Reflex gauge

[Lopez Mike]

My experience with steam boiler practice is pretty strongly biased towards locomotive practice where the manifold has its own shut off valve so that you can work on any of the various things that take their pressure from the manifold without shutting down. In that case, obviously, the safety valve couldn't connect to the manifold.

This boat was built by an older gent who A: had no contact with the steaming community and B: passed on before he had a chance to blow himself up. His son managed to cobble together enough temporary piping to steam it for about two hours before it went into storage for a decade. I bought it for a song. And named it Folly.

The hull is problematic. Dunno whether to try to put some lipstick on the pig or just plant flowers in it. The engine and boiler are new and good stuff. I have a fifty pound box of cheap piping and valves that I removed from the power plant. I am ready to plumb another house!

For me, the only things that I am prepared to connect to my boiler without shut off valves are a water column, suitably overbuilt, and the safety valve. Everything else has a schedule 80 nipple and a proper steam valve. I have other things to worry about such as navigation and people falling overboard and tooting my whistle at pretty girls.

Mike

[barts]

While it's fine putting it out into the public domain you are confident in a non-standard repair on your boiler, stating you won't have a problem as you won't be far from shore doesn't instill confidence in any potential steamboaters who may be thinking of joining our hobby, or indeed thinking of buying a steamboat made entirely by it's previous owner.

Non-standard repair? I designed and welded this boiler myself - there is no "standard" here. The boiler's copper tubes are part of the pressure as well; they're type K copper 1/2" in diameter. The heavy bronze castings that form the reflex gage, and the very heavy glass therein, are far more robust than the thin copper walls of the tubes. The risk is one of personal injury if the glass breaks - but we have lots of folks w/o simple shields on traditional sight glasses which are far more likely to break. Yes, I can add valves to allow shutting off the sight glass - but this will not materially improve either safety or reliability.

Anyone who ventures out in a boat MUST weigh the consequences of gear failure, whether that's sailing rigging, a boiler or a 120 year old crankshaft casting. Things go wrong... and in nearly 30 years of steaming, I've seen plenty of problems that have disabled boats... blown boiler tubes, plugged fuel lines, broken fuel pumps, destroyed gearboxes, etc. Even boats that ran low on fuel. I've towed in both disabled steamers and gas boats.

- Bart

[barts]

Otter's safety valve is connected to the boiler via a (non-isolated!) manifold; the same 1/2" boiler connection provides the top connection for the reflex gage and the pressure gage.

I am at a loss to figure out how this affects safety. Yes, the boiler level as shown in the gage will be unreliable while the safety is blowing... but since the water level would rocket up 6" due to bubble formation anyway, this is academic. The pressure gage is fine connected there as well....

- Bart

[Lopez Mike]

I suspect that the strictures against sharing the safety valve with anything else are due to idiot designs where the passage from the boiler to the safety valve is restricted in some way. You wouldn't believe the stuff that wanders into my shop from time to time!

Let's see. Who was it that made a design mistake that kept his sight glass from reading right? (grin).

What I think about on long evenings is what incredible blunder I may have made that I don't know about (yet!)

Good judgment comes from bad experiences. I'm hoping to have the bad experiences be someone else's.

Mike

[steamboatjack]

folks
I agree with everything Greg says except the bit about the safety valve, I cannot find a specific regulation in the UK regarding fitting a safety valve in common with other components but it is common practice to fit the safety valve separately, I cannot recall having seen a boiler which does not comply and I would be questioning any such arrangement.

Regards
Jack

[DetroiTug]

Not trying to argue, simply trying to understand. First one poster states the use of globe valves should not be used as they prevent rodding through, and another poster states that gate valves should not be used as they are not 100% positive shut-off. I'm showing my ignorance here possibly, Other than ball valves, what other types are there? Tapered valve?

-Ron

[Mike Rometer]

Don't confuse globe valves with ball valves. What is required is a quarter-turn valve that gives full bore on open (so you can rod through). That can then be shut very easily and quickly should the glass break, even by throwing a cloth over it. Better class ball-valves have PTFE seats, and are very long lasting. The other sort are taper-cock valves that can be a pain for leakeage as they get older, though they can be reasonably easily re-seated.

[Lopez Mike]

I'll have to think about the idea of ball valves. It sounds great to be able to clear the passages when the valves are in the open position though I have never had any problem with significant crud buildup in my boiler piping. And I am using those valves in several applications now. They work very well.

The problem is that my tubular gauge has some features that I like. First of all, the passages are fairly restricted so that, in the event of the glass failing, the steam flow is restricted. Second, there are flow check valves that close off the passages if the flow exceeds some level. Small balls that jump into the flow path.

It's hard for me to see how I would incorporate these features in a home made gauge assembly. I guess the idea is that with a reflex glass, a catastrophic failure is largely eliminated, thus the small passages and check valves aren't needed.

I am looking into hydraulic unions for a quick way for quick disconnects at several points. When I trailer for longer distances I not only drop my stack, I also disconnect my whistle. And when I cover the boat when stored in the yard under a tarp, I disconnect the safety valve and main steam pressure gauge. The unions I have now are ordinary plumbing unions. They aren't rated for this service and are butt ugly. Perhaps the hydraulic units will be an improvement. They would certainly take the pressure!

Mike

[fredrosse]

Steamboatjack wrote in his 12 Nov 2012 post here : “The picture showing a water column:- I have two comments here, first the gauge looks to me like one I would use on a water tank? “

ANS: This is an Ernst Steam Boiler Rated 300 PSI bronze gauge glass assembly mounted on the boiler water column. The Ernst Gauge glass assembly has isolation valves top and bottom, safety balls which instantly stop steam/water flow in the event of gauge glass breakage, and a small gauge glass blowdown valve at the bottom gauge assembly.

“Second, the connection between the column and the boiler should also be fitted with isolation cocks to allow “cross blowing” and the column should have a drain cock. The arrangement shown would not be allowed on a ship.”

This boiler is built in accordance with the ASME Code, and the Code allows water columns with no isolation valves. According to the Code, the water column connections must be much larger than the gauge glass connections, thus less likely to plug up. While in service, the Code requires any valves in the water column to boiler path must be locked open, and each valve must have positive indication of valve position built into the valves. For me it has been easier to simply take down the unions for cleanout as needed.

As to the water column drain valve, one is fitted on the column as well as the gauge, but the picture you refer to was taken when the boiler was being re-assembled after new burners were fitted, and that valve was not screwed on until after the boiler was bolted into the boat. Both the water column and the gauge glass are regularly blown down.

Steamboatjack's point about cross blowing the water column connections is well taken, and I will soon have a method of doing this without taking down the unions. I will now make a high pressure water lance which can be inserted from the top plug of the water column, and direct the jets through the short pipes between the column and the boiler proper. It will be fairly easy for individually blowing these paths, and blow clean these short pieces of pipe with a high pressure (2500 PSI) water jet.

[fredrosse]

Mike, "looking into hydraulic unions for a quick way for quick disconnects at several points"

I don't know what these unions look like, but two technical points to consider:

1. Do these Hydraulic Unions have the temperature rating necessary for the boiler?

2. Is the material right? The ASME Code has many pages devoted to allowable materials, and uses of various alloys being "Permitted" or "Non-Permitted" for boiler service. Boilers have special requirements, and the Code certainly makes distinctions, often just using something made of "steel" will not be right for a boiler. I have no idea if these Hydraulic Unions would qualify, but would suggest you consider Code approved materials, fittings, etc. For our relatively low pressure boilers, ASTM SA-105 steel fittings are good according to the Code, (Ratings available, 150 PSI, 300 PSI, 600 PSI, etc.) and available at most larger plumbing houses.

I know many think I go "overboard" (woops, was that a pun?) with the Code stuff, but I think it is better to comply if you can, especially if the cost might be small compared to the potential consequences.