The Steamboating Forum

Checking a Simpling Valve of the type that is opened by depressing a lever, I noted a hairline crack across the valve which is inset in a bronze (?) shroud and mates with a conventional bronze seat. On investigation, it proved to be some kind of composite material of a terracotta colour that crumbled under pressure and is quite soft. The valve is a home-brew of '80's vintage.
Can anyone suggest what this material is?

Thanks for all answers.

Just a thought since I posted the above; it wouldn't have been an ordinary fibre washer???

Old Steamer wrote:Just a thought since I posted the above; it wouldn't have been an ordinary fibre washer???

Yep.

Make a new seat turned out of Teflon bar for a trouble free repair. Or you may find a replacement washer at the hardware store.

The "terracotta" is likely silicone...

https://www.easternseals.co.uk/sealing- ... e-o-rings/

Also available in sheet.

-CB

CB,
The piece is an actual disc of material and definitely not rubbery.

The more I look at it, the more I think Kelly and my afterthought are correct. I understand the spilling valve was modified mid-80's and has probably never been touched since. That says something about the durability of 20th century fibre washers!

Thanks for taking the trouble to respond.

OS

I'm only guessing, but could your seat material be SRBF? (= Tufnol, = synthetic resin bonded fabric). It would be on its limits at steam temperatures, but it was (and is) easily available, and pleasant to machine, unlike most grades of PTFE, which would stand the temperature better.

By the way, if you do use PTFE as a replacement material, choose the grade carefully: unfilled PTFE will not be at all harmed by steam temperatures, but it would get quite soft, and the soft surface "picks up" any metallic or other dust and debris, which will eventually become a problem. I can't remember the appropriate percentages, but a "medium" glass-filled grade would be better.(too much filler, and I think it would be harder than ideal for a seat).

It doesn't have the grain texture of Tufnol and is very brittle. Taking a bite at it, it has the feeling of a ceramic rather than baked fibre. Is that a clue?

Its about 11/16" diam. and 1/8" thick with a central hole to accommodate a 2 BA retaining stud. (See photo.)

It's a very small piece of kit and the prices I've seen for PTFE are so pricy while leaving me with a large chunk of exotic material collecting dust, I'm trying to think of a more low-tech approach. Unless somebody has an off-cut of glass-filled PTFE they wish to off-load?
OS

Are you sure that your local hardware store doesn't offer replacements? My local True Value has a number of bins of replacement valve discs.

It doesn't have the grain texture of Tufnol and is very brittle. Taking a bite at it, it has the feeling of a ceramic rather than baked fibre. Is that a clue?

They get brittle with use. When new, it would have had a very hard rubber texture. Reciproca's throttle had a "steam" seat. It was exactly that color and was probably a standard composition seat. I looked on the valve maker's websites, but it doesn't look like anyone offers composition seats any more, the Teflon universally taking its place, and no wonder either. Have no fear about using virgin Teflon for valve discs in steam up to 200 PSI, i've been doing it for decades.

Old Steamer wrote:Unless somebody has an off-cut of glass-filled PTFE they wish to off-load?
OS

I have some good quality PTFE from mcmaster carr.You'd have to turn it as it is square. It's not glass-filled, but as Kelley points out it doesn't have to be.

So, yes. I am willing to give you some it what I have will suit...

I have 1"x1" sqaure Ptfe stock.. Actual Teflon brand. Also 6"x6" 1/4" thick sheet.

If you want some just pm me your email or mailing address...

-CB

Kelly,
Having attempted to saw, file and burn the material (all of which it resisted) I'm pretty sure it's ceramic. Given the fact that the whole assembly has been cobbled together, I wouldn't be surprised that somewhere an old valve is missing some of its components.

As the main point is to replace the original with something suitable, I have to thank CB for his kind offer of Teflon. However, it's a long, long way from North-East Ohio, USA to West Lothian, Scotland and I would not want him to go to all the trouble and expense of sending it across the pond. Thank you all the same.

All is not last as a venal friend assures me he has a chunk of the necessary material and being open to liquid bribery will delve into his stocks and, with further bribery, will release it to me. Thus, the situation is saved.

OS