7000 Series Ermeto Steel Flareless Fitting, 1.00 Inch Tube OD Small Hex Union

Extra heavy wall tubing is actually one of the main use cases for this fitting. Standard flareable tubing can usually be handled other ways, but when wall thickness makes flaring impractical or impossible, that's exactly where the 7000 Series Ermeto steps in. It's compatible with aluminum, hard or half hard copper, steel, stainless steel, and extra heavy wall tubing that can't be flared. So yes, heavy wall stainless is well within scope here.