Boiler Feedwater Line in IBR

hi friends,

the boiler feed water line goes to exchanger (MP steam generator) with the pressure more than 3.5 Kg/sq.cm will come under IBR or not?

i am working on refinery project in which the boiler feed water header is of 6" and design press and temp is 40 Kg/sq.cm and 150 deg c. one branch from this header is connected to MP steam generator (3" size- as stated above). befor steam generator there is check valve. and that header at discharge of pump is having check valve.

so which part will come under IBR and which part is Non-IBR.