Gasket material for steam engine

[david newman 9Participant @davidnewman9]

Just completed a stationary steam engine, it runs fine but there is a weep coming from the steam chest, bubbles appearing. I have used brown paper for the gaskets (paper bag) this has sealed the cylinder covers OK . Any advice ? Don’t want to use silicone etc as it would be hard to get it apart if needed. David

[david newman 9Participant @davidnewman9]

[JasonBModerator @jasonb]

Paper bags can be a bit thin try brown wrapping paper and lightly oil it before use.

 

You can also by proper steam jointing gasket paper from most of the ME suppliers though this is a bit thicker approx 1/64″ so you need to make allowance for this during construction.

 

If you use a proper gasget silicon you should not have a problem getting the bits apart, pop down to your local Halfords and get a small tube.

 

J

[Steve WithnellParticipant @stevewithnell34426]

David,

 

I have some of the real stuff from Stuart, how much do you need?

 

Happy to stick you some in the post

 

Steve

[BogstandardParticipant @bogstandard]

For many years now, I have been using 0.005″ PTFE untreated sheet for gaskets (that is plain faced, not etched), and never had any trouble with it.

It is fully reusable, unlike normal paper gasket and I have even used it (0.015″) for head gaskets on i/c engines.

 

I wouldn’t trust it though with very high pressure superheated steam, it might be getting towards it’s failure point.

 

 

John

[david newman 9Participant @davidnewman9]

Posted by Steve Withnell on 13/06/2011 21:05:44:

David,

 

I have some of the real stuff from Stuart, how much do you need?

 

Happy to stick you some in the post

 

Steve

Steve you have PM. David

[mansel jonesParticipant @manseljones75785]

Can some one please let me know where to buy a sheet of 0.005" PTFE from?

Thank you

Mansel

[David Clark 13Participant @davidclark13]

EBay

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Always worth checking that you don't have a simple leakpath between portface and steam chest/cover . Most common causes are surface(s) not flat , raised burrs and deep scratches .

Not usually nescessary on little engines but workmen erecting full size engines often took great care to make mating surfaces flat on flat – sometimes even to the point of sraping them in .

[mansel jonesParticipant @manseljones75785]

I am currently building an "0" gauge 0-6-0 tank locomotive "Mollyette" by L.B.S.C. Could anybody please tell me how the Lubricator is connected to the Steam Chest. Also the width clearance between the piston slot and the piston "O" ring

[FMESParticipant @fmes]

I've always used Hylomar Blue (or SQ32M) for steam joints and never had a problem, rarely use a gasket.

Just apply sparingly to both surfaces of the joint, allow to become tacky and assemble.

As the joint is incredibly thin there is no problem with disassembly.

Lofty

[maurice bennieParticipant @mauricebennie99556]

HI all "Lakeland" cookery shop sell a kind of teflon thin sheet for lining baking trays.

maybe you have some in the kitchen I never said that .

maurice

[John Stevenson 1Participant @johnstevenson1]

Lasers are ace for doing gaskets

That hole in the centre of the ventruri support is 1mm and the hole near the edge is 1/2mm.

These are for vacuum valves and you cannot use any typle of sealant because of contamination.

[Speedy Builder5Participant @speedybuilder5]

More detail on laser cutting please – could one 'butcher' an inkjet printer some how, and what / where would one get a laser from ?

Bob

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Mansel ,

The design of Mollyette seems to have varied a bit over the years but on mine the lubricator attaches by means of a little two bolt flange to front end of valve chest . Awkward to attach after cylinders are in frames so pre-fixing advised .

Mollyette would benefit from some upgrading – in particular by the fitting of proper sprung drop out axleboxes .

Regarding grooves for O rings there are proper design rules but on an engine like Mollyette with little power to spare I would use a bit of trial and error so as to get the O ring sealing but sliding easily in bore at same time . Try groove width of 1.25 times O ring diameter for starters and progressively make groove deeper until O ring is only just nipped between piston and bore .

Regards ,

MikeW

Edited By MICHAEL WILLIAMS on 24/07/2013 10:16:15

[Paul LousickParticipant @paullousick59116]

In Oz for full size size engines we use a graphite impregnated sealant. One of the popular brands is "Dicksons". Probably made in the UK.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Loctite plastic gasket works quite well at ordinary steam temperatures .

Perhaps don't forget that many model and full size engines have been sealed successfully for many years without using any gaskets at all – just properly fitted parts and sometimes with a smear of red lead or putty thinned with oil .

MikeW

[Gordon WParticipant @gordonw]

A string "fence" round the outside of the fixing bolts, a common fix. On model engine sizes cotton would do. A bodge, I know , but works.

[mansel jonesParticipant @manseljones75785]

Hi Michael

Thank you for your very helpful posting. The Mollyette drawing is not good. If possible can you please explain the steam pipe fittings from the lubricator to the steam chest.

Mansel

[mansel jonesParticipant @manseljones75785]

Hi Michael

Thank you for your very helpful posting. The Mollyette drawing is not good. If possible can you please explain the steam pipe fittings from the lubricator to the steam chest.

Mansel

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Mansel ,

I've put a sketch showing arrangement of lubricator and steam feed in your pm's .

Union connection shown may have to be angled slightly to clear axle .

Last part of steam passageway into oil tank is specified as being a ' fine hole ' – might be better to contrive a simple needle valve instead .

Mollyette is a tricky engine to get to run properly but very pleasing when you do .

Ask any further questions you wish .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 26/07/2013 23:10:50

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