Durability of Nylon 11 coated disc (butterfly valve)
Durability of Nylon 11 coated disc (butterfly valve)
(OP)
I am considering accepting a butterfly valve that has a nylon 11 coated disc in a hydronic piping specification (for commercial/institutional HVAC applications).
Currently, our specification calls for a bronze disc and I am considering expanding that to include a nylon coated disc.
My question to the forum is: Has anyone experienced the problem of the nylon coating breaking off, requiring valve replacement and significant damage to the hyrdronic system?
This valve will be in a hydronic system, so it may see glycol or water treatment chemicals.
Thank you and regards,
Dave
Currently, our specification calls for a bronze disc and I am considering expanding that to include a nylon coated disc.
My question to the forum is: Has anyone experienced the problem of the nylon coating breaking off, requiring valve replacement and significant damage to the hyrdronic system?
This valve will be in a hydronic system, so it may see glycol or water treatment chemicals.
Thank you and regards,
Dave





RE: Durability of Nylon 11 coated disc (butterfly valve)
I have myself no relevant experience for nylon coated valves, and will not comment on this directly, but will suggest that you 'sharpen' your quality description and research before you accept this new valve:
1. producer to give relevant positive references from long-term installations you can check yourself.
2. Exact description of coating and construction. As known 'nylon' was originally a trade-name for a DuPont patented polymer, and newer variations by others are different , but behaving about the same, but some variations / similar constructions may prove better (??? delrin ??? is this a nylon? or (cheaper? PTFE?)
3. Coating thickness, stem material, stem cover, bearing, disc (metal) material, mechanical details and strength together with exact chemical conditions during lifetime for media exposed parts will influence on cost/ lifetime considerations.
3. If this offer has come 'out of the blue' ask your normal supplier and at least one other competitor for competing offers, ask all to include references,expected lifetime and arguments for the construction, and also to include suggestions for other materials than you original to best suit your wishes (hygienic, lifetime, price, or price over lifetime, etc. etc...)
RE: Durability of Nylon 11 coated disc (butterfly valve)
Thank you for the advice.
RE: Durability of Nylon 11 coated disc (butterfly valve)
Also important is the fact that once the coating is compromised you will have an exposed metal substrate. Most manufacturers that I am familiar with (including my company) use Dutile Iron as a substrate. Exposed ductile iron may, or may not, be a problem in your application. Its just a call you would have to make.
RE: Durability of Nylon 11 coated disc (butterfly valve)
Your comment follows this line of thinking.
Thanks,
Dave
RE: Durability of Nylon 11 coated disc (butterfly valve)
Yes indeed. No coating can claim to be free from holidays, or to remain bonded forever.
What is the force driving you to consider other options besides the bronze disc?
-Vrf
RE: Durability of Nylon 11 coated disc (butterfly valve)
If you're concerned about chip fragments and it's for long term usage, I would recommend you keep to your bronze disc specification.