Fittings
The most common thread type is the BSP-G thread. This is the British Standard Pipe Gas thread type. You do also find this thread type in gas and water installations in your house.
The disadvantage of brass is that it can oxidize quite fast, when it is plated with a nickel coating this doesn’t happen anymore.
The T.E.A.+ coating is a alternative to nickel and nickel and chrome plating. Which is quite commonly used on espresso machines
In most cases the fittings on espresso machines are made from brass with a low lead content, which is allowed for espresso machines.