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Difference between Malleable pipe fittings & Black Pipe Fittings

Difference between Malleable pipe fittings & Black Pipe Fittings

Difference between Malleable pipe fittings & Black Pipe Fittings

(OP)
Hello folks,
Can someone tell me what difference is between Malleable pipe fittings and Black pipe fittings?
I appreciate your time.
Thank you in advance
Sammy

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

Are you asking about black steel or black iron fittings? Although the post from John should explain it for you.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

I'm pretty sure I've seen "black iron" used simply to mean "steel that isn't galvanized", unlike what that first link says. I think the "Black Iron" pipe on the Lowe's website is the same as the "Black Steel" on the Home Depot site which is A53-A steel pipe per the description.

On the original question- malleable iron is a type of cast iron, different metallurgy and higher carbon content than steel.

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

They are two different material, i.e. different in chemical composition as well as and mechanical strength. In terms of the service limitations, the black pipe fitting has higher mechanical strength than the Malleable iron fitting.

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

Gray cast iron threaded fittings in small sizes (1/2-2") are no longer available, or if they are, they're rare enough that I've never seen one in the ~ 25 yrs I've been dealing with fittings on a daily basis.

If you find a 150# threaded fitting which sticks to a magnet, it is almost certain to be malleable iron, whether it is galvanized or black (not galvanized). These fittings are also made in cast stainless steels such as CF8 (304) and CF8M (316).

3000# threaded fittings are generally A105 carbon steel forgings, not castings.

300# malleable iron fittings do exist, and just to make confusion more likely, they have dimensions very similar to 3000# forged steel fittings.

That link that John R Baker posted is very confusing. I've never heard of "black iron pipe" before, and suspect that it is a misuse of the "black iron" description of non-galvanized black malleable iron fittings, misapplied to the pipe which is STEEL I am unaware of an ASTM designation for anything called "black iron pipe". I do know what centrifugally cast iron pipe is, and it is still used in drainage applications, but it is NOT joined by threading.

Steel pipe here for pressure applications is typically A53 welded (or sometimes seamless) or A106 seamless. Those are steel, not "iron". There are steel pipe and round hollow structural steel (HSS) grades available for use in non-piping (structural) applications which are identical in dimensions to pressure pipe, but which use much less reliable "furnace welding" or other means to form the long seam, so you do have to be careful making assumptions about spec/grade based on dimensions alone.

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

moltenmetal....black iron pipe is a contractor's misnomer, much like using "footer" instead of "footing". You are correct...it is black steel pipe.

RE: Difference between Malleable pipe fittings & Black Pipe Fittings

Ron, I figured as much, but felt it necessary to correct the rubbish posted in the links provided by JohnRBaker.

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