I'm replacing the manometer on my Pavoni PUB. The copper pipes that connect to the original gauge seem to have grease on them - on the fittings connecting to the gauge, and on the fitting connecting to the boiler. I'm assuming I need to put grease on the fittings as well, since I removed it while cleaning and descaling them. What kind will do? I have some Dow 111, will that work?

Hello:

negrocorto wrote: ... pipes that connect to the original gauge seem to have grease ...

Never seen that. Maybe whoever did it before you applied some to smoothen the tightening operation but (as far as I know) it is not standard procedure nor is it needed.

negrocorto wrote: I'm assuming I need to put grease on the fittings ...

Don't.
I wouldn't.
Espresso machine fittings do not need grease, if in good shape they should not 'stick' while threading in. Also, they (generally) seal metal against metal, by design: thread against thread, flare against fitting or fitting against fitting.

Cheers,

CIV

I agree with Marcio (hello there by the way) that is not necessary
but
I personally find a LITTLE grease when rebuilding an old machine and the threads are a little gunkier even after cleaning, helps screwing them in BY HAND before the wrench time comes,
mostly so all the pipes will line up nice before the final tightening down

Sounds like your machine was worked on by a truck mechanic or something! LOL They may also have put on grease as a "coating" to keep oxidation down on the pipes? It would probably work, but oxidation on the outside of the pipe doesn't effect anything.

In general you don't need any grease, but like Stefano pointed out sometimes a little lubrication on the threads can help in assembly when parts aren't so smooth.

If you don't need the grease then leave it off.

Several manufacture use grease even during initial assembly Rancilio is one of them

The grease wasn't on the threads, but on the ends of the tubes, something like a rounded nipple or compression fitting. Could be that the grease was originally on the threads but then migrated to the ends? I'll just reassemble without any grease.

Thank you all for your input.

keep it simple
if they screw in nice and easy with your fingers before the final touch with a tool
forget about the grease

Was also curious about the greasing topic (as I am an amateur motorbike mechanic and a "greasing pervert", as my wife calls me). Associated question about tightening - working on my bikes I'm used to using a torque wrench for tightening things, on the espresso machine I'm going to rebuild soon I don't know how tight the fittings should be. Never worked with copper and flare / compression fittings before, so have no idea. How do you usually tighten, finger tight then some particular amount of degrees with the wrench?