Ball valve and actuator assembly in vertical orientation (stem in horizontal direction)

[Orga78]

We are having issues lately with our ball valves - leaking via stem end.

The installation method for these valves and actuator are in vertical orientation (with valve's stem pointing to horizontal direction). We have yet to tear-down the valve and see the extend of the damage at the stem gland packing but preliminary finding is, the actuator (weighing 42kg) which is supported by mounting bracket could have exerted substantial side load to the stem causing it to tilt, and misaligned. We measured the distance between actuator and valve for top and bottom, and the difference/delta shows the actuator is actually tilting downward.

Will replacing the actuator to a light-weight type (option of 16kg, compatible torque) can be a permanent corrective measure to the above problem?

We are aware that the best solution will be to redesign the pipeline and get valve and actuator assy to be in horizontal orientation (stem pointing vertical), but may incur high cost.

 

[MFJewell]

You could also look at the mounting bracket. I have many actuated ball valves that are mounted vertically and have been in service for years without issue. The mounting brackets are quite substantial to accept the load of the actuator (most of ours are Rotork IQ/IQT range).

 

[mk3223]

Consult with the vendor of the valve actuator, who can design a support for your valve in the vertical line as suggested by MFJewell.

 

[Orga78]

We are using FESTO actuator. And the ones we have problems with ball valve stem leak, weigh 42 kg. Mounted in vertical orientation pose side load problem to the valve's stem, given the weight 42kg + gravity load (vertical force) do not help the mounting bracket to support for a long period either. Thus, 3 of them leaked about the same period upon commissioning (less than 2 years).

We do have other actuated ball valves mounted vertically but lower rating, and no issues.

We propose to replace to a light-weight actuator still remain in vertical mounting without design change, however, the vendor reserves some pessimism that side-load will ever be eliminated if mounted in vertical direction even with their lighter actuator.

 

[MFJewell]

If the actuator is allowing the stem to deflect enough to cause leaking, the mounting bracket is inadequate. Did your spec for the valves state that the valves shall be able to be mounted horizontally or vertically? The vendor may have used one bracket for all types/sizes of actuators without regard to mounting orientation and deadweight. If the vendor has reservations about changing to a lighter actuator, it tells me they are skeptical that the mounting bracket is robust enough.

It sounds like you made up your mind about changing the actuator, even though it may not be necessary. You could also look at supporting the actuator with a separate support (depending on location this may or may not be feasible). A new mounting bracket will be much cheaper than a new actuator. I would also make certain that the bracket is capable of supporting the new actuator without causing stem deflection.

Here are some of ours that have been in service for many years without issue:

 

[Orga78]

Thanks MFJewell. May I know what is the weight of those actuators?

From your photos, the mounting bracket looks thicker than what we have, and rigid too. We did address this to the vendor earlier on, however, they do not have the "confidence" by improving the mounting bracket design will eliminate the side-load, if the same actuator (42kg) is still mounted in vertical orientation. No doubt, changing the mounting bracket is cheaper than buying new actuator.

See below photos our the ball valve & actuator assy with stem leak issue:

 

[gerhardl]

Your problem is not uncommon.

A new and more solid bracket (I presueme 'bracket' is the yoke?) is not in itself a complete solution.

Other construction details to be checked in addition to bracket (yoke):

- All mechanical details on yoke and connection: fastening strength, connection pieces' strength and form, tolerance, linearity
- Adjustment of end stops and limit and torque switches
- Correct supports for pipeline (before end after valve)
- Extra, separate support for the valve
- Extra support for the actuator.

The reason for listing these obvious details is that you will often find faults and weak constructions here. It is far too easy to believe that any pipeline installed is correct installed and strong enough to be a stable bearing support for any added valve and actuator.

Valve-suppliers will generally stress that any forces from valve/actuator to pipeline, and from pipeline to valve/actuator, should be avoided by support or mechanical compensating constructions.

Too strong forces any way may influence function and wear.

 

[LittleInch]

That is some meaty looking actuator for the size of the valve and yes, the mounting bracket doesn't exude a lot of confidence.

I'm puzzled though as to where the valve supplier comes into this - normally you state vertical orientation on the data sheet and they need to take responsibility for the entire valve / actuator package??

Can they introduce some sort of flexible coupling and then mount the actuator separately? Like a pump motor coupling?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MFJewell]

May I know what is the weight of those actuators

Approximately 25 kg.

I presueme 'bracket' is the yoke?

Sort of. A yoke usually has a yoke nut that supports the stem. These mounting brackets bolt to the actuator and valve and do not support the stem.

 

[Orga78]

Approximately 25 kg

It seems our FESTO actuator is too much for the mounting bracket to support in vertical orientation. Dismantling it was quite a job though. Valve + actuator assy = 70 kg, scaffolding, chainblock, etc. Was quite a work-out the other day. Not maintenance friendly. We'll look at the 16kg alternative as the way to go now.

 

[Orga78]

Valve-suppliers will generally stress that any forces from valve/actuator to pipeline, and from pipeline to valve/actuator, should be avoided by support or mechanical compensating constructions.

Exactly what we have discussed with the valve/actuator vendor (supplier, not OEM) - to provide us details on the range of mounting brackets that would suit this heavy actuator mounted in vertical orientation. No info thus far. They realized they have overlooked this prior to commissioning and now the issue bit us. As long as we still use the existing 42kg actuator, they cannot guarantee side load is ever eliminated even with rigid stronger mounting bracket, fastening strength. Pipe vibrations, contribute to fatigue, will see the problem recurring over time.

Horizontal orientation of valve/actuator assy (stem vertical) is the best solution but not feasible to do now. 16kg is the best quick-win alternative for us now.

 

[gerhardl]

I recommend (assume) that you will look in addition into extra clamping/support of the pipeline before and after the valve to minimize vibrations and 'stiffen up' the pipeline.

Good luck!

 

[LittleInch]

Also even using a lighter actuator that mounting bracket looks like it is actually a U shape with a gap in the base? And slotted bolt holes? Compare to the photo from MF Jewell and those are complete squares - much stronger. Also think about putting the solid side vertical, again much stronger and stiffer to resist vertical loads.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Orga78]

Thanks all. Useful inputs indeed.

Just got the info from the vendor, that the existing 42kg actuator model - is already OBSOLETE. Hence, they recommend changing to the 16kg model.

We are inclining towards 16kg actuator solution, with solid mounting bracket (they did mention for the 16kg, they have a new design of mounting bracket - no illustration so far, just verbal info).