Thank you all for the input on my question below. And I want to let you know that I agree with all of you. I have alot of respect for steam and I know its potentials.

If I may get a bit more specific, If this same locomotive boiler is hydro tested and it "passes"
why would it then be unsafe to build steam pressure in it well under the hydro test pressure but enough to move the locomotive?

I was under the assuption that a hydro test tells you more than if the boiler leaks or not, I thought it tells you more of its ability to hold pressure overall. Am I wrong?

Thanks
Alan

adofmsu@aol.com

Not only wrong but DEAD wrong.
With a design factor of safety of 4.0, a 1/2" plate need only be 0.126" thick theoretically to NOT fail under a working pressure hydro test.
Furthermore, in addition to just pressure stresses, as the firebox expands under heat, induced expansion stresses can sometimes exceed pressure stresses. A boiler part sees the expansion stress PLUS pressure stress, simultaneously.
Please be alive and enlightened and not dead.
The photos shows a boiler that passed a 225 psi hydro six months earlier and had a valid CA permit when the photos were taken.

To pose a reverse hypothetical--why, given the risks involved and the common agreement by all reasonable authorities on what constitutes safe and responsible steam restoration/operation practice, would one look, hypothetically speaking, for a way around doing the right (and legal) thing? One might conclude that the people working on the engine in question know what they should do, but are looking for a reason or justification not to do it, and to do what they want to do instead.

Just hypothetical, mind you... :-)

eledbetter@rypn.org

As I see it, people, like nature tend to take the path of least resistance (the easiest and cheapest way out possible). That, mixed with a degree of ignorance concerning even basic boiler physics can lead to negative outcomes or at minimum be financially painful to rectify. Or they arrogantly think, "it won't happen to me (or those nearby)".

It all gets back to "pay me now or pay me later". Usually, "later" is a lot worse.

Laws shouldn't be the only reason to do the right thing.... how much is a good night's sleep worth when you know what is the correct thing to do, and you didn't?????

Don't underestimate the ignorance of many large dreamers out there without resources to do the job correctly who assume things without real facts.

An educated guess is one thing but the impressions of a novice - and only a novice would try this sort of thing - is quite another set of circumstances. There are a few of us have-tools-will-travel guys with experience out there to draw from but we have our own expenses and we have livings to earn. The cost of hiring expertise can break a project that otherwise appears feasable to inexperienced but goal-driven people.

Other considerations include the standards maintained in the last days of "real steam" which were not high. Our last remaining old timers may not have learned any but the stopgap measures to get another trip out of her before the new diesels arrived. This scenario was responsible for a not tragic but embarrassing crown sheet incident in a large state operated museum some years back.

Many of our state and local inspectors are the same folks responsible for amusement park rides, elevators and escalators, etc and have therefore little familarity with high pressure steam boilers. Inexperienced operators may take the word of these uneducated inspectors that all is well without any real testing and professional inspection. There are some old engines running at some parks now that scare me as a result of this scenario.

I don't think a complete Form 4 is the only road to safety but a competent inspection and calculation of some sort, or at least verification of documented construction standards is required minimally before firing up an unknown commodity.

Dave


irondave@bellsouth.net

Im asking what you learn from a hydro test. and why would it be unsafe to put 40-50 psi in it to see if it would run a few hundred feet.
Yall are reading alot into my posts. Im not looking to skirt the law or even avoid the safe and best route. Im not trying to start a tourist line using an unrestored park engine.

I know that it would be extremely unsafe and foolish to fire up a steam loco without checking its integrity..

adofmsu@aol.com

Hi Alan;

(Simplifying things a bit)

The nice thing about putting water inside of a container and then putting it under pressure is that if the container ruptures, a little bit of water comes out.

Now, air, and especially steam, is a different story.

Think the difference between popping a water balloon, and one filled with air. The water balloon simply, well, splats water. The air filled balloon will either make a big pop, or go flying around, driving all the dogs in the area nuts... :-)

Now, imagine that difference, but scaled up incredibly in both size and pressure, and remember that while the material that a balloon is made of is soft, so won't hurt, steel is not.

The hydro test tells you (or, should tell you) whether you can trust your boiler, without harming you.

> Im asking what you learn from a hydro test.
> and why would it be unsafe to put 40-50 psi
> in it to see if it would run a few hundred
> feet.



john.stewart@crc.ca

Great analogy! thanks John

adofmsu@aol.com

While every loves to see a locomotive run ASAP, some very logical and important tests need to be done to safegaurd people and do no harm to the machine. While this IS NOT the complete list for every boiler, it should serve the basics for how to get from here to there.

A thorough internal and external visual inspection of the boiler is done for glaringly obvious things like rotted out tubes, sheets, braces, rivets, bulges that should tell you to look even deeper, etc.

The next thing one could do is to remove the throttle valve and cap the drypipe and verify the staybolt telltales are cleaned, wash out from the boiler what is loose, then fill it with water to see if and where it may leak from by gravity alone like broken staybolts, seams, tubes. (The locomotive I worked on, at the initial filling produced a shower from the broken staybolts. One of the guys was shoving welding electrodes in the the tell tales so the leaks wouldn't exceede the water supply before the boiler was filled).

This next step I feel shouldn't be attemped until a professinal locomotive boiler consultant if possible, and a real boiler inspector from the state or insurance compnay has been contacted for direction and help with applicable paperwork. They need to be part of everything that happens from now on if you want to run it and do it right.

Assuming there aren't any leaks at this point, the boiler should be dry and Ultrasonic testing done to help determine if it can even be pressurized and to what pressure.

Once the calculations are done, a hydro can be attempted. This will show where leaks occur under cold static pressure.

While a hydro does cause a some amount of movement and stress on the boiler relative to firing it off, the pressure can be relieved almost instantly if all the air is removed as it should be. Nobody gets burned or scalded while the boiler is gone over with a fine toothed comb as the pressure is increased. Once the predetermined pressure goal is reached, the valve is shut off between the pump and calibrated pressure gauge on the boiler to see if and how quickly the pressure does drop. If it drops a leak is present and an investigation should be done.

Once this has been done for in house testing the boiler inspector should and will be there for a final hydro before he gives the blessing to fire it up.

A word to the wise is to use appropriate plumbing for the pressure being achieved.

I haven't been around as long as others working on steam, but I've had my share of experience with a number locomotives and other steam machinery. I wouldn't attempt a hydro or restore a new specimen on my own. I know enough to find someone with MORE experience than myself to work with me OR LEAVE IT ALONE.

Many hydros may be required as repairs are done until the goal is reached.

Please add to my list what I may have missed.

A hydro won't show you a thin spot that is scaled over. How thin? Well, for example, if you weld a thru stay into the heads of an ordinary aluminum beer can, it will deform, but it won't fail till well over 125psi....
There are several horror stories of boilers that passed a visual, AND a hydro, but the belly of the barrel was later punctured (thank god they were cold at the time) with chipping hammers, or even common screwdrivers.

Any inspection is only as good as the fellow performing it.

I agree fully that a hydro is not the do-all-to-be-all, but if it is the ONLY test beyond visual inspection, it will only tell you it holds cold water at X pressure. You still need to do physical measurements to determine MAWP which goes hand in hand with your "how much" question. Nobody can see a cross section of a boiler plate that is not a sheet opening for plumbing or handholes. A hydro is but a step in the process to return a boiler to service, not the final word. Also, it won't tell you what the physical quality of the sheet material is. If it was built or repaired with substandardmaterials, the hydro will only show it did or didn't fail.

John,

Yesterday I was writing my response below as you were posting yours. I had no plan or intention to make it look like I was trying to up-stage your message. I ran out of time to write.

Ray