Sure it's not a 4" pipe?
http://www.engineeringtoolbox.com/cast-iron-soil-pipe-dimensions-d_1751.html

 

I'll check the measurements. Thanks.

 

If this is a residential house you have 4" cast not 5".

 

Ive never even seen 5" pipe .
3-4-6-8-10.........

 

Agree with TheEplumber..
We not have much uses of drain iron stack. but if size is your're sayin..5"
the best option in a 4" riser clamp ..
A normal riser clamp have 2" screw.. so it is good with that

 

Yeah I remeasured and I don't know how I convinced myself it was 5 inches. Going back to get a 4 inch clamp.

 

I need a riser clamp to hold a section of my cast iron stack while I cut it. The outer dimension of the stack is 5" so I asked for a 5" riser clamp. But it seems to big. I expected it to wrap pretty close around the pipe but it doesn't. Did I ask for the wrong size?

Ayuh,.... There's yer Problem,.....

Pipe is sized by it's Inside Id,...

 

The 4" clamps fit great