Union Pacific Big Boy in 3/4 Inch Scale

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RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sun Dec 31, 2017 11:37 am

Hi,

Finally, we were ready to try for my goal of 200 psi. which was a nice round number just a little over twice the working pressure (90 psi.) that I expect to run the Big Boy at. With 200 psi. as the proof pressure I could run at 100psi. if I wanted to.
Big Boy pressure test-(start of pressure increase)a.jpg
Big Boy pressure test-(next step of pressure increase)a.jpg
Big Boy pressure test-(3rd step of pressure increase)a.jpg
Big Boy pressure test (peak)a.jpg
Don took the pictures while I did the pumping. Yes, it leaks a bit, but it does take the pressure and nothing broke or carried away. The pumping peaks were 200 psi or even slightly more although Don wasn't able to capture them on film. That's one reason why I wanted an independent witness.

In these pictures you can see the plugs for the safety valves. All of this stuff I'll keep for club pressure testing in the future and that's also why everything is made from bronze.

While its only a few posts, this covers about two months work for the various stages. I'm glad it worked!

Richard Trounce.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sun Dec 31, 2017 11:47 am

Hi,

Here are a few pictures of the safety valves including the "O" ring sealing adapter I added. I still have to set them to 90 or 95 psi.
Safety Valve -1a.jpg
Safety Valve -2a.jpg
Safety Valve -3a.jpg
Safety Valve -4ajpg.jpg
Safety Valve -5ajpg.jpg
In the pictures, you can see the "O" ring sealing carrier I added to each valve and in the final picture, you can look down inside the valve and see the pressure spring.

I hope all this helps a bit.

Richard Trounce.

James Powell
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by James Powell » Sun Dec 31, 2017 11:59 am

http://home.ca.inter.net/~mguy/a_cure_f ... _tubes.htm

Done in 2005- I'm quite sure Micheal would answer questions if you email him. I think he's been more involved with the full sized stuff since, as the garrett hasn't progressed much !

James

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Sun Dec 31, 2017 12:03 pm

Hi,

If I remember correctly, sodium silicate is also called "waterglass" and used to be used for preserving eggs.

Richard Trounce.

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Bill Shields
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Bill Shields » Sun Dec 31, 2017 1:15 pm

caution regarding use of Ginger...It is not something that you do once and forget.

Once you start using it to seal leaks, you need to CONTINUE to do so, otherwise...the leaks return because the ginger will dissolve....so you have a loco that smells like an animated ginger snap cookie going down the track.

you also need to be careful about washing the boiler with vinegar or CLR or sulfuric acid, as it will take the ginger right out as quick as you can read this.

the high temp Loctite my friend used was good to 400 F - which is about 100 F below where our boilers usually run.

There is some new stuff good to 500F - give or take...of course this is thread sealant and is made to be used on something screwed together..which is why my friend started with threaded stays, screwed in from the outside.

Another way to go about what you are doing is to find the leaks, then pull a vacuum and suck the stuff in...which is a way to clean the leaky area before you resolder...dunk the boiler in acid, pull a vacuum on it and clean the leaky area so that you can resolder.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Mon Jan 01, 2018 10:21 am

Hi,
I'd like to thank Fender (Dan Watson) for his suggestion on how to use sodium silicate to seal leaks. If necessary, I'll use that in the future. I'd also like to thank Bill Shields for his comments on ginger. After filling the boiler with water and emptying it, I don't know if there is very much if any ginger left inside, but the sodium silicate sounds like the better choice to use in the future.

I'd also like to thank the rest of you for your interest and comments. It is appreciated. For me, this is a long term, slow project with many facets and like the couplers (another thread), I work for quite a while without posting my progress. Remember, just because you don't see anything, it doesn't mean that nothing is happening.

Thanks again.

Richard Trounce.

Steve Bratina
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Steve Bratina » Mon Jan 01, 2018 10:43 am

The water glass is good for sealing (pinhole) leaks but not for sealing poor solder joints. If the boiler is structurally sound but weeps through these pinholes, SS will do the trick. If the boiler seals then leaks again as the pressure increases, your physical structure of the boiler is being compromised. One of your pictures looks like the stay and solder have not bonded and could pull away under boiler pressure.
You may need to look at a replacement boiler if the boiler will not seal 100%. When I say the boiler, I mean the actual copper structure and not the various valves that may still be attached.
I have used SS successfully many times but the actual boiler I was working on was still structurally safe.

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Fender
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Fender » Mon Jan 01, 2018 11:06 am

Richard,
Yet another way of sealing these leaks is to mechanically “caulk” the leak. A fellow live steamer explained to me how he repaired a leaking copper boiler that another guy had given up on being able to fix. He marked the leaks, then used a hammer and cold chisel to raise a small burr next to each leak. The action of forming the burr deformed the metal enough to close up the gap. He kept at it, fixing ever smaller leaks, until the boiler held pressure.
Last edited by Fender on Mon Jan 01, 2018 11:24 am, edited 1 time in total.
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Steve Bratina
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Steve Bratina » Mon Jan 01, 2018 11:12 am

I used to caulk stays in real boilers when they had a weep but there was a mechanical connection to rely on. With stays pushed trough holes and soldered, there is only the "gluing" effect of the solder to trust. Not really a good fix.

RET
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by RET » Thu Jan 04, 2018 9:31 am

Hi,

One thing I didn't really cover properly is that we didn't just momentarily raise the pressure to 200 psi. but I pumped to hold that pressure for 5 minutes. While I would expect any weak points to show immediately, it is possible that some might not; so that's why we maintained that pressure for that length of time.

Given the way the boiler is built, as I said before, the worst thing that would have happened was that one or two of the firebox stays might have let go. Yes Steve, I know some of those firebox stay solder joints aren't the best, but they still passed the hydraulic pressure test. On the other hand, while you can't see them properly in the pictures, the main boiler shell solder joints are VERY well done, so that's why I wasn't worried about any gross structural failure.

If one or more of the stay joints had failed, we would have drilled out the offending stays and replaced them with appropriately sized copper rivets with the head on the inside and a long enough body so that the "tail" of the rivet extended at least two rivet diameters past the outside of the firebox. We would have silver soldered the inside rivet head first using two torches, a large propane one for general heating and just the wash from an oxy-acetylene torch for the actual silver soldering. This way you get very good control of the process. You also have to be patient and let the heat come up at its own speed (takes at least 10 minutes or more for this to happen). It also helps if you construct an "oven" from insulating brick to help hold the heat in the boiler.

If you try to push things too fast, you run the risk of poor solder penetration in the joint which might not even be visible on the outside.

Once the inside rivet head is done, you do the outside of the rivet in the same way. The rivet "tail" that sticks out conducts the heat into the joint to make sure that the solder penetrates and flows properly. When the silver soldering is complete, you can cut the rivet tail off but Its better not to cut it flush. I learned this technique from my friend Harry Hawkins. That's how he did all his boilers. I learned a lot from Harry.

Hope this helps.

Richard Trounce.

JJG Koopmans
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by JJG Koopmans » Mon Jan 08, 2018 7:44 am

Highly interesting, thanks! Could somebody let me know what the internal diameter of the 8 exhaust orifices is of the original (1:1) locomotive? My drawing does not have that detail, thanks!
Kind regards
Jos Koopmans

Rwilliams
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Re: Union Pacific Big Boy in 3/4 Inch Scale

Post by Rwilliams » Fri Jan 12, 2018 7:26 pm

According to the Don Strack Union Pacific Utah Rails website there is a chart for most of the late era steam nozzle diameters. Many of the locomotives classes are listed showing a summer and a winter blast nozzle diameter. There is no reason listed for the change in blast nozzle diameter and therefore becomes an interesting question as to why such variations existed.

For the Big Boy classes the following diameters are shown on the chart:

4000-4019 Summer diameter 3 1/2" Winter diameter 3 3/8 "

4020-4024 Summer diameter 3 " Winter diameter 3"

Not sure what the difference in the two classes of locomotives consisted of but something had to be different. The UP was known for all kinds of experiments to see if they could get more efficiency out of their motive power.

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