Mikado first run

[southwestern737]

I finally finished my Mikado, here is a short clip of the first run.
https://youtu.be/0wJbtDSl6bQ
Brent

[Benjamin Maggi]

Link isn't there.

[southwestern737]

Ok, the link is fixed. This was the first run and it was short. The ball valve I used for the throttle failed after about 500’. I replaced the valve and branch piping, made a change to the firing valve and have run it about two hours. This is my first attempt at oil firing, I wasn’t so sure after the first run but after modifying the firing valve I think I am going to be a big fan after a little more practice. The locomotive also has a superheater, 5 elements that run from the smoke box all the way to the back of the firebox too soon to tell if it was worth the complexity, but the exhaust is very dry. This was also my first boiler build from start to finish, I have done a fair amount of tube rolling, welding, and layout but this was my first complete build, it was a lot of work but very satisfying.

[hoppercar]

I'm right behind you...about a month away from firing mine.....what kinda throttle valve did you replace the ball valve with?....I used a ball valve I got from godshalls, that's rated for steam.

[southwestern737]

My original throttle valve was a steam rated 90 degree ball valve, it said not to use it for throttling, and they were right. The problem is that there is only one end of the ball that has a seal on the 90degree valves, and the seal was Teflon so it began to flow and not let the throttle close. I fixed the problem with a straight ball valve with carbon seals, rated for 750degrees. Probably overkill but I really don’t know what the superheater is capable of.
Brent

[hoppercar]

I used the throttle valve godshalls use in there locomotives..good for 150 # steam....it's made by nibco. 585-70-66...with Rtfe seats....hope it's ok

[Fender]

I assume this has a smokebox throttle. Is the valve upsteam or downsteam of the superheaters? What is the brand and source for the new valve?
Thanks.
(On edit) I realize now the valve is throttling superheated steam, so ignore the first two questions.

[southwestern737]

The valve I am using came from McMaster Carr, it actually is rated for 550 degrees, I looked at so many that I got all the specs mixed up. It was $188, the 750 degree valve was over $600 from a valve supplier, McMasters price was actually pretty good. I am happy with the new valve, hope it lasts a long time. It is a three piece valve so easy to rebuild.
Brent

[southwestern737]

As for the location of the valve I had a very difficult time deciding if it should be up or downstream of the superheater, I chose downstream for simplicity of piping and I also thought it would be more efficient (steam would have more time in the superheater) and also not be susceptible to runaway caused by a water slug entering a dry superheater element, I also thought the throttle would be more responsive and smoother for the same reason. An upstream throttle has one big advantage, if you rupture a superheater element you just close the throttle and the leak stops. If I had room I was actually going to install a valve in each location, but there wasn’t any space and your finished running in either case.
Brent

[SteamHeaton]

My Mikado does not have a super heater. I am also using a steam rated straight ball valve. In the smokebox. I wrapped it with pink house insulation wrapped that with wire, and it has performed very well for 10 years now. It was purchased from McMaster Carr or MSC , can't remember.

[rkcarguy]

It looks gorgeous, nice build!
Teflon doesn't have a super high temperature rating and with the super-heater passes it's max temp was surely exceeded.