Pipe Diameter Question

[Wendell Swedberg]

Here's another ICC practice exam question:

Q: A 2-inch waste pipe passing through a foundation wall shall be encased in a pipe sleeve at least what size in diameter?

A) 2 1/2 inches
B) 3 inches
C) 4 inches
D) 5 inches

Answer: 3 inches.


P2603.5: Any pipe that passes under a footing or through a foundation wall shall be provided with a relieving arch; or there shall be built into the masonry wall a pipe sleeve two pipe sizes greater than the pipe passing through.

My question: Are not pipe diameters in increments of 1/4 inches?

1 1/4, 1 1/2, 2", 2 1/4", 2 1/2", 3, 4,and so on?

Or is it: 1 1/4, 1 1/2, 2, 2 1/2, 3, 4, and so on?
My answer was

[Ken Amelin]

Wendell,

I read the question as it states, use a sleeve 2 pipe sizes greater than the pipe you are passing through it.

The answer depends on what material you are using for the pipe.
Copper, PVC, Cast Iron, or other have different available size increments. You'd need to know those increments in order to select two sizes larger.

If your refering to PVC schedule 40 pipe, the available sizes are: 1/8, 1/4, 3/8, 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 3-1/2, 4, 5, 6, 8, 10, 12, etc.

ACR type copper pipe (ASTM 280) comes in 1/8 inch increments up to 1-3/8, with 1/16 increments from 1/8 to to 5/16

Cast Iron no-hub is sizes are: 1-1/2, 2, 3, 4, 5, 6, 8, 10, 12, 15.

[Wendell Swedberg]

thanks , Ken....no the test question did not list the type of material, just that it's a 2 " waste pipe.