PEEK plastic for sliding steam valve

John, I wonder how much additional information you provided in your "bearing grade" PEEK request to Davis Plastics.
For example did you specifiy for it was for reciprocal motion, not rotary - in the presence of hot saturated steam - running over stainless steel with cut-outs? If not, then you might need to be cautious about their recommendation. After all. Davis Plastics are primarily stockists.

As I wrote before, it does require quite some online research comparing the properties of different HPPs for our 'peculiar' model engineering uses. The PEEK grade "CA30" did seem to me to be preferable for steam valves in our applications. The "carbon loaded PTFE" (graphite or carbon fibre?) Duncan refers to exhibits many attractive properties but it's linear expansion is a negative factor at twice that of PEEK CA30, although it may be prefectly servicable for slide valves with lower temperature steam. (My use was in piston valves in the presence of superheated steam at 180psi).

By the way ~ did you see from Davis' website section "Hobbyists" that they have a special Ebay area of small pieces at reduced prices?
**LINK**

Hi Fowlers, this is the text of the email that I sent to them:

"

Dear Sirs,

I have been advised that you may be able to supply PEEK based materials in small quantities. My application is a small sliding valve for superheated steam. The part will slide on a flat surface with steam ports to allow steam in and out depending on the valve position. The matting flat surface will be stainless steel 303 or 304 grade. Dimensional stability is important but not critical because it's a flat sliding valve after all that can be designed with enough tolerances.

I am particularly looking for a reinforced bearing grade PEEK with low friction and small wear of both the plastic and the matting surface, such as KETRON PEEK-HPV, or VICTREX PEEK 450FC30. These grades are reinforced with carbon fibre and contain graphite and PTFE lubricants.

I have looked at your online store site (shopforplastic) and your ebay store, but I did not find the specific PEEK grade that I require available.

However, I found that the PEEK-HPV material is listed on your davis-plastics site. So I wonder if I can place an order by email.

Ideally, I would purchase a 20 mm diameter rod with 200 or 300 mm length, or a minimal quantity of sheet with at least 8mm thickness.

Are you able to supply this?

Thank you very much.

Kind Regards,

"

Edited By John Lluch on 28/11/2017 08:45:33

John ~ apologies, you'd clearly covered everything; it's well past time to withdraw back into my shell.

No need for apologise, you have been very helpful. I just hope Davis Plastics will eventually reply with a positive answer. I eventually found a local supplier that has the "bearing grade" PEEK that I would like to try, but they ask me to buy a full length rod, which has a prohibitive price. I will let you all know what's the reply from Davis Plastics.