How to open a stuck butterfly valve 2

[franklin55]

We have a 24" Wafer type butterfly valve installed on the inlet cooling water line of one of the exchangers.A few days back the valve was closed for taking the exchanger out of service for maintenance purpose. After the maintenance we tried to take the exchange back into service by opening the valve, but it was found stuck (jammed). We tried to rotate the spindle by applying a large moment arm (putting a pipe wrench to it) but this resulted in the breaking of pin (used to fasten the spindle with the gate). Subsequently the spindle became free. Now the problem is that for replacing the valve we have to de-pressurize the main cooling water header which will result in the long duration plant outage (which we want to avoid). Can any body advice any solution to opening the gate without de-pressurizing the line?? A quick reply is requested.

 

[ivymike]

some butterfly valves are very difficult to move with a pressure differential... sounds like that's the case with this one. If you hadn't broken the valve, you might have had a shot w/dropping the pressure locally before opening the valve...

 

[berkshire]

I was going to suggest building a box around the pipe and filling it with dry ice to freeze the line,so you could change out the valve, Then I realized that I did not know what schedule pipe you were using, the pressure on the line, or the temperature of the water in the line.So I will not make that suggestion.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[franklin55]

Its schedule 20 pipe. The cooling water pressure is 5 Kg/cm2.the temperature of the water is around 35 degree centigrade

 

[racookpe1978]

Typically, 6 to 10 pipe diameters need to be frozen - and maintained frozen during the repair - to have the frozen plug hold. What is the source of the pressure on the gate valve?

Can you vent that pipe, secure the pump and drain it to reduce the pressure?

Recognize that you're going to have to relieve the trapped pressure between the gate valve and the plug or isolation in every event for your repair.

 

[unclesyd]

It would be extremely hard to freeze a 24" line as you have to have 0 flow at the freezing point.

Here are two things you might do, one will work and the other is an unknown.
We had an incident on a 20" wafer valve where the stem broke and disk cocked over which impeded the flow but not enough to to require an outage to replace the valve. As I recall we had a failure very similar to yours where the stem was deliberately pulled out enough to let the disk cock. It supposedly worked like the above valve.
This approach will work if you can't take an outage of the whole system. You can use a line stop, plug, like the one offered by Peterson Products. At one time you could rent the hot tap equipment.
I definately would get with Peterson to discuss your problem and the your conditions.
There are also several other companies who offer this type equipment.

http://www.petersenproducts.com/hot_tap_systems.aspx

 

[MiketheEngineer]

Can you backwash??

 

[11echo]

You could do a "Stopple by-pass", and still have the line in operation. Check out the following link, it has a nice cartoon showing how all this works!

http://www.youtube.com/watch?v=aYpaCknNz6Q

 

[JohnRBaker]

I've been resisting making this comment, but when I read the title of this thread for the first time I couldn't help but recall that old adage about the only two things that you need in your box of tools was a can of WD-40 and a roll of Duct tape ;-)

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.com/museum/

To an Engineer, the glass is twice as big as it needs to be.

 

[CaracasEC]

The root cause of stuck-up for these valve if the cooling water system is the system from the seawater intake is because of corrosion or ineffecient hypochlorite dosing system. Please check this system for to avoid this problem in the near future.

 

[franklin55]

We have partially succeeded in opening of the valve by inserting a rod into pipe through a hole made in the pipe and pushing valve gate through it. To achieve full flow, bypass was installed by hot tapping. However there is a problem if we need to close the valve in future. How to close the valve? any suggestion will be appreciated.

 

[msquared48]

Instead of pushing the valve to open it, arrange a way to pull it closed.

Mike McCann
MMC Engineering

 

[macmet]

Is this valve in service all year round?

 

[franklin55]

"macmet (Materials) says
24 Aug 11 9:24
Is this valve in service all year round? "

The answer is "Yes"

 

[DLite30]

Wow, that's hard to believe.

The stem broke when trying to open it with wrench, but you were able to push it open with a rod.

Huh.

 

[franklin55]

"DLiteE30 (Mechanical)
24 Aug 11 16:31
Wow, that's hard to believe.

The stem broke when trying to open it with wrench, but you were able to push it open with a rod.

Huh. "

The yoke from large sized valve was removed and installed on pipe near the valve (with stem going inside pipe through tapped hole).The yoke was equipped with an extended stem (which was used as a pushing rod). As the hand wheel was rotated, the stem went inside towards the gate and pushed it.

 

[KiwiMace]

I think you need to plan a shut.

You should consider adding gate valves in addition to the butterfly so that the valve can be serviced without draining down the system. Butterfly valves need to be able to open and close against the static differential pressure, and be exercised at least annually.

 

[TenPenny]

If you were able to do a hot tap to put a rod in to push the valve, you might consider whether or not you could do something similar to put an inflatable plug in, one upstream, one downstream, that would allow you to pull the valve out for repair.

Might be a completely impractical solution, but someone might be able to make it fly. The one issue I can see is getting the plugs back out, but you never know what someone will come up with.

 

[vpl]

In regard to the followup question of how you get the valve closed again:

There isn't a reliable way to get the valve closed again, though maybe you could make another hole in the pipe on the other side. Another thing to do would be to use an upstream isolation valve. More than likely, and sooner or later, you're going to have to bite the bullet and fix the darn thing. How and when you do that depends on how much it would cost for a plant shutdown of the duration you estimate you need.

One plant (midwest USA) in the 1990's had a somewhat similar situation (failed butterfly valves) on the main inlet cooling water for the plant. Their solution was to build a temporary cooling line that went from the inlet to inside the plant. They connected the temporary line upstream of a valve that could be closed. They still had to take a short outage to tie in the temporary line, but then they had the opportunity not just the failed valves, but also others in the line that were suspect (being of the same age and type).

Expensive -- you've got to believe it. But they figured it was cheaper than being shutdown for the length of time that would otherwise be necessary.

Patricia Lougheed

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[gerhardl]

..... For the next installation?... I have always promoted the sense of using double eccentric BFL valves of solid construction on lines where an unplanned shutdown caused by stuck or damaged valves will cost more than the differce in valve cost.

Why is it so difficult to get managers to understand the cost/lifetime principle and longterm view?

PS. So far Unclesyds comment and link seems the most practical apart from shutdown. I will give him a star for it.