The Steamboating Forum

Hello all

(Not sure if this goes in this section or the engines&boilers one, but here it goes)

Now that I have my engine (ST 5A) i would like to buy some valves, lubricator, oilers, nuts and bolts etc to upgrade the engine a little bit and prepare it for real use and then mount it on a wooden board for display and running on air until the time has come to fit it in a boat.

I have been looking through several sites for supplies and found many nice goodies, however I have no idea regarding the Imperial system, I only have experience with the metric system.
I am looking to buy a "thread checker" tool to check what threads I have, but my question is whether steam fittings are all in Inches (fine/coarse) or whether they are different kind of threads.
I don't want to end up buying "thread checker" tools just to find out that they are of no use.

Another important question I wanted to ask was whether there are some thread sizes which are extremely common in the "steam world", or whether every fitting, valve, lubricator etc is available along a large range of threads? Especially for the smaller engines such as the ST 5A,
So i don't have the problem of having to look for a weird solution of several fittings attached to one another just because I bought an odd thread size.
If there is a special (common) size, please let me know.

Another thing (more for the european steam boaters), do you know of any fitting suppliers in Europe?
so far I always ended up on US or Uk websites and the few suppliers I know in Europe are more for large industrial applications.

Thank you in advance

Regards Quinten

I think you will find that your local plumbers merchant will have fittings to suit, as far as I am aware BSP (British Standard Pipe) threads are pretty well universal. The material that the fittings are made of will become a concern when you do finally connect it to a boiler, but for running on air almost anything metal will do.

Mike

Well thats the thing, I directly want to buy steam rated material so I don't have to change anything later, and I have asked at some places over here, but they actually have no clue about steam.
They keep offering stuff for simple water plumbing for the bathroom, or gas pipe fittings and valves and I highly doubt that stuff is suitable for steam application, although it could handle the pressure, I am not sure whether it withstands the heat as well.
Besides, the threads they had were different as well, despite being in inches, but they seemed to have a coarse thread.
which is why I prefer to ask you guys what threads are used and how to identify the right material.

Quentin.

The steam theory is very interesting and as I am finding out there is no perfect solution to almost everything. Almost every decision has a counter arguement or some major implication some place else in the system. It is one big entangled equation and most of it you cannot see.

I was just thinking about your predicament obtaining fittings due to the pressure and the fact that an engine really only needs just a few psi to turn over, relating this to my day job.

Every year I am responsible for making 15 million shotshell cartridges at our company and the pressures can go up to 12,500 psi with each cartridge. Here I am now thinking about a copper boiler tested to just twice working pressure of 160 psi. It just shows how different materials come together to acheive something.

Happy hunting for parts my friend, your journey has just started.....like mine.

Hayden

It is possible that who ever built your engine did not use 'normal' threads. I think you need to find out first what the threads are that you are trying to match up, and then decide if they need converting in some way to something standard.

Direct measurement with a rule is probably best, anything more accurate might be misleading as threaded parts are always slightly under the stated (nominal) size. Decide first if the sizes are metric or imperial. Then determine the Threads per Inch (Imp) or pitch (metric) and work from a thread chart to find them.

UK model engineers use fractional sizes in 60, 40, 32, 26 TPI sizes Whitworth thread form, pipe threads are also Whitwprth form based on the interior diameter of the pipe being threaded with the threads used being 28, 19, 14, 11. Pipe sizes start at 1/16 inch bore in 28 TPI.

Use a piece of closely sized wood to screw into the hole with the thread being measured and use your thread gauges to measure pitch and callipers to measure diameter, then try the hole with a piece of rod cut with the thread you think it matches. The USA have their own screw thread and pipe thread standards

Over the years I've seen quite a lot of butchered threads in small marine engines, Landrovers and horology, but never on a vintage aircraft.

JohnG

Dear Quinten ,
Have a look at this site : http://www.stationroadsteam.co.uk/Stuart/No.5a.htm . This gives the thread sizes that Stuarts said were needed .
Unfortunately it does not follow automatically that the builder of your engine built it exactly according to the plans , but at the very least it should be a good guide .

Regards Edward .

As far as pipe fittings go only BSP or BSPT (taper series) should be used.

As far as engine fixings go, BSW, BSF, UNC, Metric and BA are all used on British engines, all of them are used on one particular engine in some cases!!

You need a Zeus pocket handbook- http://www.amazon.co.uk/Precision-Refer ... ngineering
, it is a collection of all British Standard engineering threads and fixing standards, as well as conversion tables and other very useful info.

Google: Heritage steam supplies and air-link compressors for suitable fittings and pipework.

Greg

Gondolier88

Is there a spec for cobber tubing on the pressure side, between boiler and engine and for any in injector supply lines??

Only for 80 psi working pressure from the boiler.

Hayden

Gondolier.

That should be copper tube!!



Hayden