Author Topic: Treatment of steam valve surfaces and gaskets  (Read 942 times)

Offline Mcgyver

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Treatment of steam valve surfaces and gaskets
« on: June 22, 2018, 03:00:39 PM »
Hi,

i'm putting the push on to finish a Stuart Triple Expansion engine.  I've built some steam engines before as well as hot air and a hit and miss but I've not really had it squared away how best to prepared the steam valve mating surfaces.  Usually its so enjoyable finally get to bolt the darn thing together I can't wait....and then about all I have interest in is placing on a shelf after a few moments with the air gun. (it is the journey not the destination)

Anyway, more discipline on the triple.  Would you grind or lap the cylinder surface, the valve? 

While we're on keeping things steam tight, what about gaskets?  Necessary throughout?  paper soaked oil?  do you adjust part dimensions to account for gasket thickness (it can add up on an assembly like the triple)?

thanks for any and all advice
« Last Edit: June 22, 2018, 03:25:50 PM by Mcgyver »

Offline crueby

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Re: Treatment of steam valve surfaces and gaskets
« Reply #1 on: June 22, 2018, 03:14:30 PM »
I like to lap the surfaces of a cylinder and slide valve setup, but thats an easy choice since I dont have a setup to grind or hone them.For gaskets, I've had good luck with the paper based auto gasket material, also have used the silicone or whatever it is goop, though that does not allow for disassembly/reassembly like the paper does. Main thing that I have forgotten sometimes is to make the studs long enough to handle the extra thickness of the gaskets.

Offline Jasonb

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Re: Treatment of steam valve surfaces and gaskets
« Reply #2 on: June 22, 2018, 04:12:43 PM »
I usually just rub the valve face onto some 1000g wet and dry laid onto my marking out surface, don't usually bother with the port face but suppose it depends on teh finish you get, I like to use a new smallish cutter and do overlapping passes for a nice flat surface.

I use a liquid gasket, no cutting and no need to take thickness into account.

Online kvom

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Re: Treatment of steam valve surfaces and gaskets
« Reply #3 on: June 22, 2018, 04:36:38 PM »
I have tried a lot of different gaskets, including paper gasket sheet, liquids, teflon sheet, and nothing at all.  I usually go with the 1/32" teflon sheet as first choice these days.  Many have advised oiled $1 bills as they are made from cotton.  For slide valves I've generally been happy with milled surfaces on the ports and 1000 grit paper on the valve. 

Offline crueby

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Re: Treatment of steam valve surfaces and gaskets
« Reply #4 on: June 22, 2018, 05:47:19 PM »
I have tried a lot of different gaskets, including paper gasket sheet, liquids, teflon sheet, and nothing at all.  I usually go with the 1/32" teflon sheet as first choice these days.  Many have advised oiled $1 bills as they are made from cotton.  For slide valves I've generally been happy with milled surfaces on the ports and 1000 grit paper on the valve.
Never heard of that one. Where did you get the teflon sheet, are there multiple types? Does it compress much?

Offline Ramon

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Re: Treatment of steam valve surfaces and gaskets
« Reply #5 on: June 22, 2018, 06:48:35 PM »
I would concur with all above - lapping the valve as Jason suggests then lapping the it to it's respective mating surface.

I've used oiled thin brown paper or oiled 80gms copier paper in the past which makes for very good gaskets but as you say all gaskets have a thickness and will add to things. I recently tried 'Hylomar' which allegedly gives a very good seal that can be broken apart easily. Cant' vouch for that as nothing been stripped down as yet but the sealing was perfect. Only one problem I found with it is that any residue that seeps out is very sticky and difficult to get rid off even with solvent. I tried several, including petrol, white spirit meths etc but done would dissolve it. Cellulose (Lacquer) based thinner could not be used due to parts being painted. Personally I wouldn't use it a again and don't recommend it for the cleaning problems alone - I'll go back to a thin smear of silicone sealant - for air only display models that is.

Regards - Tug
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Offline Admiral_dk

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Re: Treatment of steam valve surfaces and gaskets
« Reply #6 on: June 22, 2018, 08:53:36 PM »
I've used liquid sealing for some 40 years on my motorcycles. It used to be Red Hermetite for the first many years, but have tried many other types since including silicon based - all with great success  :ThumbsUp:  You can use the totally clear stuff in order for it to be non noticeable, but it can be a pain to see if you have done the correct layer when applying it too ....

BUT there are a few things to avoid, like be careful that it don't end up blocking any oil passages or end up against any moving surfaces. Don't apply too much (I still fall for this one in order to feel very sure it will be totally oil tight) and forget about removing it by ANY other means than mechanically - you can rub it off with your fingers or a piece of cloth and cleaning mating surfaces again before reassembly is done the same way !!!!

And I agree with all above comments on how to get perfect sealing and used most off them too .

Online Tennessee Whiskey

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Re: Treatment of steam valve surfaces and gaskets
« Reply #7 on: June 22, 2018, 09:31:46 PM »
I use an oiled brown stock ďgrocery bagĒ . Now when I say oiled, I donít mean that I soak it in oil, just; rub it with my really oily fingers. Iíve seen Dad and grandpa stack several together to use for thermostat housings and such. Really, if the mating surfaces are true, donít take much.

Cletus

Offline crueby

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Re: Treatment of steam valve surfaces and gaskets
« Reply #8 on: June 22, 2018, 09:38:30 PM »
I use an oiled brown stock ďgrocery bagĒ . Now when I say oiled, I donít mean that I soak it in oil, just; rub it with my really oily fingers. Iíve seen Dad and grandpa stack several together to use for thermostat housings and such. Really, if the mating surfaces are true, donít take much.

Cletus
I've tried that a couple of times, the bags they use here must be different, they always wept through, like they had too many large pores across the inside.

Online b.lindsey

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Re: Treatment of steam valve surfaces and gaskets
« Reply #9 on: June 22, 2018, 09:52:13 PM »
For larger engines I use auto gasket material about .020" thick. For smaller jobs like the Tiny IC and Elmer's sized engines, copy paper or brown kcraft paper works well and is more to scale.

Bill

Online Gas_mantle

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Re: Treatment of steam valve surfaces and gaskets
« Reply #10 on: June 22, 2018, 11:01:32 PM »
I cant really offer any advice on lapping surfaces etc but for gasket material on the last few engines I built I have used this stuff :-

https://www.ebay.co.uk/itm/GASKET-PAPER-MATERIAL-OIL-WATER-RESISTANT-FLEXOID-BRAND-5-X-A4-SHEETS/141462465314?hash=item20efd1eb22:g:LRsAAMXQQQhRe6Ey

I've yet to make an IC engine but the gasket paper seems to work fine for live steam.

When I made my first little steam engine I did try a liquid gasket compound (not sure what it was but it came in a squeezy tube and looked like black toothpaste) I found it leaked under steam and had no benefit over cheaper and more convenient paper gaskets.

Give the paper a good soaking of oil then tighten then retaining nuts with a scaffolding pole on't end of yer spanner an nowt will leak  ;)

Online b.lindsey

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Re: Treatment of steam valve surfaces and gaskets
« Reply #11 on: June 23, 2018, 12:19:25 AM »
Just had a thought. Has anyone ever tried parchment paper? It pretty thick as paper goes and heat resistant. Easy enough to find at the grocery too.

Bill

Offline steam guy willy

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Re: Treatment of steam valve surfaces and gaskets
« Reply #12 on: June 23, 2018, 01:26:45 AM »
Hi Chaps ,.....noticed this on the Flexoid site... so do they still use asbestos ?? or do they mean they do not use asbestos at all anyway ? !!

Willy
« Last Edit: June 23, 2018, 01:29:49 AM by steam guy willy »

Offline derekwarner_decoy

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Re: Treatment of steam valve surfaces and gaskets
« Reply #13 on: June 23, 2018, 05:59:22 AM »
Hullo Willy.......I think we have all seen the videos of BMW or an Mercedes robotic armed, computer controlled with liquid sealant being applied during the assembly of their product engines

We as humans do not necessarily have a true understanding of the correct amount ...& location of such sealants during the assembly of our engines

I am sure being over zealous to ensure adequate sealant is supplied, so we place far too much GOOP between the mating parts

 :Director: ..so what happens to the internal surplus material into steam passages?

Thick brown paper ...or the Flexoid material ....pre cut & soaked in light oil overnight will be fine gaskets for our pressures to ...say 4 Bar :ThumbsUp:

Derek
« Last Edit: June 23, 2018, 01:54:47 PM by derekwarner_decoy »
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