High pressure valve seals

[cannondale]

I have a high pressure fluids application. The valve is a sliding spool type with the pressure acting inside a blind hole in the spool with a side port. When the pressure is reached the spool moves and the port lines up with another in the body and hence flow path is achieved. I'm trying to seal the spool and the body. I'm using a yellow metal liner for wear and to allow a slightly softer interface between the spool (Inconol) and the body (EN19T). Fluid will be oil/water (could be seawater) with 300micron particles, approx. 1-1.4SG, solids content approx. 20%, 0-30deg C, hydrocarbon service, and the possibility of H2S could be advantageous but not necessary for the majority of applications.
I've had differing advice, and my gut feeling is wear rings and wiper seals. I can change the geometry accordingly, but don't have lots of space in the stroke to allow more than approx. 10mm.
The spool must be able to re-seal after operation and I'm wanting more than 100 actuations really. Any advice on seal applications (not the sea living mammals ). Pressure is likely up to 690barg, assuming I need to look at specials due to size and make up.
I've contacted a few companies but haven't managed to settle on a similar design or material yet. Both want to design a special, but they are different. Anyone with advice of specifying materials and seal designs?

 

[gerhardl]

I have a bit difficulty with visulizing the valve and movement geometry here. Sketch? Approx. size?

 

[cannondale]

I did try but cant see how I add a document as I don't have a web location to put as the url? Do I have to register a cloud (google etc) account and load to there and then post the link?

 

[gerhardl]

Use the TGML bar on top of answering space (above row for text format).

 

[mgh70]

I would look into Hytrel, spring energized lip seals, with a back up ring for extrusion. Though you won't want much extrusion on your back up ring, so consider that.

Hytrel is one of the better materials you are going to find with the seal-ability at and the abrasion resistance you will need since you will have a dynamic seal plus dirty fluid. Plus a lot of people have tooling for larger diameters for Hytrel, I don't know what diameters you're looking at. I am also not sure what its immersion tests look like in saline conditions, though I'm sure you can find all the data you need on the Dupont website.

Let me know what you think, cheers.

-M