Butterfly Valves, Ball Valves, and Leaking 4

[Fooooks]

Hello all,

Here at our plant, we are upgrading old valves in our foam-water system for emergency fires. I do not have specs on the foam-water mixture. We currently have (6) 10" CS Full Port Ball valves with electric actuators on the pipe leading to our tanks. I have received a quote from a company who recommends installing butterfly valves with electric actuators as it would require less torque, smaller actuators, and a cheaper price.

It is a 10" double offset butterfly valve, Lug, WCB Body, 316 SS DIsc. 17-4 ph Stem, ULTRA Seat, Rating Class #150.
I also have a quote for a 10" ball valve 150#, CSXCS, Full bore, fire safe, NACE DEVLON .5/90 Dur. HNBR. W/GRAP. (reading straight from the quote provided)

This is my first time with the company getting familiar with valves. I have been in this entry level position for about 4 months.

I brought this up to our head engineer who told me to forward it to our terminal manager for his opinion. I told him we would save on going with the butterfly valve for this project, but his response was "butterfly valves leak". I have heard this multiple times from upper management, saying they would prefer a gate valve to anything else. Is it possible that they are used to gate valves that they reject another type of valve? Or is there truthin what they are saying?
From research that I have done online and speaking with suppliers, ball and butterfly valves are just as good. The engineers here are indifferent, and just order gate valves because it is what we normally do. The plant technician foreman wishes we replaced all of the gate valves with ball or butterfly. I want to build a case so that when we replace valves in the future, we get the best type possible.

Do you all have any literature on comparing gate, ball, and butterfly valves and their benefits? Is the leaking really an issue among different types of valves?

Thank you, I am looking for some better information for all three types of valves. If I need to provide more information, please let me know.

 

[pennpiper]

One point you need to consider.
The face-to-face dimension of a ten inch Butterfly will be much shorter than your old existing 10" CS Full Port Ball valves.
The full cost for the new Butterfly Valves may be cheaper that Gates Valves or Ball Valves however, there will be a significant cost involved for modifying the piping system. Lots to think about.

Sometimes its possible to do all the right things and still get bad results

 

[Fooooks]

The quote includes a custom spool piece to fit the current face to face dimensions. Thank you for pointing it out though; luckily someone here mentioned it as well.

 

[LittleInch]

Fooooks,

What you find here is a classic vendor / user issue

Given the likely age of the key people in the plant (terminal manager / upper manager), they probably base their experience on what happened when they were your age ( I sense you're in your twenties?), when butterfly valves were really not very sophisticated and had a bad reputation of leaking.

Since then the design, especially of the double and triple offsets, has improved dramatically, but the previous suspicions about them, and ball valves sometimes, takes a long time to dissipate. Many people swear by them as being great, but its hard for people to change without experience - Catch 22.

A key issue is normally that in both ball and butterfly, if you close it and it leaks there isn't anything you can do to make it better other than replace it and its seals. Gate valves, especially wedge gate valves, can be forced to close a bit more by adding muscle power to the valve handle which is what operators tend to like.... Stroking a gate valve open and closed can also remove debris from the seal.

Most valves you mention (ball, butterfly and gate) are really isolation valves, but in practice they get used to start and stop flow and sometimes throttle. As they're not designed for this not surprisingly they don't work very well when then asked to isolate. Historically butterfly valves on water systems have been used to throttle low pressure systems and hence when you try to use them for isolation the seals are knackered and they don't seal, hence their poor reputation.

Valve vendors cannot normally provide operating experience because they sell valves, they don't use them. They also tend to "rubbish" other types of valves so you end up not knowing who to believe.

Operating companies sometimes do surveys and get their own view of what works and what doesn't work, but that can prevent use of new systems and is often not a very scientific option.

In the end money talks, so your only chance to do something better is to clearly document the different options and present the different costs. If a type of valve meets the spec and cost 30% less, it's difficult to argue against it if there is no specific operating experience of that particular valve. Perhaps initially limit the "new" valves for those locations where there is little start/ stop flow and leave "critical" valves the same as they always have them.

Unfortunately these sorts of things are not very scientific and perceptions and operating experience can take a big hold over people, especially if the top people don't move around much. What tends to happen is that a new section head / ops mgr/ engineering mgr comes in with different experiences and says "why are you using ball/gate valves on this system - we've used butterfly valves for xx years in yy plant and they're fine / great / best thing since sliced bread" and lo and behold the plant starts using butterfly valves(!)

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

 

[Fooooks]

Thank you LittleInch,
You seem to hit the nail on the head with how I feel. Vendors have been trying to sell me anything but Gate Valves. They CAN sell them, but they tell me how it's an old design, or dying valve, or difficult to operate, etc. Most of the people in this terminal have been here 20, 30, and 40+ years. So I agree, that since they have been using gate valves for most applications, that is just what they are used to.

I have heard multiple times that the design of the butterfly valve has improved greatly over the years. But the only evidence I really have for that is vendor brochures and their word, which is not very convincing to upper management.

But yes I'll present the cost options and hopefully convince them to purchase the butterfly valve quoted.

One last question, if you don't mind. Are the differences between double offset and triple offset that great? I hear that triple offset valves are zero leakage and inherently firesafe compared to double offset. If a double offset isn't "zero leakage" then what applications can they be trusted for?

Thank you again.

 

[SPDL310]

Fooooks all of the dying valve talk seems like vendor BS to me. Yes gate valves aren't very sophisticated, but they aren't going the way of the dinosaur anytime soon. The gates are likely your vendors lowest margin item, and not likely to yield orders for high priced proprietary seal and trim kits. There are a wide number of third party vendors for gate valves who will sell trim and seal kits cheaper than the OEM, and keep their prices down. Your vendor may be almost giving the BF and ball valves away to hit you on service items down the road. Are there any other options for service and repair on the BF and gate valves.

 

[Fooooks]

SPDL310,
I will certainly be sure to look for some third party repair vendors for the butterfly and ball valves. You make a good point, and while I'm sure the vendor will deliver with a product that will work when installed, perhaps they are looking to make their money on the services down the road.

 

[LittleInch]

No problem. TBH I've never really got into the design of butterfly valves, probably because none of my O & G clients seem to like them very much... There is more on this site if you search about them and maybe others can chip in, but triple offset appears to have a higher sealing factor.

However No valve is perfect and to get bubble tight on repeatable basis is very difficult. double offsets are a little more likely to fail that extreme test, but will still "seal" as well as any other type after several operations.

Triple offset seem to be mainly metal seal so that's where the fire safe stuff comes from compared to elastomer seals on the others unless otherwise specified.

type of valve needs to be matched to its duty and requirement / pressure / contents so there may be locations where triple offset is required, but double is also acceptable if you're dealing with a low pressure fire water system rather than a high pressure gas system for instance.

Only way to do it is to try them and slowly get buy-in / confidence in operation, but unless the cost difference is seen as significant then it may not happen in your location.

The other bit some places don't like is that for the wafer / lug design between flanges you need long bolts. In a fire situation these bolts expand more and cause more leakage....

Also you can't break the pipework at the valve as the bolts need something to grip onto. Sure you can buy "full body" or short body butterfly valves, but then the cost goes up.



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

 

[Fooooks]

Ok, I was just asking because if the price difference isn't too large, then I'd prefer to go with a triple offset so that we are trying out the best possible BF valve type. I would hate to have an unfortunate experience with a Double Offset, and then never be able to try them out again in the future.

Yes we will have them drop into existing ball valve face to face dimensions with a longer body dimension.

Thank you for the replies.

 

[MickMc]

If you want to drop them in to replace existing ball valves you will have to go for double flanged long pattern which are not so common but available and will certainly eat into your economic argument although I do not know comparative cost. Also one of the main advantages of using butterfly is shorter face to face dimensions therefore easier to handle and taking up less space therefore you will lose this with long pattern.

 

[Fooooks]

MickMc,
Yes I figured the short face to face was advantageous. The reason why we were quoted the butterfly in lieu of ball valves in this scenario was that the electric actuators could be sized smaller, which would be cheaper overall. It would also be a class IV shut off.

A double offset high performance butterfly valve was quoted instead of a triple offset due to higher flow characteristics.

I received a quote for Full Port ball valves for the same application and the other vendor is quoting twice the price to use full port ball valves with electric actuators.

 

[LittleInch]

Foooks,

Well let us know how it goes.

The issue over flow restrictions can be significant, more so for the triple offset due to its increased size.

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

 

[Fooooks]

I will, LittleInch.
And thank you for being so helpful. I contacted other tank terminals who use the triple offset, and they mainly use it for ESD situations and they have had no problems.

We shall see. I appreciate all the responses, and will update at a later date.

 

[gerhardl]

Hello Fooooks,

I saw this interesting discussion just now, and would like to add some comments.

a) There is (of course) high quality and low quality valves/makers of any type of valve, aim for the best (as you seem to do) with references for similar use. If BFL at least double eccentric, preferably trippel.

I agree with your reasoning so far, and would have gone for short body, double flanged valves with suitable double flanged extension/mounting pieces for comparing offers. This will make it more easy to mount and demount the BFL valves compared to ball valves without extension pieces.

b) Electric actuators sizing are depending on both necessary torque but also on necessary (allowable) maximum opening and closing time.
Necessary opening torque will probably be larger for the ball valves, and hence smaller actuators for the BFL valves.

Be sure that both types are offered with necessary over-torque, as both valvetypes might get stuck, if not operated/tested periodically.

c) As this is fire water, be sure to specify maximum allowable opening time. Both valvetypes can possibly be equipped with extra gears and multiturn actuators instead of quarter-turn actuators. This might (or might not) come out cheaper.

BFL valves are commonly used for (pure) firewater in Europe, also in simpler soft-sealing centric version.

Good luck!

 

[Fooooks]

Thank you gerhardl,
The manufacturers we are currently looking into for these butterfly valves are Vanessa and Deltech, which has a facility near our plant and makes ball valves, butterfly valves, and actuators exclusively. We currently use Vanessa triple offset for a couple of ESD situations in our facility, but we were impressed with what Deltech had to offer and decided to also get a quote from them.

I've spoken to the VP and President of Deltech and am reassured on the quality, I expect we will try them soon. Has anyone in this thread heard of them?

Our opening time is < 30s, which we specified. Yes they told me the ball valves would have a larger actuator.

Thanks for the detailed response, as usual from users on this forum.

 

[FelFrom]

I think most has been said above:

- Gate valves and Ball valves will probably be more expensive, as more material is used.
- Now switching from Ball valves to butterfly valves will need more initial pipe/fittings adjustments. (I assume the dimension are different, therefore additional cost)
- I would assume the current actuators will be recycled? (Cost savings)
- A flange ball valves from manufactures such as Vanessa, Deltech, Starfit, Hage Fittings or Swiss Fittings should be fine. I would not only look at the price when deciding on the such a large valve.
- Butterfly valves use less torque, therefore smaller actuators would be used (Additional Cost savings)
- Generally, what material are the tanks in?
- How often are these valves replaced? I assume not very often, thus a higher priced valve (Ball valve) might be reasonable

Also I need to agree with above post, gate valves will not start to become extinct.

My suggestion from all of the received information would be a flanged stainless steel ball valve, full bore.