Boiler questions

[Jack Innes]

Hello, I recently became the owner of the SL Modestine, Details are listed below.
The boat seems to be in good condition but it is questionable if it has been used in the past few years. I have a great respect for steam & need to know considerably more about these dainty boilers before I will be comfortable firing it. I have experience with larger equipment like my Case 20 hp engine.
Forgive me if my questions sound like they are from a novice - they are.

I have attached a picture of the boiler & have the following queries;

-Are compression fittings safe to use at 120 psi?

-Should the connection between the boiler & the engine be a flexible line? If so where can I find one?

-Is it practical to have the safety valve re-certified? Where can this be done? I am near Toronto, Ontario.

-Would it be advisable to lag the boiler with wood, it now has about 1/2" of insulation covered with a light steel shell. If lagging with wood, would there be a problem created by adding insulation on top of the existing shell then the wood? What insulation is best?

- Currently the method of cylinder lubrication is to put a few drops of oil in the plugged cocks on top of the cylinders at start up. This does not seem enough to me, should there be a displacement oiler feeding the steam chests?

I would appreciate any other observations or suggestions you may make from the picture.

Thank you


http://www.steamboat.org.uk/register/html/mode0393.htm]

http://mob951.photobucket.com/albums/ad ... b679a3.jpg

[Jack Innes]

Here is another picture of the boiler & engine on the Modestine;
[img][[URL=http://s951.photobucket.com/user/innco/ ... -8239-/img]

[DetroiTug]

-Are compression fittings safe to use at 120 psi?

For air they are okay, but I wouldn't trust them for steam. Best to use a flare fitting for copper, and the copper should be "K" size or refrigeration copper.

-Should the connection between the boiler & the engine be a flexible line? If so where can I find one?

Yes, and it should be an approved braided line. McMaster carr has them and they are approved for high pressure steam.

-Is it practical to have the safety valve re-certified? Where can this be done? I am near Toronto, Ontario.

If in doubt, if it appears old and has some corrosion, replace it. First thing to do though before it is fired up is perform a hydro test on the boiler. You can leave the safety in for the first test and see if it lifts at the set pressure. A good idea would be to post some pics of your plant and many here can help if any changes need to be made to make it safe. Issues like cut-off valves in the relief valve line etc. Judging by compression fittings and lack of a flex line, that would be a good idea.

-Would it be advisable to lag the boiler with wood, it now has about 1/2" of insulation covered with a light steel shell. If lagging with wood, would there be a problem created by adding insulation on top of the existing shell then the wood? What insulation is best?

You boiler looks to be a horizontal firetube. Insulating the outer shell of the boiler is definitely needed to help with thermal losses. Any way that is done is better than not having it. Wood over ceramic wool, sheet metal over ceramic, wood alone etc. Any that is added will help.

- Currently the method of cylinder lubrication is to put a few drops of oil in the plugged cocks on top of the cylinders at start up. This does not seem enough to me, should there be a displacement oiler feeding the steam chests?

The "Tallow oilers" in the top of the cylinders are really only for start up. If it's a condensing plant, then in line oilers other than one shot type are a problem as it is hard to get the oil back out of the condensate in the hot well. If you're not condensing, by all means install an inline hydro oiler.



-Ron

[Jack Innes]

Thank you for the information.

http://i951.photobucket.com/albums/ad35 ... 3a723f.jpg

This picture shows the outlet at the top of the boiler. It has many discrepancies including close nipples, compression fittings & regular looking fittings. Would it be acceptable to replace the whole thing with a machined manifold with the correct sized outlets placed in the correct directions? I have the equipment & ability to make this. Would there be any advantage of using brass or steel? This could be much more compact & would reduce the weight suspended on the boiler outlet.

The flex steam lines I found at McMaster Carr come with fittings but have a minimum length of 5'. Am I looking in the right place? The line I need will be about one foot long.

The boiler is a Blackstaffe water tube type.

[DetroiTug]

For the braided line, have a look at this one:

5680K13

It's 12" long and rated for 1250° and 1186 psi at 72° There is no rating for pressure at 300° Anyways, they are US made and that is the type that most use and I've never heard of one failing. My guess, that is lawsuit wiggleroom. Grainger sells them too.

Yes, I would replace all of that as it appears to be schedule 40 fittings and there is a quite a bit of weight suspended on the boiler outlet. Don't have to, but one should try to use schedule 80 series 300. The cross section of the threaded portion of sch40 pipe is scary thin in the thread root. A manifold would be a good idea, and support it somehow off of the boiler. And include it in the hydrotest. Of course it's integrity will be solely dependent on it's design. Also the vent on the relief valve appears to be too small. If that's a 1/2" valve then the vent should be 3/4" pipe with no smaller inside diameters anywhere to impede the venting.

-Ron

[barts]

One inexpensive source of very rugged fittings is hydraulic components. These 3000 psi fittings are steel, and are widely available and used. You can also find male tees, etc, that are not otherwise available.

- Bart

[Jack Innes]

Thank you Ron & Bart. The 5680K13 flex line will be perfect.

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?

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?

Jack

[johnp]

Hi Jack

Congratulations on the purchase I was at Nola's and looked at that boat, but was interested in one of Malcolm's engines. There is a company in Concord called Nitro industrial sales that sells those flex lines. I buy a lot my fittings valves etc from them. There is also McKay boiler supply in Woodbridge where I buy insulation, gauge glass etc.

[Jack Innes]

John, It is good to find someone nearby with experience. I am sure we will be in touch.

I have yet more questions;

-The builder of the boat recorded a fine set of instructions & details on the boat which is very useful. 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.

-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.

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

Thank you again for the good advice,
Jack

[Mike Rometer]

The required pressure to operate could vary according to the load. Lightly loaded 120psi may well be enough to satisfy the requirements, heavily loaded needing a bit more.

Is the prop tall enough?