Gas Piping

[Neal Lewis]

First time I've seen a reducing bushing used for gas piping. Code says no bushings allowed for cast iron piping. Is threaded black iron the same as cast iron?

And what's the reason it's not allowed?

[Bill Kibbel]

I believe "black iron" is considered malleable and is not cast iron.

I also don't think reducer bushings are an issue for black iron. I've heard an argument about it before and the final convincing word was that many plumbers and code officials are incorrectly calling it as wrong. They're fine if of malleable iron.

And what's the reason it's not allowed?

I don't know - maybe because cast iron is brittle and this fitting is known for failing?

[KGarten]

The International Fuel Gas code (2006) prohibits gas piping from being made out of cast iron (section 403.4.1) although fittings may be made from cast iron. ("Regular" metal gas pipe is steel or wrought iron). There are are number of exceptions to the fittings with bushings not being allowed (section 403.10.4 note 5.2). The code commentary states that "bushings have been known to split from over tightening." Also section 404.3 prohibits bushings of any material to be used in concealed locations, with the commentary stating the "split after assembly" reason.

The National Fuel Gas Code (NFPA 54) has the same restrictions.