Question: what are pipe thread sizes?
Answer: Commonly used sizes are ​1⁄8, ​1⁄4, ​3⁄8, ​1⁄2, ​3⁄4, 1, ​1 1⁄4, ​1 1⁄2, 2, ​2 1⁄2, 3, 4, 5, and 6 inch, as pipe and fittings by most U.S. suppliers.