[DeTomaso] [NPC] Black iron/steel pipe (was: Air pressure regulator)

[Mark McWhinney]

I found a local place that has black steel 1/2" pipe, custom cut and
threaded for about $1 per foot.  It's more than PVC but less than copper,
and I can screw it together.

Of course, this begets a whole new set of questions.  :-)

Is black steel the same as black iron?  I poked around on the Internet and
found that the terms are used interchangeably.  If they are different, is
black steel OK for my application?

When joining pieces, should I use Teflon tape, pipe dope, ...?

Is there a problem with joining dissimilar metals -- brass fittings and
valves with black iron/steel pipe?


Related topic -- I found the follow bit of info on a forum.  I don't know if
it is right, but I though it is another reason for going with black iron.


>> 1/2 inch black iron has way more carrying capacity than 1/2-inch copper.
Damn if I know why

1/2" trade size Sch 40 blk iron has an ID of .622" 

1/2" trade size (5/8" OD) type K copper has an ID of .527" 

also: 1/2" OD type K (3/8" ID) is only .402" ID 

Since area goes with the square of the diameter, (and I care only about the
ratios of the areas, not the actual areas, for comparison purposes) dividing
(.527")^2/(.622")^2 = 0.72 so the copper has a little less than 3/4th the
capacity.