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phil burman
08-17-2001, 07:15 PM
Yes but you should test at a pressure that is significantly higher than the maximum operating pressure. In pressure testing pipelines it is not uncommon to test to "yield". This technique actually removes defects.

Phil


<font face="Verdana, Arial" size="2">Originally posted by gmatov:
You know, if you put whatever pressure you test at, and the vessel stays at that size, you just might be setting up a burst in the future.

If you test and the vessel doesn't come back to near zero, with indicators all around it, it has stretched, and it will stretch the next time you get to that pressure, and more the next time, till you get a burst.

You are talking minis, so a "little" bomb, but still.

Have to go look at my big train book to see what working pressures were, but they were not very high in the early engines, large pistons, yes, area was good enough for the metals they had.

Pressures were relatively low. When they went too high, big bomb.

Make the vessel of the best metal that is realistic.

Cheers,

George

Get a hydraulic Porta_power jack, clean it out of the jack oil, put water in it, put a guage on it, and if you need, a pressure regulator. It will make all, or as little, pressure as you need. 20 bucks or so.</font>

billyboy
02-27-2006, 01:16 PM
has anyone any ideas/drawings of how to make a water pump to deliver around 100-150 psi of water into a model boiler, ive made the boiler and fixings and the boiler at the moment is in an un-soldered condition, i just need a way of delivering the water upto this pressure. any ideas please?

thanks bill

SGW
02-27-2006, 01:24 PM
This has probably been disucssed in back issues of Live Steam magazine, since there have been numerous locomotive construction articles over the years and this problem would have (or should have) come up for every one of them.

An e-mail to Neil might yield some results.

railfancwb
02-27-2006, 02:36 PM
Any hand operated boiler feed pump with check valves on the water and boiler sides should do the trick. Doesn't take much water volume from the pump to bump the pressure up once the boiler is full of water if there are no leaks. I use the hand pump in my loco's tender...

Charles

hitnmiss
02-27-2006, 04:34 PM
I built a simple pump with o-ring for piston rings and one-way check valves with stainless balls. Worked well, much easier than I thought. In fact my boiler has a 60psi safety valve and I was testing to 120... On the 1st hard pump on the handle the pressure shot to about 200psi

hmm, 100psi isn't that much. Maybe fill a rubber air line with water, fit to the full boiler and squeeze the line in a vise?

Al Messer
02-27-2006, 09:03 PM
You can do it without a pump IF you're VERY careful. Fill it completely full of water--no empty spaces at all. Plug all openings except for the pressure gauge connection. Then, with a Propane torch, very gently heat the boiler shell. It does not take very much increase in temperature to send the pressure zooming upwards. This is NOT a Steam test so don't keep the heat on it too long. After it has successfully passed this test, you can give it a proper Steam test.

Al Messer
02-27-2006, 09:05 PM
P.S. Bill, haven't you found a local model engineering or live steam club yet?

TECHSHOP
02-27-2006, 09:29 PM
At my old work when a single wall tank got "sucked in" (think the can on the stove science trick, scaled up to 1500+ gal). We filled it with water, sealed all the openings, and added some "plant air". When the dents popped (mostly), depressurize. This was with automated pneumatic valves, and a safety valve, with nobody close if the damn thing went "BOOM".

------------------
Today I will gladly share my experience and advice, for there no sweeter words than "I told you so."

charlie coghill
02-27-2006, 09:42 PM
For my pump I used two check valves with flow going the same direction. The check valves were screw to a 1/2 pipe "T".

From the intersecting connection on the "T" a 1/2 pipe nipple was screwed in. A packing gland was welded on the end of the nipple. A piece of stainless steel is used for the ram and a lever connected to the ram.

The end of the lever is connected to linkage and the linkage is connected to some sort of base.

You conld also add a pressure gage down line some where.

barts
02-27-2006, 11:00 PM
Do it like Charlie described... I've used 5/8" stainless rod
running in 1/2" brass pipe for years on "Otter", our 19'
steamboat. Works like a charm, all you need is an
O-ring groove in the end and a tee and two checks.

- Bart

Kansas_Farmer
02-27-2006, 11:05 PM
For our hydrostatic tester, we have a small pressure washer pump electrically driven with an inlet globe style 'variable restriction'( I realize that most people call these valves, but a valve implies that it will actually shut something off, since globe valves never acutally shut anything off, it's a variable restriction) a relief ball that allows the water to return to the inlet side of the pump, a pressure gague on teh outlet side with a needle/seat valve on the outlet. This allows us to use city pressure to fill the boiler with, hit the pump and close down the outlet side when we get the right pressure on the master gauge to use.

Al Messer
03-01-2006, 07:10 PM
Bill, if you don't mind sharing the information, just where do you live in England? I know some gents there that could probably help you a lot with this boiler project.

Scottike
03-01-2006, 09:09 PM
I'm no steamer, but for testing, I would think an air over water setup would work.
fill the boiler with water, and run a hose to a small resevoir half full of water with a valve to release pressure and hook an airline to the top. Use the regulator on the air compressor to regulate the test pressure. Like I said, I'm not a steamer, so maybe there's a problem with using a setup like that for what you want to do.

Kansas_Farmer
03-02-2006, 08:51 AM
Scot,

It would work I think. I dunno if I'd be too keen on passing a boiler that was tested that way, simply cause I've never done it that way before. In theory it should be fine though.

Evan
03-02-2006, 10:03 AM
"At my old work when a single wall tank got "sucked in" (think the can on the stove science trick, scaled up to 1500+ gal). "

Heh. Don't close all the valves after steam cleaning....

http://vts.bc.ca/pics/tankcar.jpg

SGW
03-02-2006, 11:36 AM
I bet you could easily get the pressure you need with a grease gun -- just put a Zerk fitting on the boiler.

cam m
03-02-2006, 04:28 PM
SGW
No kidding! We routinely pressure test welds with grease guns. Amazingly enough, if you put your mind ( and arm ) to it, you can get up to 2000 psi from the common grease gun. The item we usually test has a void space that takes most of a cartridge of grease to fill, then the pressure increases sharply. The issues we have are: 1.) the zerk often leaks back through the ball, or 2.) the repair is very difficult to do because you've filled the leak with grease....

Kansas_Farmer
03-02-2006, 11:06 PM
Yup, grease guns work nicely for that. I've fabbed up some spark plug adaptors for them. Pull the VC off your stuck antique engine, loosen up the rockers, remove the spark plug, fill with diesel, attach specail plug with zerk, apply grease gun. It'll either turn over, or the block will crack. I usually stop at 1800 psi.

gmatov
03-03-2006, 01:13 AM
You know, if you put whatever pressure you test at, and the vessel stays at that size, you just might be setting up a burst in the future.

If you test and the vessel doesn't come back to near zero, with indicators all around it, it has stretched, and it will stretch the next time you get to that pressure, and more the next time, till you get a burst.

You are talking minis, so a "little" bomb, but still.

Have to go look at my big train book to see what working pressures were, but they were not very high in the early engines, large pistons, yes, area was good enough for the metals they had.

Pressures were relatively low. When they went too high, big bomb.

Make the vessel of the best metal that is realistic.

Cheers,

George

Get a hydraulic Porta_power jack, clean it out of the jack oil, put water in it, put a guage on it, and if you need, a pressure regulator. It will make all, or as little, pressure as you need. 20 bucks or so.

#66B
03-03-2006, 05:38 AM
I use a Porta-Power Pump, with oil in it, if testing with it clean full of water, it only takes about a teaspoon of oil to reach 2000-2500# I use this method all the time pressure testing bottles & fixtures for gas well & pipelines that we build. Just using the pump & watching the gage, you can stop at whatever pressure you want.Good Luck & be careful.

Kansas_Farmer
03-03-2006, 12:33 PM
Yup, and everytime we put a fire in them they heat up, and expand, and then cool, and contract, and that fatigues the metal even more. Soon after that, it'll be to weak to stand the pressure it did in the past and we're back to it blowing up.

If' we'd known then what we know now about metals, and had the ability to see with the detail we can today back then, we'd never have built anything steam powered. It's a wonder that any of these old engines built back in the 1890's to the 1920's are even still together for as many times as they've been fired and worked.

The fact that there ARE plenty of them still together says that some people worry way too much.

cam m
03-03-2006, 03:52 PM
First off - I know nothing about boiler tests, But.... Isn't the hydro test done at some level well above operating pressure? Most pressure stuff I know about call for testing at a minimum of 125% of the maximum operating pressure (MOP) - the regs for some applications call for double the intended working pressure. If that is the case, the boiler should only see the test pressure at re cert time and never see it between unless the pressure relief valve(s) fail.
Cam

[This message has been edited by cam m (edited 03-03-2006).]

Kansas_Farmer
03-03-2006, 03:58 PM
Yup, 125% is the number most regs use and is what we use in our traction engines.

TECHSHOP
03-03-2006, 11:39 PM
Evan:

Your pic has it about right. You would have to stand it upright on four legs, like a silo. Usually, happened when the boiler "shot steam" instead of hot water through the lines. If a sight glass didn't give, the stainless steel does. It wasn't something the operator could hide until after shift change or blame on the prior shift. Man, I do not miss working at that place at all, but truefully that only happened two or three times a year.

------------------
Today I will gladly share my experience and advice, for there no sweeter words than "I told you so."