Steel pipes

There are two different types of steel pipe: black and galvanized.

Galvanized steel pipe has a protective coating of zinc, which increases its life. Galvanized pipe is usually used in water systems, but never for gas installations (black pipe is used in that case). Highly mineralized water can reduce the life of galvanized pipe.

  
Sizes for Wrought Iron & Steel Pipe
Nominal Size
(inches)		 Outside Diameter
(inches)		 Inside Diameter
(inches)		 No. of Threads
(per inch)
1/4 0.540 0.364 18
3/8 0.675 0.493 18
1/2 0.840 0.622 14
3/4 1.050 0.824 14
1 1.315 1.049 111/2
1 1/4 1.660 1.380 111/2
1 1/2 1.900 1.610 111/2
2 2.375 2.067 111/2
21/2 2.875 2.468 8