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1-1/2" steam valve stem snapped - is actuator bad or the valve?

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bkc
bkc Member Posts: 41
in Strictly Steam

In our church there's a Honeywell 1-1/2" steam valve (likely V5011N2089) from the 1950s whose stem has snapped about a quarter inch below the threads.

The valve stem easily moves up and down, so it was not stuck.

About 5 years ago I had replaced the actuator on that valve with a Honeywell ML6984 because the previous actuator had failed. The actuator is controlled by a 'typical SPDT controller' (relay driven from thermostat). It was a drop-in replacement. The ML6984 is supposed to be self calibrating and there's no travel or force adjustments on this unit.

Do you think the actuator is bad or just that the valve was worn out?

When replacing the valve does it really make much of a difference between V5011N2089 (steam service $$) vs V5011N1081 (water service $)?

The valve is always operated fully open, we run at about 3psi.

Is it worth trying to repair the valve instead? That's almost as expensive as a new valve..


here's the valve in the closed position

image.png

And mid-opening

image.png

Given the wrench marks, maybe someone repaired this valve in the past..

image.png

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 11,453

    I don't know if that old version is still available, but unless you want to try welding the threaded part of the stem back on to the valve stem (will need to disassemble and possible turn it on a lathe to get the packing nut back on there) it is time for a replacement.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,172

    I would think the actuator is defective. It would have to put tremendous force on the stem to break it. I am sure the valve can be rebuilt if the parts are available. I would suspect the actuator has a bad limit switch.

    It might be cheaper to replace the whole thing.

    You could try Kele Associates in TN. or National Energy Controls in Pa. You can google either of them.

    If it is steam you have to uses a steam rated valve. Probably rated for higher temp.

    They may have a cheaper option a ball valve for example.

  • mattmia2
    mattmia2 Member Posts: 15,067

    maybe it was out of alignment and putting a lot of side force on the stem.

  • bkc
    bkc Member Posts: 41

    Hi,

    Thanks for the feedback. With respect to the differences between the water service vs steam service valve, they are nearly the same:

    Pressure-Temperature Ratings:


    Water: 36°F to 248°F, 217 psi (15 bar). 248°F to 337°F, 185 psi (12.8 bar).
    Steam: 100 psi (6.9 bar) at 337°F (V5011N2xxx).

    Seat: Stainless steel

    Plug: Brass for water; stainless steel for steam.

    Valve Flow Characteristics:


    Water: Equal percentage (V5011N1xxx, V5011N3xxx).
    Steam: Linear (V5011N2xxx)

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,172

    If they catalog the valves differently between water and steam, there must be something different

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,172

    You have to use the steam valve. I looked it up in my Tradeline catalog. The valves are almost identical except that it says there are two types of valves. 1 is "equal percentage flow characteristic" the other type is "linear flow characteristic.

    It says do not use equal percentage valves for steam. so the N2089 is the right valve

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