notes on iron pipe dimensions

cast iron pipe bushing

While trying to build a monitoring system from my heating oil tank, I discovered the madness of figuring out pipe dimensions. I had in my hands a fitting of some sort with the following written on it: 2x1 1/2. I measured about every possible angles on this fitting without anything coming close to 2 or 1.5 inches. Here is a table to help me/you find the right piece to the puzzle. Sources:

glossary

  • NPT - National pipe thread. U.S. standard for threads on pipes and fittings.
  • O.D. - Outter Diameter (including threads)
  • I.D. - Inner Diameter (excluding threads)
  • TPI - Threads per inch

dimension reference

Nominal
NPT Size
O.D. I.D. Thickness TPI Pitch
1/16" 0.3125" (7.94 mm) 27 0.03704" (0.94082 mm)
1/8" 0.405" 27 0.03704" (0.94082 mm)
1/4" 0.540" 0.364" 0.088" 18 0.05556" (1.41122 mm)
3/8" 0.675" 0.493" 0.091" 18 0.05556" (1.41122 mm)
1/2" 0.840" 0.622" 0.109" 14 0.07143" (1.81432 mm)
3/4" 1.050" 0.824" 0.113" 14 0.07143" (1.81432 mm)
1" 1.315" 1.049" 0.133" 11.5 0.08696" (2.20878 mm)
1-1/4" 1.660" 1.380" 0.140" 11.5 0.08696" (2.20878 mm)
1-1/2" 1.900" 1.610" 0.145" 11.5 0.08696" (2.20878 mm)
2" 2.375" 2.067" 0.154" 11.5 0.08696" (2.20878 mm)
2-1/2" 2.875" 2.468" 0.204" 8 0.12500" (3.175 mm)
3" 3.500" (88.90 mm) 8 0.12500" (3.175 mm)

where to buy

  • Ward Fittings - Bulk orders, they don't sell online but their catalog with prices is available as a PDF (as of 2010-10).
  • Amazon - Lot of stuff available over there. No easy way to search but with patience you can buy small amounts.
Bertrand Janin <b@janin.com> · Powered by the spirit of the UNIX gods.
This page was last updated: 2010-10-08 20:05:23