The Steamboating Forum

True that the large buildings that I work in are continuous running, but my issue is that the valves will not hold if used to throttle. There are basically two occasions that I use a valve, first is for isolating for repairs the other is throttling a bypass while repairing a PRV.

I have seen a gate and ball valve destroyed after one use by wire drawing because we tried to open it a little to bleed down the pressure but the isolation valve was not holding. Took less then 30 seconds and I needed to replace them (BTW sounded like a freight train 1" at 125psi). With the bypass I can modulate the valve to keep the pressure down (think 125 psi down to 15 psi) to keep with the demand, I've only had to replace one globe that failed before we tried to modulate it.

The difference might be a little leakage for the mobile system will keep it warm but maybe not enough to cause motion? For my stationary applications where I want it to cool any leakage is detrimental as it hurts.

Darned if I know why you have had so much trouble. No leakage when closed on my boat. I sometimes sit for an hour at the dock with steam up.

Also there are times when I am drifting along looking at Orcas with the engine just ticking over at less than 1/8 throttle.

Maybe you are using U.S. made junk. My Chinese crud seems to be running fine (grins).

I've had whatever junk Ross Bendixen aka unionsteam puts on his boilers ball valves 3/8" get really loose. Nothing bad happened, but vibrations were enough to make them move on their own. Just very sloppy, not confidence inspiring either.

Milwaukee replacement globevalve arrived. Looks great. Feels great. Internally the valve seat has play. I can rotate the valve in my hand and it sounds almost like a swing check.

This one is a 3/4", and I'm bushing it down to 1/2". Globes do restrict more, so this should give me more top end.

-CB

cyberbadger wrote: Nothing bad happened, but vibrations were enough to make them move on their own. Just very sloppy, not confidence inspiring either.

-CB

That's when to tighten the packing nut!

Quote: "The difference might be a little leakage for the mobile system will keep it warm but maybe not enough to cause motion?"

My experience, no leakage. I've never even had to tighten up a packing nut on any of them. It's strange that you've had that experience with them, but I have no idea why that is. It could be that they sit in one position for long periods of time at high heat and the seals have deteriorated, in other words, they were bad before any throttling or opening and closing and needed to be replaced anyway. Who knows.

A pic of an array of ball valves on my tugboat, never an issue with any of them.

-Ron

Mike Rometer wrote:

cyberbadger wrote: Nothing bad happened, but vibrations were enough to make them move on their own. Just very sloppy, not confidence inspiring either.

-CB

That's when to tighten the packing nut!

On the Bendixen boiler cheap ball valves once they get loose they tended to return to that condition fairly quickly even with tightening .

However I'm always very leary of turning a packing nut when it's not 100% clear to me if there is a chance of the valve blowing out.

My MAWP is 200. The Apollo ball valves I have on my boiler have the 250psi steam trim (The lettering on the text on the yellow handle is red if you have this option with Apollo). They are fine. I've not an issue with them other then for somethings 1/4 turn is too little for my taste. My hands like to decide to do the wrong thing sometimes, and with 1/4 turn that happens quickly.

-CB

"I use one of these 1/2" NPT Bronze Nibco globe valve - Class 300 (My mawp is 200psi) as my engine throttle."

Often valves carry two ratings, and many valves are not rated for steam service. In steam service a high temperature occurs, and valves for steam service usually are marked "SWP 125" or similar, to indicate the maximum psi in steam service, "Steam Working Pressure". Many 600 psi valves are not even allowed for steam service, often marked "600 WOG" (Water Oil Gas) or 600 CWP (Cold Water pressure, or is it Cold Working Pressure?) Does the valve originally in this thread have a steam rating?

I have been running steam systems ranging from 50 psi up to thousands of psi since the 1950s, and have never had any problem in throttling service with gate valves, globe valves, nor ball valves. On my launch I use steam rated ball valves, and while they tend to feel a little sloppy with 100 psi steam if I bought them a Home Depot (with 150 SWP marking), they have held up OK, and remain tight from leakage. The first main steam valve off my boiler is however a Crane Gate valve, 150 SWP.

fredrosse wrote:"I use one of these 1/2" NPT Bronze Nibco globe valve - Class 300 (My mawp is 200psi) as my engine throttle."

Often valves carry two ratings, and many valves are not rated for steam service.

All of my valves are swp 1.25*mawp minimum. So 250SWP or better.

My Nibco globe valves are 300 SWP.
The Apollo ball valves with steam trim (red text on handle) are 250SWP.

The new Milwaukee Globe valve is 300 SWP.

fredrosse wrote:I have been running steam systems ranging from 50 psi up to thousands of psi since the 1950s, and have never had any problem in throttling service with gate valves, globe valves, nor ball valves. .

Your mileage may vary I have 5 years of hobbyist experience and I have had trouble with throttling service as my understanding and experience improved with gate valves(Stuck wtih a pressure differential, bent the gate), globe valves(my most recent fling), and ball valves (Getting sloppy, leaking, not inspiring my confidence).

Don't get me started on injectors when I first started using steam.

The only thing I haven't had was a bad check valve.

-CB

P.S.
The Nibco Valve that left me adrift...
Globe Valve - Bronze, Class 300, Bronze Disc, T-275-B
300 psi/20.7 bar saturated steam to 421°F/216°C
http://www.nibco.com/Valves/Globe-and-A ... onze-Disc/

I went to Doughty Valley Steam Days today and watched the traction engines there. (See Anaroks Corner has a video I took)

I thought I would walk around and look at some valves, especially throttle valves on steam traction engines for reference.

I got a chuckle out of this: A valve on a valve.

If the Nibco had a valve on it, maybe I could have opened the valve to clear the condensate?



-CB

One of the other Nibcos failed closed today, steam supply for penberthy injector! The outing was successful, I continued with other injector.

Im going to remove all the Nibco valves during the winter. This is really crummy.

Ran the engine with the new Milwaukee globe as throttle, no problems, better design. The valve surface has play but is captive to the valve stem. Cant unscrew from the stem because there the valve surface isnt screwed into anythink itself, it floats constrained.

-CB