I've been looking into the re-pluming of an engine cab and this question of pipe quality and fitting fit and what not. One point here, is the pipe extruded or roll-seam. That is a raging issue in the oil drilling industry over strength and durability. Both can be specified equivalent however roll-seam historically fails due to the change in metal chemistry at the seam.

I don't know if anyone here has seen the inside cab pluming or even outside on the "sugar cane train " locos now unfortunately for sale. Besides setting outside in the salty rain, I swear that when they were converted from saddle tankers to tender loco's and the boilers replaced in what 1970, the company used common hardware pipe. Looks like a bunch of non bent straight sections from the hardware department, not real pressure qualified pipe. Perhaps I am wrong but any pipe is only as strong as the exposed thread cut at a fitting change.

Dan

For those that are curious.....
The ASTM B-42 Copper Pipe standard was originally published in 1922.

Thanks to ASTM HQ for the info.

C W

That is true, but not for the reason that you imply!

The Copper Tubing Size (CTS) system is based on an OD that is 1/8" larger than the nominal dimension.

1/2" CTS has an actual OD of exactly 5/8".

One explanation is thus: 1/2" copper tubing is the approximate replacement for 1/2" schedule 40 "water pipe". And after all, there is no dimension on 1/2" schedule 40 pipe that actually measures 0.500 inches. The whole IPS (Iron Pipe Size) system is based on the nominal ID of some absurdly thick-walled pipe, perhaps lead pipe.

There are two ways to specify tubing dimension: according to the CTS schedule, or by stating actual O/D. The HVAC industry simply chose the latter.

Although people may call the 10-ft lengths of 1/2" CTS schedule L in Home Depot "cooper pipe" that is absolutely not accurate. It is copper tubing. Tubing can be soft or hard. Tubing is best defined as a thin-wall product. If you can thread it or groove it, it is pipe.

Then there is "hose" which is generally sized by ID, but I digress.

Back to O/P question: There were a lot of oddball sizes. I believe 2-1/4" copper pipe is what David and others have implied, a thick-wall copper pipe (not tubing) that was connected by threading. Since the wall thickness of copper pipe must be a bit heavier than steel pipe for the same pressure rating, 2" steel pipe and 2-1/4" copper pipe have about the same ID. The minimum ID would be governed by the steam flow rate requires.

No, it was based on the material in the name, iron, in this case wrought iron. Having less tensile strength than steel. the ID's of the original Wrought Iron Pipe were very close to their nominal sizes. It's conversion to steel that screwed all the dimensions up.

From the Machinery Handbook, 11th edition, 1943 we see the table of copper pipe, (not tube) sized to match the dimensions of iron pipe. NYCRRson says that he disagrees with my statement that CPS (copper pipe sizes) is the same dimension as iron pipe, but we see here it is indeed the same. In fact, I have purchased copper in CPS which is identical to iron pipe sizes even down to the available lengths of 21 feet. I agree that it is a tangled mess unless you actually work in the pipe world and then it is only a little messed up. C.W. Craven is correct in that the B-42 was published in 1922 however I don’t think it applies in my original question. Although I asked about the Hancock publication, my Sellers catalog 1902 makes the same distinction in iron vs copper and different sizes.

We also see the pipe being measured and we find that the od is 1.660 which corresponds to the od of 1-1/4" iron pipe.

And we see the id being measured and with a little math it turns out the the wall is .140 which is the wall of 1-1/4" iron pipe, schedule 40.

But that info doesn't tell us whether the max working pressures are equivalent. I would suspect that just like iron pipe, copper pipe likely came in several grades (schedules now). Your 1943 source also doesn't go back far enough to fully coincide with the original question; the injector literature was specifying quarter inch sizes that are no longer shown in the table you present. Like everything else, materials fall out of favor; the market disappears, then even the specifications disappear.

Maybe this will help. From my 1957 edition of Machinery's Handbook, 15th Edition.



I'm not sure if this is any further help.

Interesting. The 1-1/4 pipe with 0.140 wall thickness would have a bursting pressure of 650# according to this formula. If we go with a 1/6 factor of safety as suggested, this pipe schedule would not be satisfactory for 200# boiler pressure.

I tend to think this verifies the premise that with copper pipe, a thicker schedule would have been necessary to safely handle the boiler pressure, and thus smaller ID. In order to avoid wire-drawing the steam you would have gone up one pipe size when using copper. Now, you steam guys have to explain to me what an "inspirator" is!



Wrot Iron must have been an awful material to work with for pipe fitting.

I wonder when the NPT thread came into existence?

Interesting. The 1-1/4 pipe with 0.140 wall thickness would have a bursting pressure of 650# according to this formula. If we go with a 1/6 factor of safety as suggested, this pipe schedule would not be satisfactory for 200# boiler pressure."

The 1957 version of Machinery's Handbook shows 1 1/4" pipe with .140" wall thickness as "Standard Weight" (Standard wall) pipe. "Extra Strong" 1 1/4" pipe has a .191" wall and Double extra Strong 1 1/4" pipe has a wall thickness of .382".

I'm including a scan of the page. Notice the right hand page with the more familiar pipe schedules listed

The print in the previous photo didn't come out well. Also, when the newer standards for pipe were adopted the "Double Extra Strong" pipe has no corresponding Schedule #.