Boiler questions

[Jack Innes]

The prop is a 3 blade 12" X 18" made by Egg Harbour.
The engine is a twin cylinder, 1 3/4 bore, 2 1/2" stroke .

[DetroiTug]

Would there be an advantage in using the extra flexible line they offer in that I need to turn 90 deg. in a short distance?

The flex line mentioned will make a 90° bend, no problem.

Secondly, the current setup is reduced at the "manifold" to 3/8" & runs through a 3/8 main shutoff valve to the 3/8" throttle valve. Would there be an advantage or disadvantage in running 1/2" to the throttle & reducing it there?

Not sure on this one, but it I would think running the steam line without any reduction in size at the throttle is the best way to go. Or 1/2" to where it branches off 3/8" to each cylinder. I ran 1/2" all the way to both cylinders on the Tug and it has not caused any issues.

In these is states that the boiler pressure should be maintained at 120 psi & that the safety valve is set at 160 psi (it is marked at 160 psi) From recent reading it seems that the safety pressure should be much closer to the operating pressure. Am I correct & what should the valve be set at.

Not sure why that was suggested. If the boiler will handle 160 and the engine runs best at 120, then I don't see an issue here. My relief valve is set at 100 and I run at 60-80. If it never popped off I'd be fine with it. He probably meant that is the target running pressure, but they will run higher and lower.

-The throttle valve seems to be a globe valve, now quite loose. What would be a good replacement type of valve.

The Steam rated ball valves work well for a throttle.

-Ron

[artemis]

... -Is there a better alternative to venting the safety valve vertically? At present, as pointed out, the vent is too small & not drained at the bottom. I can see a shower of hot water in the making. ...

Many safety valve manufacturers include a "drain" in the steam discharge side of the valve. This is usually tapped for a threaded connector to lead the discharge into the hot well.

[Lopez Mike]

I would seriously consider a shut off valve between any manifold and the boiler for safety and repair under pressure. On locomotives it is a poppet valve with good flow but positive closure. And good steam rated valve will do the job, though.

Mike

[Jack Innes]

http://i951.photobucket.com/albums/ad35 ... 81961421[b]

Thank you for the very helpful information.

I did find a small drain hole in the safety valve. I will find a line to lead it into the bilge - I do not have a hot well.

A valve ahead of the manifold would also be ahead of the safety valve which, as I understand it, is unwise.

The attached picture is of the manifold I have made. It has four 3/8"
NPT openings, one 1/2" NPT & one 1/4" NPT opening.

I will post further pictures in a reply as I am having trouble adding pictures.

I have replaced all of the high pressure lines & fittings with schedule 80 pieces. I also added a manifold on the engine which feeds the 3/8" throttled line into the two 1/4" cylinder lines at the center. I also have added a lubricator. There is a flexible line to be added. In the picture everything is just hand tight & may be a little off position.

I would welcome any suggestions before I tighten this all in place.

Is Master's Metallic Compound the best joint compound for steam?[/b]

[Jack Innes]

http://i951.photobucket.com/albums/ad35 ... 9dbf99.jpg

Current view of engine & boiler

[Jack Innes]

http://mob951.photobucket.com/albums/ad ... 1381962059

Old throttle & feed setup

[Jack Innes]

http://mob951.photobucket.com/albums/ad ... 1381962154

This is the old system, now replaced.

.

[Lopez Mike]

Yeow!!!!

Stop the presses! Tilt! Back up a couple of pages!!

The safety valve absolute MUST have its own boiler penetration. Must NOT share it with any other fitting. Must NOT have a shutoff valve.

The last strikes close to home with me as Folly, when I first saw it peeking out of the storage where it have been hibernating for a decade, had a shut off valve between the boiler and the safety valve. Kind alike having a disconnect in the brake lines of your car. Makes sense in some universe!

Hearing about the safety valve being on a manifold means that I will be spending a few minutes this evening looking closely at your photos. Who knows what other little gems you might have inherited?

[fredrosse]

The safety valve must be set to lift at or below the boiler's MAWP (Maximum Allowable Working Pressure), evidently in your case 160 PSIG or something higher. Boiler hydrostatic testing should be done annually, or after any boiler work, with 70F - 100F water only, at 1.5 x MAWP.

Running the boat with steam pressure somewhat lower than MAWP is needed to give some margin between the time when the safety valve may lift. When you stop using steam (while maneuvering or docking, etc.) steam pressure will build if you do not have fire controls, and we all occasionally lift the safety valve unintentionally, but this should be avoided. The other side of the coin is performance, and running steam pressure as close to MAWP as possible gives maximum performance, so many like to get close to the safety valve setpoint while trying to get all they can out of the machinery. My safety is set at 100 PSIG, and I run at 75-85 PSIG normally.

The safety valve discharge must be to atmosphere with piping as short and straight as practical, with no restrictions. This usually implies discharge straight up orientation. Running the discharge into the stack would be OK.