Standards and practices on largest diameter for valves without a gear operator

[springwaterbr]

Hello all,

Does anyone know of specific guidelines/standards/documented best practices that specify the largest diameter a valve of a given class and type should go without a gear operator? Vendors' catalogues show that many supply valves with gear operators from 2" and up, though I haven't ever seen those specified.

How do you go about choosing the threshold over which a valve needs a gearbox?

Thanks.

 

[LittleInch]

It's all about opening and closing torque.

Higher pressure and large sizes have higher torque which becomes impractical for non gear operated manual actuators.

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

 

[springwaterbr]

Hello, LittleInch,

Exactly, it's all about opening and closing torques. But I've never seen anyone actually calculate torque requirements for a manual valve when assembling a piping specification. When I'm doing so, I just follow what was specified in previous projects.

So I guess I'm asking if, for different valve types, sizes and pressure ratings, there are rules of thumb for this kind of thing, or documented recommendations from an authoritative source, that don't necessarily include bringing out the spreadsheet and tabulating line pressures and sizes for every application.

Thanks.

 

[LittleInch]

That's because it is vendor dependant and why do you care? You can't calculate this, you test it.

What you normally specify is a maximum force at the end of a bar type actuator or outside of a wheel, which is usually 50N from memory.

You can't rely on having an operator the size of Arnold Schwarzenegger, you might have a 50kg female one.

If you go round any plant which has large bar operated valves you will often find a few lengths of scaffold pole lying close by which the operators need to use to open and close the valve (cheater bars)... Not a good plan.

So basically its experience and looking at different vendors data. Each client / operator / design house have their own standard.

I've seen vendors come back and offer gear operated when the piping spec had bar operated if they think their valve has too high a torque requirement.

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

 

[springwaterbr]

Thanks for the insight, LittleInch.

I asked and care because the piping specs the firm I work for issues specify size ranges for the type of actuator (I'm not sure if this is the norm in other countries/firms?). Gearboxes are specified for 10" and up for 150 PSI butterfly valves, 6" for class 150 ball valves, 12" for class 150 gate valves, and so on. Though we do this no one could point me to where these specific size thresholds come from, other than from previous experience. Curiosity made me post.

Thanks again.

 

[LittleInch]

Fair enough - it's always good to know where things come from.

If you're really curious, do a few sweeps of different valve suppliers online catalogues to see where they draw the line at gear operated vs handwheel or bar operated, but I have to say those size ranges look about right to me.

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

 

[springwaterbr]

I've tried doing exactly that (although admittedly not very extensively), and I've come across a pattern: vendors that supply both gear operated and handwheel/bar/lever operated valves in a wide and interlapping size range, and give tables of opening/closing torques with no direct indication of when to switch over from one actuator to another.

I'll give it another look when time allows for it.

Thanks once again.

 

[LittleInch]

The torque will then translate into a force and the 50N force is one I've seen many times, but then depends on how long the bar / lever is.... or diameter of the handwheel.

I can quite believe there is some overlap and some duplication with some sizes available in both bar and handwheel depending on which spec is used.

Depends on how strong their operators are!

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

 

[mk3223]

According to one Owner SID guidelines, the maximum force of the valve operator is up to 100 abs-force or 450N. I believe it could be typical valve the valve vendor used for the gear operator requirement.

 

[gerhardl]

On a general basis, depending on fluid and particle content, a specific valve could vary as much in actual operational torque as 1:5 or even more for one size.

A factory given torqe is always given for a specific, pure fluid, temperature, pressure and for a new valve free of wear at sealings and mechanical parts.

Of course for one plant, and one type of fluid, and also comparable operational frequence, the operational torque would be about the same for equal sizes and pressures for good maintained valves.

Increased requirements for precise closing, automation and position signals will increase demand for gears or mechanical operated actuators.

A typical example for torque variation based on design variation is BFL valves where double or triple eccentric vlves might require less force and have more precise opening and closig forces than a centric valve.

Now to examples from experience. Typical BFL, globe and gate valves for water less than 10 bar:
Up to 100, 150 and occasionally to 200- 250 mm valves lever/hand operated without gear.
At theese sizes and below: gear and mechanized operation to be considered after type of use and frequency.

Above hand operted with or without gear if practical.

I have seen a leveroperatded BFL valve in larger dimension after it got stuck and had been tried opened with help of a lift-truck. The operation was not particulary successful.

 

[HitokiriAoshi]

rim pull. turn to open. Handwheel size limitation.

Luke | Valve Hax |

https://valvehax.com/

 

[TugboatEng]

Just for fun, my friend sent me this picture of an operator on a 1" valve.

On a more serious note, as an operator of valves myself, I prefer gear operators for all butterfly valves 2" and larger because they all generally require a kick with a foot to get them moving otherwise if they're older and have been sitting. Gate and globe valves are hand operable over a much wider range. Working on steam plants he had knocking valves on the 8-10" 1000 psi valves. They had weighted handwheels you could use to bang the valve open and closed. The main steam stop got a drill motor just to save time.

 

[Nick_Gray_88]

Id suggest you could look in the IOGP JIP33 specifications for the Ball and Gate valves?
Or if you look across a few customer/End-user specifications they are all in the same ball park for min. Valve size needing a gearbox.
The caveat being if the valve is smaller it may still need a gearbox is the torque is high enough to require it...