Fitting 1/2" hole dia 14mm

A welding end cap nut is used to put pressure on the welding cap so it seals against the conical surface of it. Once there is not enough pressure from the back from the welding cap nut, the seal won’t work.

This type of welding end cap is slightly different then the standard types of caps.

You will see this type of fitting for instance on the water level of the Faema E61 espresso machine, on the flange side.

The thread used on this fitting is a male ½”BSP-G. This one is smaller then the one used for the brewing groups. This fitting  can be used in combination with a 10mm copper tube and it’s matching solder fitting.