Hello everyone!

I restore vintage espresso machines and right now I have one machine
with really strange threads, which are used on pipe connections. The
machine was manufactured in Italy in the 50s. Here are some examples:

TPI 20 diameter 14.9mm = 0.5866"
TPI 20 diameter 19.25mm = 0.7578"
TPI 16 diameter 20.25mm = 0.7972"
TPI 16 diameter 22.8mm = 0.8976"
TPI 16 diameter 27.7mm = 1.0905"

Does anyone know what kind of threads it might be?

Many thanks,
Julius