Lightly oil the cone of the screw sleeve and the thread of the union nut
With sealing cone screw-on fittings with O-ring (AOL / AOS), the pre-stressing of the O-ring must be bridged and the sealing cone must lie metallically flush against the cone of the HL/HS connector. At this point, the cutting ring may be allowed to rotate, but must not move axially. Tightening torques for stainless steel fittings…