Got boiler: questions about fittings and dents

[jamespetts]

I have recently bought a "new old stock" Stuart 504 boiler over eBay, which, although it has evidently never been used (it is still in its original kit form), is also evidently very old: from the "Stuart Turner" in Henley days.

However, I am somewhat concerned that, despite never being used, the drum seems to have two small dents in it, not immediately visible, but can be seen and felt on close examination. Both are approximately 1-2cm square in area.

Is this a serious concern, provided that I use a standard feed pump, check valve and new Stuart pressure gauge to run an hydraulic test to 120psi according to the gauge?

Also, the instructions for fitting the gauge glass are somewhat cryptic:

The fittings are made steam tight by wrapping round the screwed ends a few turns of cotton (flourishing thread) soaked in a mixture of white lead and linseed oil. The cotton is drawn through the fingers to remove the surplus. Using this packing will give sufficient latitude to enable a fitting to be screwed in until it is in just the position required. After the ends of the water gauge have been fitted, the glass must be packed. A 1/8-in. of rubber tubing is excellent for this. Alternatively, cotton may be used....

I must confess, after reading that, I am still at a loss as to how to fit the gauge glass: what is white lead, and where do I get that and linseed oil? What kind of cotton is "flourishing thread"? Is there an easier way of doing it than home-treating cotton? Where would I find "1/8-in. of rubber tubing"? Are the two rubber washers included in the fittings packet what they are referring to?

Sorry to ask so many questions, but I am rather new to all this. I am beginning to think, especially following the asbestos incident, that I'd have been better off paying the extra for a brand new Stuart SH-4.

Any advice would be very much appreciated.

[ron]

Hi James
Don't worry about the dents, copper is a very forgiving metal, as long as they are minor depressions without any creases I wouldn't even bother pressure testing a NOS ST boiler, they are well over-engineered!
As to the gauge glass use either very fine O rings available from the usual suspects or make a couple of rings from something like soft neoprene tubing, put the glass tube in postion and NIP up the unions onto the seal with just enough pressure to seal the glass, do not overtighten, finger tight will probably do. Don't bother with all that linseed oil stuff, it's instructions from a bygone era. If this isn't clear I'll post a pic of a part dismantled gauge glass tomorrow.
You will also need to get something to replace the original asbestos panels, these side panels get VERY hot and you want the heat going into the boiler not out the side!
Ron

[jamespetts]

Ron,

thank you very much for your reply - my father and I are in the process of trying to work out how to do the gauge glass, with very little success! A picture of a gauge glass on a Stuart 500 series boiler partly assembled would be very useful indeed.

The instructions are somewhat unhelpful, and do indeed appear to be from a bygone era. It seems that it is necessary to cut the glass tube to length, as it is far longer than the space between the metal fittings. How does one go about cutting glass, exactly, and how best to measure exactly enough?

Thank you again for your help,

James

Edit: What is the best thing to replace the asbestos panels with? I was thinking of attaching water tanks to the side somehow to insulate the firebox and pre-heat the feedwater supply at the same time, but cannot think of a good way of affixing them: do you have any suggestions?

[AndrewP]

James
I've used ordinary plumbers PTFE tape on such threads and if you roll some up lengthwise it can also be used to pack the glass, rubber or plastic tube is easier though, maybe an O ring if the fitting will accept it.
Cheers, Andy

[jamespetts]

Andy,

PTFE tape - that sounds like a good idea! Thank you.

Incidentally, what sort of paint should I use for the cast iron parts?

James.

[baggo]

I'll second the PTFE tape for sealing screwed threads on fittings - it's cheap and very effective. I've tried all sorts of gasket goos with varying degrees of success but PTFE works every time.

For gauge glass seals I cut thin rings from suitably sized silicon tubing. Slide a length onto a drill shank or similar in the lathe and part off rings with a sharp knife. Make a dozen while you are at it! As Andy says, rolled up PTFE tape will also work as well.

To cut the glass tube just file a nick in it with a file and snap it between the fingers - like snapping a pencil in half! As regards length - make it long enough to sit in the bottom fitting and enter the top fitting enough to avoid it being gripped when the top nut is re-fitted. As Ron says, only tighten the nuts by hand to avoid putting excessive load on the glass which may cause it to break under steam pressure - spectacular but not to be recommended!

Some of the ME suppliers such as GLR sell a ceramic material for boiler insulation in various thicknesses - perhaps that would be suitable to replace the asbestos?

John

[jamespetts]

John,

thank you for your reply. I don't have access to any machine tools, so rolled up PTFE tape it is! (Although, wasn't that what the rubber rings included with the boiler fittings pack were for?) What sort of file should I use to pre-cut the glass?

As to boiler insulation, that is helpful, I shall have to look into that. Any thoughts on whether it would be possible to attach feed-water tanks to the outside metal walls simultaneously to insulate the firebox and pre-heat the feedwater?

James

[steam4ian]

G'day James.
A small triangular file may work on the glass, make a ring all round and a nick on the top side. You could get a glazier or lead lighter to do the job, they will have a diamond scribe.
BTW I went to a glazier to get some thin slips of 2mm glass to go in a level gauge (not tube type). He cut them at no cost so I put $2 in the charity box he had.
The asbestos replacement; go to a building site and get a scrap of glass fibre building insulation, tease it out until you can compress it between the housing and the boiler. regarding the tanks, they will soak up the heat and you will finish up with boiling water in the tanks and no steam. You may need to put false sides inside the fire box to stop the flame impinging on the walls of the box, the liner should be stainless steel but MS will do. Space it from the outer wall, insulate as above.
Unfortunately you can't get "white lead" any more, even more unfortunate, you can't get red lead, it was the best prime coat for difficult surfaces. Modern water based paints are just not as good.

Regards
Ian

[ron]

Hi James
Here is a picture of a partially dismantled gauge glass, it isn't an ST one but the principal is the same. You can see the neoprene or silicon rubber ring that forms the seal when the gland nut is nipped up, although as others have posted a rolled up bit of PTFE tape would work as well.
If you want to paint the steel and CI parts the best I have found is Sperex exhaust manifold paint, I tried barby paint but that burnt off even with the asbestos insulation!

Not sure whether your idea of using water tanks as insulation would work or whether it would absorb too much heat from the burner that should be going into the boiler? but you really will have to get some form of insulation on the inside of the combustion chamber as it gets seriously hot even with the asbestos panels fitted.
Ron
PS if you look up item 330176468419 in Ebay there are some good pictures of a complete 504.

[spurley]

Hi there

If your gauge glass fittings are not yet installed in the boiler, please make sure they are correctly aligned before fitting the glass tube.

A good way of doing this is to screw one fitting fully 'home' following up with the second and rough align by eye, then remove the top fitting nut (allowing the glass to enter later) and drop a drill bit the same outside diameter as the glass into the two fittings. Then any fine adjustment can be made before installing the glass. If the fittings aren't correctly aligned or the nuts overtightened you risk the breakage that John (Baggo) described above.

Cheers

Brian

[Tel]

teflon tape, triangular file and alignment have all been mentioned - covers all I have to say about 'em.

[jamespetts]

Thank you all very much - that is very helpful, the picture especially. What I cannot understand, however, is that the nuts on my gauge fittings will not go all the way over the gauge glass as shown in the picture: the narrower end of the nut is just too narrow, so it is not possible to get the nut to fit over the glass. Is something horribly wrong with my boiler, or does it just need filing down?

Also, the picture on the eBay link shows two union cocks fitted to the water gauge: I assume that they are used as "blowdown" valves, although, I must confess, I am not sure exactly what blowdown valves are for. What does that arrangement achieve, and, if I wanted to do it that way, how would I go about setting it up?

Thank you again for all your help, everyone;

James

[baggo]

Hi James,

It sounds as though the gauge glass that came with the boiler is the wrong size i.e. too big a diameter. The nuts should be a loose fit over the glass.

The shut off cocks on the water gauge (not always fitted as on Ron's gauge) are presumably meant to isolate the glass in event of a breakage although I would not fancy trying to turn them off if the glass did break under steam!

The blow down valve on the bottom fitting is to clean out any rubbish that may collect in the gauge glass - opening the valve will allow steam and water to flow through the glass and clean it. In larger boilers this is used to test the water gauge response and to check that the passages in the fittings are of adequate size. When the blow down valve is operated the water level will drop in the gauge glass and when closed again the water level should quickly return to normal. If the level takes a long time to return to normal the passages in the top and bottom fittings are too small.

John

[jgb7573]

HI James,

As Baggo says, it sounds like the glass is the wrong size for the nuts. If the glass is just a little bit too large to go through the smaller end of the nut, then you should be able to enlargen that hole with a bigger drill. That may be easier to do than to find another length of glass tube.

A blow down valve on a gauge glass is very useful in our models. The shut off cocks are less so in my view. They were very common in full size so a model will often have them to "look right" rather than to be used for real.

[Shawki Shlemon]

Every thing has been mentioned You should be OK now but just remember that glass expands with heat and it will be a good idea to allow one or two mm for that . I have seen one breaking when hot and all it was there was no room for expansion . Make sure the glass is reasonably round , this may sound silly but I bought some with shell back and was not round , it leaks and if it is tightened it will break .

[circlip]

With all due respect to steam4ian you would be better locating some Ceramic paper
insulation which replaces asbestous. I can't help but think that in future years that
due to its fibrous composition, 'fly' and irritant nature that glass fibre insulation will
become the new 'Asbestous'.

[lancelot]

Hello All,
while we are on the subject of Stuart Turner Babcock boilers, was there any ''Firing Up'' instructions issued with them, I myself have just invested in one, the issue of ''Asbestos'' if there... should not pose any problem. If anyone with information on the running and care of these boilers would like to post it here or email me a copy, it would be much appreciated.
All the best for now,
John.

[ron]

Hi John
The 504 I have has now been converted to gas firing as I found the spirit burner very effective but very uncontrollable. Basically all you have to do is fill the burner with meths, make sure it soaks the wicks in the firing tubes [takes several minutes] and light it, a fill usually lasts for about 20/30 minutes from memory, only problem I had was I kept getting a flame from the vent hole on the filler plug. If you start with the boiler water level near the top of the glass the water and meths last about the same time if you get what I mean.
If the asbestos is in position and reasonable condition I would leave well alone, I don't think the boiler will be very efficient without it, personally I think the risk is infinitesimal, but everyone to their own.
I bought a large oblong ceramic gas burner [about 5"X2"] it's probably not ultimately as hot as the spirit burner but it doesn't fade with time and it's easier to control the steam output rather than using the safety valve.
Ron

[lancelot]

Hello Ron,
thank you for the reply, I had been tkinking of the Gas option but will play it by ear for a time to see how it plays out, the ''Asbestos'' ...Not bothered...I am going to use it to drive the 10V...Score and Coombes [when finished] I doubt it would drive the Corliss, maybe...
All the best for now,
John.

[ron]

Hi John
What size is the Corliss? I can just drive a ST No 9 with the 504 which has the top of the boiler barrel clad with hardwood strips to try and increase the efficiency.
The No 9 is 1.5" bore and is probably still a bit tight as it hasn't really had much running as I got carried away building the Simplex.
Ron