VIEGA Rotguss Elbow 90°, 1/2″ Male x Female Thread, Gunmetal (Brass Alloy), Art. 264024

The difference is where the thread sits: a male thread is on the outer side of a part, a female thread inside its bore. This 1/2" elbow has both: the R1/2 male end screws into a valve, coupling or tee, and the Rp1/2 female end takes a male-threaded pipe or nipple. That is why it fits between a female port and a male-threaded pipe.

Both joints seal in the thread itself, because R and Rp threads to DIN EN 10226-1 need no flat gasket. For this Viega permits hemp with sealing paste, PTFE thread tape or thread-sealing cord, using only non-hardening sealants with the DVGW mark. You can wind hemp straight onto the knurled male end, but roughen a smooth mating thread first so the sealant is not pushed out as you screw it in.

Yes. Viega lists heating water and gases among the media for its Rotguss threaded fittings, and the range is approved for gas installations to DVGW-TRGI 2018. A gas line may only be installed by a firm qualified for natural-gas or LPG work, and it has to pass a load and leak test before it goes into service.