A side: ISO-KF40 / KF40 / NW40 /QF40 flange
B side: 1-1/2 " Male NPT tapered thread, follow USA standard
Pipe sizes do not refer to any physical dimensions.
1-1/2" NPT pipe thread when you measure it. It is actually 1.9" instead of 1.5"
TPI: 11-1/2 TPI | Thread angle 60 degree