Duplex strainer will require 4 straight through valves, one
on each of tee, or two 3-way valves in place of tees.

Style:
FBIO - Flanged Both Inlet and Outlet
BW - Butt Weld
FIBO - Flanged Inlet, Butt Weld Outlet
FOBI - Flanged Outlet, Butt Weld Inlet