Yes to one face flat brass and one with the groove.
I wondered about an O-ring. I haven't ruled it out but think it's unlikely because the groove is only about 0.6mm wide.
This is a 'flushing bypass' manufactured by ITap SPA rated PN16.
The corresponding item from Caleffi does come with an...
Hi all
I am investigating a series of leaks from union type joints on a circulating hot water system in an apartment block. Operating pressure varies with the height of the building but is in the range 5 to 10 bar (70 to 140 psi). Water temperature is about 80 deg C (175 deg F). Nominal...
