The traditional formula for maximum shear stress due to transverse shear in a pipe is 2V/A, where V is the shear and A is the cross sectional area. Given this you could think of the shear area as A/2. However, if you are designing steel per AISC it's a moot point because it uses the gross area and divides it by 2. See equation G6-1 in the AISC 14th ed.

I ran a simple problem in STAAD and it ignored the shear area it had for the pipe in it's standard list of American HSS Round and used the gross area per the AISC formula I mentioned. Which is the correct way to do it.

BTW, STAAD uses 0.6 x Area for shear area of pipe for the pipe I pulled from the list but 0.5 when I defined the pipe using the same OD and ID. I don't even know what to say.

Do you really have a case where shear in a pipe is controlling? The bottom line is you need to understand this mode of failure and do your own hand check. Don't just trust the black box.