On Sun, 21 Mar 2021 14:32:45 -0700 (PDT), trader_4
wrote:

On Sunday, March 21, 2021 at 5:03:50 PM UTC-4, wrote:
On Sunday, March 21, 2021 at 2:29:50 PM UTC-5, trader_4 wrote:
I had to replace the steam valve in my Saeco espresso machine. This is very
strange. The new one is the right one, identical to the old one. But both
just have a straight nipple about 3/16 that screws on to a brass 90 deg fitting
that in turn screws into the boiler. But the nipple does not have tapered
pipe threads, just straight threads. Further, it has a lock nut on it
because it has to be screwed
in just enough so that the valve shaft lines up with a hole in the cabinet.
So it goes inabout 3/8" or so, whereupon the shaft is where it needs
to be and then you tighten up the lock nut.
So this screwy fitting isn't made to bottom out, there is no place for a
seal inside and it doesn't have tapered threads to seal.
The parts diagram doesn't show anything used there either.
And it doesn't screw in particularly tight either. So much for great
Italian engineering.

So, what to seal this with so that it won't leak under 225F and 175 PSI?
I tried teflon tape, it doesn't work, nor does pipe dope. Couldn't tell if
something was on there from before, but looks like there was and there
must have been. So what to use to seal it? Something non-toxic
would be a good idea too.
Would something here work? It sounds like a bolt going into an engine block.

It is kind of like a fine thread bolt, except it's a nipple with water/steam going
through it and there is no head, just a lock nut.


https://www.permatex.com

I have some permatex non-hardening in the garage and was even thinking of
using it, but it's not food safe. I don't see that they have anything food safe
either. I don't think it's really that big a deal, any contact between whatever
is there and the water would be very minimal. But food safe would be better.
I think I have it solved, thanks to good old Ebay.

https://www.ebay.com/itm/RTV-6500-RE...cAAOSwOWpcuH2W


That listing doesn't say it's food safe, but you can see it on the label and other
sellers have it listed as food safe. Food safe and high temp, hope it works.
They must have used something other than silicone when it was made 25 years
ago because you usually have remnants of silicone left and you know it was
there. Seems like there was something on there, but more solid, like threadlocker
kind of stuff maybe. For $6, this is worth a try. Next problem, I broke a part in
the portafilter, have to get that from Bulgaria, $20. Sigh.....

Why not treat it like any other straight thread fitting and put a
gasket under the lock nut. That is what Yamaha does on their
outboards. An O ring that is tight on the threads should work.