The female threaded union (FU) is used to connect two units with MNPT fittings.  The FU is best suited for low-pressure applications.  This product is available in both Carbon Steel and Stainless Steel and conforms to ASME B16.39 and ANSI B1.20.1

Female Union:  Stainless Steel / Carbon Steel | Precision Hose & Expansion Joints

Female Union: Stainless Steel / Carbon Steel

HOSE
SIZE
1/4 3/8    1/2 3/4 1   1-1/4 1-1/2 2 2-1/2 3 4
A 1.84 2.11 2.35 2.77 2.94 3.01 3.22 3.50 4.25 4.54 4.90
B 1.46 1.61 1.72 2.02 2.19 2.26 2.47 2.75 3.25 3.54 3.90