Unions,threads and pipe sizes.

[rrmrd66]

Good Morning everybody.

As  a "virgin" builder I have, or are about to arrived at the task of planning the layout of piping from the top of the manifold to various points on the engine.

I am confused as to the best way to proceed.

Can the more experienced forum members  recommend a good/reliable supplier of valves (clacks, blowdown, injector etc). I know I could make them all myself as I have the details, but life is to short.

I would prefer to pay the extra for things made in UK.

Also, has anybody a chart/spread sheet, or point me in the direction of, something that ties thread sizes to pipe diameters and associated valves.

Many thanks in advance.

Cheers

Malcolm

[uuu]

Can't help with the valve supplier I'm afraid, but I can pass on some info from Jessie's drawings, where Ken Swan includes a complete list of pipes, cones, nuts etc. Why other designers don't is unhelpful. Here are the sizes used:

Pipe o/d	SWG	fitting thread
1/16"	26	3/16-40
3/32"	24	3/16-40
1/8"	24	7/32-40
5/32"	24	1/4-40
3/16	22	5/16-40
7/32	22	3/8-40
1/4	22	3/8-40

Wilf

[mbrown]

If you are aiming for speed by buying in unions and cones, then Wilf's list of pipe and thread sizes is great, although it isn't always easy to buy 7/32"x40 unions (I believe Polly Models sells them). But fittings will look a lot neater if you go for smaller thread unions which are pretty easy to make. For example, I use 5/32" x 40 for 3/32" pipes, and either 5 BA or 6BA for 1/16" pipes (6 BA is getting rather small for silver soldering the cone onto the pipe). Making unions isn't difficult and you can churn them out pretty fast once you get into the swing of things.

Malcolm

[rrmrd66]

Thanks Wilf and Malcolm

This is really helpful

Anybody else got some good suggestions?

Malcolm

[builder01]

Here's a link to my website that shows how easy it is to make a cone union. At the bottom of the page is a down loadable chart I made of the schedule I came up with for my cone unions.supersimplex.yolasite.com/How-to-Make-A-Cone-Union.php
David

[ettingtonliam]

Wilf's list is useful, but Polly, for example also supply fittings for 1/4" dia pipe in 3/8" x 26TPI, and 3/8"x32 TPI as well as 3/8" x40TPI, as suggested by Ken Swan.
I tend to use the coarser thread, 3/8" x 26TPI because with increasing age and clumsyness, I find it too easy to cross thread the finer, 40TPI threads.

[jma1009]

Hi Malcolm,

I would like to provide some input into your interesting thread, but my elderly RSPCA rescue cat Benny is fast asleep on my lap, and typing is very difficult at the moment!

I've come across some truly awful commercial boiler fittings in recent years, and very badly and sloppily made union nuts and nipples, so don't assume commercial fittings from some well known suppliers will be your panacea!

Cheers,

Julian

[92220]

If you make up a mini tool to flare out the ends of the pipes, you can make unions as small as 8BA with no nipple required. I have on the scale lubricators on my 9f. If making up nipple type unions, as long as they are not handling heat, such as oil feeds, you can fit the nipples using Loctite. There are some Loctites that can operate continuously at around 230C so could even be used for hot liquids and steam but I can't remember which they are.

Bob.

[millman]

UUU, thanks for your details of pipes, cones and nuts, I shall copy them out and pin on the workshop wall.