Standards for pipe union fittings?

Hi folks

I am finding model engineering pipework standards confusing, fittings have a nominal size, but can fit more than one pipe size by changing cones and nuts, and everything is imperial.

I have obtained a mix of nuts and cones, and I don't know what I have.

Is there a table somewhere on the internet where sizes are tabulated so I can identify the nuts? I assume I can identify the cones from their internal diameter.

This sort of question has come up before but it didn't help me in the short term, although I hope to be able to find the reference when I can get to the club and look at the old magazines.

thread link

Thanks for the help.

Rog

Don't know about standards, I just design, and make, what looks sensible for the pipe size I am using.

Andrew

Take a look on one of the ME suppliers website at the steam fittings you should soon work out what size fittings cover what size pipe. For ME use pipe/fittings are imperial. Try link

https://www.pollymodelengineering.co.uk/sections/bruce-engineering/docs/Catalogue-current-1.pdf

H

Sorry Harry but I have downloaded the Polly catalogue and it conspicuously does not say what size A/F the nuts are, all the fittings are described solely on the nominal pipe size. The same goes for Macc Models and the ebay retailers I have looked at.

Sorry Roger I thought it may throw some light on 'fittings have a nominal size, but can fit more than one pipe size by changing cones and nuts, and everything is imperial.' for you

H

Doug Hewson has a table of fitting sizes on one of his Britannia drawings according to an article in ME 4666

Roger

I've sent you a PM.

John

The standard dimensions will be found in in places like Bristish Standards, Machinery's Handbook, Kempe's Engineers Year Book etc and other places.

Some research will bring them to light.

"Everything is Imperial"

Since a lot of pipework is Imperial, you should expect the nuts, olives and threads to be in Imperial units. Don't go looking for 6.354 mm pipe; try 1/4"

On the Continent BSP is still used, although it is called Gas, for threaded fitting on taps (faucets ) etc. even if the copper piping is 10, 15 or 22 mm OD.

AND remember that pipe threads will be Whitworth form, and BSP refers to the pipe diameter. but will be larger in OD and have an Imperial pitch.

As an instance, a 1/4 BSP thread is 0.508" OD

Zeus charts will make some of this clearer..

Also be aware of the difference between Pipe sizes and Tube sizes. One is OD, the other is ID.

Howard

Hi Rog,

This is a simple the steam fitting is sized to fit the pipe. The cone fits pipe and the right nut is the one that fits the cone properly. Just like in full size house plumbing you never see a nut size mentioned but a 22mm fitting falls off a 15mm pipe.

All this talk of domestic plumbing fittings, people must be making some big models

Ken Swan's Jessie drawings also contain a table of sizes

Here you go this is even better I knew I had seen something before. This site not only gives step by step on how to make MODEL SIZE fittings but at the bottom of the page is a table of sizes. Download the pdf to see the table full size.

Edited By JasonB on 06/02/2022 19:21:12

Extra Big thanks to JasonB and John Purdy.

Appreciable thanks to all others.

In my 40 years of engineering in the metric era I have found its not unknown for people to decide to not follow BS convention and decide that their fittings can be pretty much any shape they like, this is mainly because parts are made for an international market and they have never heard of BSI. Not unreasonably they usually include a drawing in the catalogue and nowadays the youngsters expect a CAD drawing on the website.

So here I am going back in time to the 1920s and customers are expected to know exactly what size everything is and put up with whatever that is.

Its a surreal situation for me, not a bad one, and its fun learning so thanks again for the help.