Just what does the MRO industry mean by Black Pipe?
Black Pipe is a common nomenclature for schedule 40 malleable iron pipe and fittings. You will hear the names black pipe, schedule 40, malleable iron and 150 lb. pipe all used to describe the same product.
What is galvanized (black) pipe?
When you plate malleable iron pipe and fittings it is typically called galvanized pipe due to its dip platting in zinc. Galvanized (black) pipe should not be used with gas systems.
Why do some couplers in the black pipe family look different from others?
You will see more than one style of coupler used in the black pipe family. The first style is a steel coupling — not really an iron fitting and is the least expensive method of joining pipe or nipples, and yes, they can be used in conjunction with malleable fittings.The main difference between steel coupling and a malleable coupling is in the threads. Most steel coupling has straight threads while malleable couplings have tapered threads. Standard steel couplings from 1/8" thru 2" are usually made with straight threads unless you specifically request the taper thread in which case they are much more expensive. If the application is for higher temperatures and pressures, then the taper threaded coupling may be desired. Also, natural gas, in general requires taper threaded couplings. You will also see ground joint unions. These are couplers with a hex in the center to aid installation. There are also reducing couplers that allow you to step down a size.