Would anybody care to fill me in on what exactly is involved in a hyrdo test for a locomotive boiler, via a step by step procedure of some sort? For example, I know that certain things like the safety vavles have to be choked so they won't lift. I also know that there is a device that is installed on the safety's themselves that holds them closed. Does anyone know what they look like and/or how they are constructed?

Many thanks,
Brian

Some questions to consider... Does your boiler have any leaks at cold atmopheric pressure? Is it in operating condition? Has it passed a hydro in recent years? Has an ultrasound test been performed to find any thin areas?

On a restoration I worked on a number of years ago, the safeties were removed and the ends capped. Also the dome throttle valve was removed and a gasketed cap bolted on. Make sure that all the air is removed from the boiler and an easily read and dependable calibrated gauge is used. Bringing the water to a certain temperature may be required. Part of the proceedure may / will be dictated by your boiler inspector. As the old saying goes - when in doubt, don't - especially when it comes to a boiler.

There others on this board that are more qualified than myself to provide further info on this as some do this kind of work every day.

Some questions to consider... Does your boiler have any leaks at atmopheric pressure? Is it in operating condition? Has it passed a hydro in recent years? Has an ultrasound test been performed to find any thin areas?

30 years ago, we were "hot to trot" to hydro test 4-6-2 S.P. 2472's boiler. Bicentennial Freedom Train crewman Al Phillips (sp?) warned us not to leap into this. The problem is that throttle valves usually leak a little. During the hydro test, water leaks into the superhater units. Superheater units are spaghetti piping with the inlet and outlet several feet above the majority of the piping. It's almost impossible to blow water out of the superheater units afterwards, no matter how much compressed air is used. this wouldn't be a problem if the boiler was overhauled in the next few weeks. But usuallly it's many yeas before the units are removed, hydro-tested (to a higher pressure than the boiler), flipped upside down, and blown dry. Result: the superhater units corrode internally over many years, which adds a major expense to any future restoration.

Moral of the story: Don't hydro a boiler with the SH units in place, unless it will be steamed soon.

When I worked on the B&ML we would prepare for a hydro by making sure all the washout plugs were clean and tight. We used teflon tape to seal the threads, along with the threads on the fusable plugs. All the backhead valves we would lap in. As someone mentioned earlier, we would remove the throttle and cap it. On the dome, we had made a fitting with a shutoff valve with a hose leading to a bucket on the floor so when the boiler got full, the water would run into the bucket and not all down the side of the boiler. We used our pressure washer to fill the boiler, this way it was full of hot water for the hydro. I can't remember exactly, but the water must be about 170 degrees, or so by federal law when a hydro is done. Two gauges are required when doing a hydro and must read within 3 pounds of each other. We had a place behind the dome where we would connect the second gauge. We used a couple of 2 jaw pullers to gag the safeties. When the boiler was full, we would use the pressure washer pump to squeeze it. Between the pressure washer handle and boiler connection, we had the line tee'd with a bleeder hose so we could relieve the pressure when we were done. If you use this method, be very careful because a pressure washer pump puts out around 2000psi. The pressure you will hydro at will, of course, depend on the working pressure of the boiler. Ours ran at 170 psi, so we were required to test at 213psi, which is 125 percent of working pressure. When we would squeeze the boiler, I would watch the cab gauge and my buddy would watch the other gauge. We would take it up to 50 pounds, check for leaks, then go to 100 pounds, check for leaks, ect. We would call out the gauge reading to be sure the gauges were OK. These gauges were tested beforehand. Also, if you schedule a federal inspector to witness the hydro, do a preliminary hydro ahead of time to avoid any suprises.
Leverett Fernald

170 is a bit high. The code reads at least 70F and 120F max.

When did you test your staybolts and how were they tested? Did you enter the boiler after the hydro and when the boiler was drained?

You are probably correct on the temperature, as I was going strictly from memory. After observing the boiler at hydro pressure, we would lower the hydro pressure to working pressure and hammer the stays. We would then drain the boiler below the top of the tubes and go inside and hammer the braces. We would also do a wall thickness check of the dry pipe.
Leverett Fernald

Where exactly do you place the jaw pullers on the safety vavles themselves?

On our safeties, we put the forcing screw on the spindle and the jaws on the body which had a lip on it for the jaw to grab onto. This may not work on other types of safety valves, but it did on ours.
Leverett Fernald

and what type and size are the valves you are using?

Regarding the devices used to lock the safety valves, I have made some of these devices that fit around the valve body to ensure they won't slip off under pressure. Not knowing any particular term that might be more correct than any other term I've heard, I named them Popper Stopper's.
Mark D.

When we hydro's boilers on my first ship, we unbolted the safeties, and inserted a blank flange between them and the piping. Do you lock down the safeties on the locomotives just for ease or is there some regulation proscribing that method.

The safeties are locked down because the boiler is squeezed at 125%. if they are not gagged then the 125% can not be reached.

There is not any regulation that states that the safety(s) has to be removed or left on. They do have to be serviced and reset annually though.

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Many years ago, I was a MPA on a U.S. Navy steam ship. Hydros came in three flavors, 100% which was used after valve packing and flexs were replaced on the boiler's steam piping but no structural repairs had been done or if "water sides" have been completed requiring the removal of the hand hole plates, 125% any time the pressure vessel had been repaired or welded on including replacement of water tubes and/or down comers, and once every 5 years a 150% "strength test" was conducted. The safeties were gagged for the 100% and 125% (they might have been removed for the 125%, it has been a very long time ago!) but they had to be removed for the 150% test. The reason they were gagged for the 100% was to prevent water from getting into the actuating mechanism since ship boiler safeties vent into pipes, the entire mechanism was enclosed.

We never found suitable method to gag the Ashton pops on 1522, so we removed them and relace them with Schedule 80 pipe caps.
There was a hollow stud on top of the steam dome lid that was tapped and had a plug in it. We would remove the plug when we filled the boiler until water came out the stud, then replaced the plug. I always tried to have the water temp at 100-105 for the squeeze.