get into a bind looking for a spring with a tremendously low rate, and an...
