As is often the case on this forum, Guy Wilbur has posted the correct information. I am currently revising my Freight Car Underbody Detail clinic and attendant handout and the information on placement of angle cock is fresh in my mind. As I said, Guy is correct.
I have an angle cock complete with 22 inch hose (Guy, did mine shrink a half an inch?), 10" pipe nipple and air brake hose coupling which is often referred to as a "glad hand." (Truckers use the term glad hand as well for the dinky little things they have between their tractors and trailers.)
My nipple/angle cock/hose/coupling assembly came off (with permission) a 1937 AAR 10-0 IH box car. The angle cock still has most of the original paint on it, no accumulation of crude but rust were the paint is gone. Ditto for the coupling except that there is more rust and a lot less paint.
The hose is a very dark gray and anyone looking at it would call it black. That which came off on my hand when I picked it up just now would be termed "black" by any mother in the land.
There is more than one permissible way to secure the hose to the fittings on either end. Automobile radiator hose clamp is one way. Mine are held on with ferrules and these are still a silvery, metallic color with a yellow hue suggestive of cadmium plating???. They stand out as "silver" on an otherwise fairly dark assembly.