How many times can you assemble/disassemble fittings?

pcloadletter

All of this talk about period maintenance on boilers got me to thinking, how many times can you assemble/disassemble pipe and fittings before they should be replaced? I assume the simple answer is "when they don't fit right anymore".



When I use flare fittings for gas my usual rule of thumb is use it once and it's done, but I'm sure brass and iron fittings will survive through a few cycles.



Thoughts?

Steve Whitbeck

unions

Most manufacturers of mod/con boilers have unions on the gas valves.

I allways install the union on the gas line right next to the boiler in case the piping has to be taken apart.

I also use copper anti sieze on all nuts, bolts and screws that I remove.

I would think that if fittings are not over tightened and properly lubricated would last longer than the equipment. Flare fittings included.

Jamie Hall

There are some exceptions...

but in general my experience has been that threaded fittings can go on and on.  I'd be very cautious about reusing a flare fitting -- not so much the fitting as the tubing -- and the big exceptions are compression fittings and lock nuts which depend on either elastic inserts or deformed threads for their locking.  Those are, in my humble opinion, one shot deals.

Steve Whitbeck

fittings

Compression fittings don't belong in any HVAC system unless it is feeding fresh water to a humidifier or feeding a FillTrol valve. And I agree compression connections are a one time and done connection.