Hydro Test

[Builder01]

Actually, GWRdriver and I agree about an initial test for new boilers. All fittings are usually removed and bushings plugged, except for the hydro test pump, (usually a hand pump), for the 2 times working the pressure for a new boiler. This test is to prove the soundness of a new boiler, not the fittings.

David

[Fender]

Nowadays, full-size locomotive boiler inspections include ultrasonic thickness testing at least every ten years. Back in the day, this wouldn’t have been possible. How much has this affected the way boiler inspections and hydrotresting is done?

[Builder01]

Nowadays, full-size locomotive boiler inspections include ultrasonic thickness testing at least every ten years. Back in the day, this wouldn’t have been possible. How much has this affected the way boiler inspections and hydrotresting is done?

I think ultrasonic testing of full size loco boilers is done after a certain number of operating hours. I saw a boiler at the Strausburg railroad being readied for this procedure. While it is interesting, it changes nothing for the testing of miniature boilers.

David

[Marty_Knox]

Nowadays, full-size locomotive boiler inspections include ultrasonic thickness testing at least every ten years. Back in the day, this wouldn’t have been possible. How much has this affected the way boiler inspections and hydrotresting is done?

It is 10 years in Great Britain. Here, it is 1472 service days OR 15 calendar years, whichever comes first. A warm water hydro and a steam test is required before putting the locomotive back in service. Hydrostatic test to 125% working pressure is required every year.
At Ridge Locomotive Works we do an initial hydro test to twice working pressure, and provide the customer with a copy of the 'birth certificate'.
We also provide material specifications and some basic stress calculations.

[Fender]

David,
I see no reason to not subject our boilers to ultrasonic testing. Not as a substitute for a hydrotest, and not as a regulation, but as a means for the owner to check the condition of their boiler, and estimate its remaining life. The testing devices are relatively cheap.

[Marty_Knox]

I use my ultrasonic thickness tester to check the firebox, especially the crown sheet.
When someone brings me a boiler to retube first thing I do is have it sandblasted, then I UT the firebox. I have found sheets that were 5/16" to start with that have thinned down to .110".

[Builder01]

Sure, I see no downside to ultrasonic testing on miniature boilers. It would be something beyond what most clubs require of boiler testing. Certainly nothing to lose by doing this. As a requirement on full size boilers, the upside seems pretty obvious.

David

[kenrinc]

For miniature boilers, newly constructed boilers are hydro tested to two times the working pressure. New boilers that are taken to the 2 times working pressure, usually have all fittings removed and all bushings plugged except the one going to the hydro test pump. (A hand pump works fine for this) Subsequent tests are done at 1-1/2 time the working pressure, this is typical for the annual test. Most live steam clubs use these pressures for newly built boilers and annual tests for existing boilers.

Just an observation. When I went through this process as a newbie, it was semi confusing. I had my boiler built by someone else, the builder hydro tested the boiler as part of his build process. I did a reduced hydro test just for my own learning and to check for leaks when I received it. There were no leaks. Boiler held pressure with no issue. I asked the club if they wanted me to bring the boiler for hydro and received a "we don't do it that way". Bring the finished engine and we will do a hydro. OK. I then built a locomotive with that boiler and piped and installed all the fittings. Upon first hydro at my club, the boiler inspector was "concerned" with the fact that the boiler didn't hold pressure due to all of the slight leaks (throttle, turret, etc....). The boiler past the hydro it just didn't hold pressure. Upon steam up the boiler has no issue holding pressure. I've found upon watching other hydro tests that other engines are the same way.

$.02

Ken-

[Bill Shields]

It is very rare for a piped up boiler to have zero pressure loss ASSUMING that all the air is out. Experienced inspectors are not concerned about this as long as there are no leaks where they are not expected.

[Builder01]

kenrinc

"we don't do it that way"

Well, that certainly is interesting. It's hard to know exactly what was going on inside the inspector's head, but, what I have described is a pretty typical procedure for miniature railroad clubs that run live steam. Sorry about your experience, but, it sounds as if everything is okay. Being that your boiler was built for you by someone else, usually a boiler builder will give you some sort of certificate of hydro test, I assume you presented this to your inspector.

It's possible that the inspector did not understand that your boiler was new. New boilers usually require not only a 2 times working pressure hydro, but, also a visual inspection of the boiler off the loco frame, while under hydro pressure, and without cladding.

For the annual test of 1-1/2 time working pressure, this usually allows for leaks at fittings but not for structural places like tube sheets and stays. The pressure is maintained with the hydro pump at 1-1/2 working pressure.

As Bill Shields has alluded to, inspectors know the difference between structural leaks, and leaks at fittings.

David

[pat1027]

How reasonably priced ultrasonic tester is suitable? I see a unit from Dwyer (a name I know) for $270. The no name models on Amazon for less than $200. Then they march on up over $1000.

[Fender]

I bought mine (Signstek brand) for less than $100. The device displays thickness in mm, so one has to divide by 25.4 to get inches. It comes with a “coin” of known material and thickness, so you can calibrate the device. Note that rust or paint can give erroneous readings, so the surface must be clean. I use a drop of glycerine on the sensor for good acoustic contact. Also, the device is calibrated based on the speed of sound through steel, so a different reading will be given on other metals.
I would not expect such an inexpensive device to be used to certify anything for commercial purposes. Rather, it allows the user to monitor thickness in a non-destructive manner, and confirm inspections done by other means, on their own equipment.