ISO 6164:2018

This document gives general and dimensional specifications for flanged heads, flange clamps, ports and mounting surfaces applicable to four-screw, one-piece square flange clamp type tube connectors and hose fittings for use at a pressure of 42 MPa [420 bar[1]]. It also specifies the dimensions of the seals to be used, as well as the grooves that house the seals.
These connections are intended for application in hydraulic systems on industrial and commercial products where it is desired to avoid the use of threaded connectors.
[1] 1 bar = 0,1 MPa = 105 Pa; 1 Pa = 1 N/m2.