A well made flare does not require any lubricant to seal properly. The fact that he torqued the flare nut is an indication of quality work.

Hard NO on RTV silicone.

 

Oil or Nylog should be applied to the shoulder of the flare to prevent distortion of the tubing when the nut is tightened, not to the mating surface.
Why would you put RTV on the outside of the flare nut?? Surely you don’t think that would stop a leak of 600 psi that the flare couldn’t hold?

 

Thank you for your valuable response!

Will not be requesting to put RTV. That's something I read online to prevent the nut from loosening with respect to contraction/expansion. But it clearly is not the right approach.

Will also not request to open the flare and oil/tighten again.

Is re-torquing typically needed after a few days of refrigerant release, or say a quarter?

 

Nylog
All the time

 

Flares depend on the tools used to do the flare.
Torque is the important step, and a quality flare job.
I do use nylog on the shoulder of the fittings.
It certainly is not a necessity.

 

Ever see SWAGELOK fittings? A bearing surface between the nut,and collet. 10,000 psi hydraulic fittings.
So nyloc on the shoulder is a good tool

 

Nylog is not acceptable according to some manufacturers, our company is a dealer for a company that will not warranty if nylog is used. They instead recommend vacuum pump oil on the back of the flare to prevent galling. It is not required but best practice. I am not saying I am against nylog but some manufacturers say no.

 

and how in the hell are they going to know really!

 

Double flare then half a drop of oil on the back side. Except, I always seem to forget the oil.

 

As you can see, everyone has different opinions.
The correct procedure is spelled out in the install manual, whatever procedures the manufacturer specifies are what should be done.

Most manufacturers require a special flaring tool designed for mini-split flares, not grandpa's flaring bar. This is a point of contention but the fact is that the flares are different. The flare cones should be lightly oiled to prevent shearing when tightening. Finally, the nuts should be tightened with a torque wrench to the spec listed in the manual.

99.98% of leaks on mini-splits are from improperly made flare connections.

If your installer didn't oil the flares but they hold a pressure test then they're fine and you don't need to demand they re-do them. If they damaged the flare when tightening it would definitely leak.