Coating Port Surface and D Valve for lubricity

[JonRiley56]

All,

Is there any value in coating the surface of the d valve and the port surface with graphite or something similar whil I have it apart ? If so, does anyone have product recommendations ?

jon

[Mike Rometer]

A Belgian steam fanatic called Luc Tennested experimented with Teflon coating of valve faces and ports on miniature locomotives, but I don't know any details or results. Luc unfortunately passed away earlier this year. Perhaps a 'net search might turn something up.

[gondolier88]

If the cylinder casting and the valve are good quality SG iron they will self lubricate with the inherent graphite in the iron. Helped along by steam cylinder oil.

Greg

[SailorHarry]

There are a number of interesting and relatively new coatings being applied to high-end automotive engine building. There are ceramic thermal coatings being used to insulate the tops of pistons and other "oil-loving" coatings used on the sides of pistons to retain lubricating oil. I have been thinking of experimenting with the thermal coatings on the inside of steam cylinder ports, cylinder covers, and other non-wear surfaces exposed to steam. Anyone know what I'm talking about?

[87gn@tahoe]

Reviving a thread from the dead...

I'm aware of the automotive coatings mentioned. Jet Hot makes some really nice thermal coatings and
techline makes good coatings for lubricity. There's Cerakote also.

http://www.jet-hot.com/

http://www.techlinecoatings.com/

http://www.cerakotehightemp.com/?gclid= ... 7AodI0EAaw

As for cast iron on cast iron... Here's a picture of the hp valve face on my father's Scripps compound after the use of superheat, and with steam cylinder oil at one drop every 100 revolutions, 180RPM, 150 psi. Non-balanced d-slide valve.

When she was in the water regularly we ran her every evening during the summer for 6 hours at a time. This is after 5 years use.

[fredrosse]

Some in the 7.5 inch railroad locomotives use teflon piston rings without lubrication, probably on piston valve type engines.

[fredrosse]

Of course we all agree with gondolier88, good cast iron and steam oil. That has been proven many times. Spilling experimented with several options and found none successful without lubrication, except for piston valves, tungsten carbide on tungsten carbide. Those engines are rated up to 750F I believe.

[DCSmith]

Do you think Teflon rings would work on larger engines, my steam temp should be below 400 f.?

[Seena]

Hi,
I am associated with http://www.kalpindustries.com
Yes, graphite coating is a good choice for lubricating. It withstands high temperature changes without cracking.

[Lopez Mike]

I really think that this is an area where copying full size practice would pay off. What I mean is using a balanced slide valve.

Not something crude like just an O-ring but done properly with a telescoping insert. There several parts to such a thing but none of them that hard to make from scratch. The resulting valve assembly runs at a uniform temperature (all parts at the same temp as each other even over a wide range) so the fits can be close.

One look at that worn valve face should make a believer out of anyone. Superheat has its drawbacks. Let's hear it for saturated steam. I know. A luddite.