IM using 1.5 inch ABS to replace my old rotted galvanized drain.

I have a straight section that runs in my basement to the tune of about
16 feet

How do you properly pitch this stuff? How many inches per how many
feet?

Right now i have about 2 inches of pitch for then entire run and at the
end....near the main drain pipe for the house......there is a 45 degree
or two that hooks it to the main drain pipe (this section is about 3 -4
feet in length with this desin


))))))))))))))))/
/))))))))))))/

/ (MAIN DRAIN
Galvanized at
45 degree here
and then runs
into the Cast
iron)

Can i get away with this or do i need to have more of a pitch than 2
inches for that long run?

Any feed back is well appreciated. Im wanting to get this thing
together today


I dont know if the drawing makes sense or not but basically i have two
45 degree sections that lead to the main cast iron drain for the house.