Though normal pipe sizes are listed in standard sizes (2", 2.50", 3" etc) the actual inner & outer diameter of the pipe is actually different. This is how pipe (rather than tube) is measured. Below are the actual sizes.
Detailed Specifications:
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Actual O.D. - 6.62"
Actual I.D. - 6.35"
Height 9.00" (measured from I.D. center to center)
Wall Thickness .134"
Elbow degree: 90
Material: 304 Stainless Steel