You might try X-Pando. It worked for a seriously oddball thread on my lever project when nothing else would. It also has absolutely no odor, no nasty chemicals, NFS/FDA approval, and is rated for something like 1000 psi. 15 psi of steam is nothing. I think it isn't that popular because it comes in a powder that you mix.

Great suggestion, Paul, and the price is right too. I just ordered some from an e-Bay seller under $20 shipped.

i don't know the process of brass corrosion due too superheated water. but i noticed that leaks of superheated water apparently leach out part of the alloy and the fittings become brittle respectively the threads sort of disolve. it happened on my orione several times. looked similar to your green 'stuff'.

Ugh! How did you fix that? And do you know if running too much distilled water may start causing that deterioration?

Added: This thread is interesting because it highlights the potential for dionized (distilled) water to promote electrolysis where different metals contact each other. I've been using mostly distilled water in my machine to avoid scale, but maybe that's too little of a good thing.

Will distilled water harm my Elektra Semiautomatica?

i replaced the fittings and made sure they are not leaking. did a pressure test with pressurized air and soap water.
the corrosion is de-zincification. you can look it up per google e.g.http://corrosion-doctors.org/Forms-sele ... -valve.htm. someone mentioned it here a while ago.

personally i'm not a fan of the conventional espresso machine fittings at all. i would prefer npt and flare fittings.

Thanks, Oliver. So this is a potentially repeating problem and I'm dealing with an adapter mating to the T fitting and fitting a standard espresso machine manometer knuckle. At that joint I think I'll disconnect, clean it up and fasten the adaptor into the T fitting with a copious amount of thread locker and monitor it. Hopefully the thread locker will prevent further de-zincing. I think I'll try that approach on the other end too if inspection shows the threads aren't too badly deteriorated since otherwise I would have to sweat a new connection and probably change the pipe itself. Even though it's brass on brass the difficulty may be having those thread surfaces exposed. Then I'd better test my water mixture and make sure it's not slightly acid or alkaline.

I went in today, took apart, inspected and cleaned up those fittings and reconnected them. There was very little internal or thread corrosion and nothing needed replacement. I added food-safe Loctite to the brass adaptor fitting where it threads into chrome-plated brass. I chose Loctite because the X-Pando may be more porous and slightly acidic/alkaline water in high heat with limited circulation and a porous coating may make this area more vulnerable to de-zincing. Otherwise I wrapped all connections in PTFE tape and tightened them down, being careful not to overtighten. My initial guess is I need water with more mineral content and can't run straight distilled or anything close to that. I'm letting the Loctite set overnight and will pressure test in the morning and if all goes well will reassemble and welcome the Prestina back to my kitchen.

The PSTAT connections were pretty good when tested. One at the bottom of the T fitting leaked until I tightened it. But the water tap needed to be tightened hard to stop dripping and then it turned a bit. The complication here is it has a dipper tube inside the boiler that must be pointed down and the tube is too long to turn until it's completely tight. Finally I realized the wisdom of Dave's suggestion to use JB Weld. The trick was to use a tiny bit so it can be easy ground out with a rotary tool in order to service the gaskets. Since it's a little loose once the JB Weld sets I'll add thread sealant around the base of the taps. Here you can see I used only a little JB Weld and only on one surface.

Late to the party here, but the color is amazing, and I hope you have years and years of enjoyment. Now, if you only lived in the Nashville area

Thank you, Rob.

Well, this morning I went out to see if the JB Weld had secured the water tap in place. No. It wiggles now. This means I'll need to pursue a larger project, unfortunately. I'll empty the boiler and remove the back of it to get at where the taps fasten to the front plate and get these firmly fixed and sealed in a way they no longer turn. I'm thinking a generous helping of food-safe Loctite thread locker in the mounting holes will do the trick. More posts soon. Then I'll integrate this material on securing the taps into that section in the restoration. At least there's a really nice Elektra Microcasa a Leva on an appliance timer ready for my morning espresso...