AS a full time Plumber / Pipe Fitter and SS tubing Guy,
We use tape A Ton, and a Small amount of Pipe Dope middle threads only,
on all our High Pressure Systems. This will keep it sealed. a little goes a long way.
Gasoila Brand Dope for Regular Steel,
PLS-2 for Stainless Steel.
Both can be had at Plumbing supply, or online