Rust, CI, Localised corrosion - gaskets ?

I am building a Stuart Victoria Stationary engine.

Having completed the cylinder and steam chest about 3 months ago these were stored in a draw. I have just taken them out for final fitting to find that everywhere which has gaskets is rusted, chest and cylinder endplates, but only where the gasket touches. The bore and all outer surfaces are all rust free.

Its as though a chemical in the gaskets is causing the rusting.

Any ideas on what this problem is? I can't believe Stuart would knowingly supply incompatible gasket materials.

Any Advice much appreciated.

Would post pictures but I can't seem to do it .. .

Best regards

picclock

Hi Martin,

Welcome to the forum. If the gasket material is porous it may have had some humidity in it when you mounted the gasket, if you used paper as gasket material some papers are slightly acidic. When I use paper gaskets I always impregnate the gasket with oil.

Thor

(How to post photos here)

Edited By Thor 🇳🇴 on 26/08/2022 17:45:07

As you can see this is a serious attack of the brown stuff, not just a bit of damp. All the surfaces were good before storing, and the nuts holding the chests and cylinder ends were tight. That should have excluded any oxygen. The gaskets on the cylinder ends were stuck to the surface. No sealant was used, as I knew it would come apart again before final assembly. I would have been better off leaving it in the garden shed .. .

There was no obvious dampness in the gaskets, which were used straight from the kit box.

I intend to replace them with Flexoid gasket material, which I have used before, unless anyone can think of a reason not to.

I have never had rusting like this on such a short timescale with such severity.

Bit of a puzzle really

Best Regards

picclock

Edited By Martin Dare on 26/08/2022 18:44:38

Hello Martin,

As Thor says it may have been humidity but already in the material as you assembled it perhaps?. It certainly does seem strange as all other areas are free from rust so can only have come from the material and/or conditions on assembly I would have thought.

Like him I make all gaskets from thick copier paper (90-100gms) and soak it in (slideway) oil on assembly. Not always absolutely seal proof if running on steam of a decent pressure but perfectly fine for air.

That said I ran my first engine, a Twin Vic, at displays on steam for several years with such gasket material - pressure about 40 psi - without any issues save on the second outing. I had not lubricated the cylinders enough after running at the first display. Getting it out for the next the (gunmetal) pistons were solid, rust having formed in the bore either side of them. It required a complete strip down but fortunately the bores were not damaged. After that my clean down procedure after display was to run Steam Oil through on air until it came out of the exhaust. Never had the problem again and something I still do even though I only display on air these days.

Hope that's helpful

Regards Tug

Like the others I would say moisture in the gasket material, and clean unoiled surfaces.! Good Luck. Noel.

It's good to put a smear of grease on either side of a paper gasket. Would probably stop this rust problem and also makes disassembly easier in the future.

As above...

Just to remind folks that, should one wish to avoid the problems of gaskets by using silicone 'gasket goo', it's safer to go for a 'neutral cure' type that doesn't liberate acetic acid as it cures. This evolved acid can cause unprotected nearby surfaces to rust spectacularly.

(I realise that I don't understand the chemistry involved that makes acid fumes cause steel to rust. This acid-fume-induced rusting was used by gunsmiths to colour firearm parts. Can anyone enlighten?)

Hi
Thx for your comments. I will clean up the surfaces and lightly oil them with hydraulic oil. I have made some new gaskets with Flexoid gasket material which I have used before with zero corrosion issues.

It was stored in the same drawer next to the flywheel which is waiting for final bore and keyway. The flywheel surface is highly polished, and though very slightly tanished shows no sign of rust or corrosion.

Its a bit of a puzzle really .. .

Many thanks for your interest and suggestions.

Best Regards

picclock