Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Today I had lots o free time and decided to get the courage to take apart half of the plant and add a very much needed S/V.    Before you raise eyebrows yes it’s a Stuart SV.  But, I have it popping off at 25PSI.  Adjusting the damn spring seemed to be more work than redoing the piping.

When I first put the plant together I didn’t consider these things, such as a Union joint in the steam line which makes disassembly radther tricky especially for something like this. 

But I managed to do it. Prior, I was just never letting it get above 30psi, by tooting the whistle and running a balanced engine but it’s certainly not the safest thing.. so now I can run it and not worry as much about pressure because it’ll pop off if it gets too high.

Biggest issue is once it pops off I have trouble with it closing again. I’m trying different springs and things. Tried a Jensen spring but it just doesn’t have enough tension to snap it shut.

All in all, still works.



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A safety valve is well.....safe ! I guess none of us noticed that egregious lapse in judgement or we would have advised you to get one. Glad you have one now though.😊

Charlie pointed it out and I realized it truly was dangerous not having one.  A boiler explosion with hot shrapnel and scalding steam water would be catastrophic to me or anyone for that matter.

Glad I added one. Was quite a task, to say the least.   I think I can say this plant is finally complete.  lol.

Still not safe being mounted after the globe valve…

I leave that valve fully open.

You’re still restricting flow to the safety or someone could close it accidentally

True.   I’d have to dismantle it again to remove that valve. 

When you dismantle it again to correct the globe valve position being before the safety valve, you might want to consider installing a union joint or three to ease future maintenance and modifications.  ;c)

This is a good idea.  I put one on the water pump which made removal very easy. Putting a union joint at the steam pipe on top of the boiler before the SV, and one near the end of the steam line would definately be a good thing.   Measurements will be tricky to have it match up to what is current, though.

You've probably worked this out yourself, but for putting in PMR pipework I use a small (around 5" I think they are) Channellock pair of water pump pliers
and some THICK leather (has to be THICK or the Channellock teeth will come through) and it grips well and won't damage the brass.

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Vice Grips work too, if you use the leather pad as Jim describes and adjust the "clamp" pressure just right.