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Thread: Damaged stop valve
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30-12-2015, 07:28 AM #1
Damaged stop valve
This is an interesting one, a Danfoss 100mm stop valve installed in a discharge line header close to inlet of condenser.
It was for future line, so it had a stub of pipe & end cap on it, valve closed
When the future work was being carried out, it was found valve would not hold, so pumped out & inspected, this was found.
Appears pressure so great it hydraulic forces destroyed valve.
Valve was put in with direction of flow from header to pipe stub.
Attachment 13957
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30-12-2015, 10:17 AM #2
Re: Damaged stop valve
Interesting, in hindsight maybe it should have been left open..
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30-12-2015, 12:03 PM #3
Re: Damaged stop valve
I wonder if some liquid got passed the valve when the system was off (or it condensed there) then when the system was back running again it warmed up, pressures went sky high as no expansion room and resulted in the damage seen.
I'm sure we have all seen split 1/4" caps on service valves where i think similar may have happened. (assuming they all aren't the result of overtightening by previous techs)Mostly found in Oxfordshire, UK :)
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30-12-2015, 08:23 PM #4
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30-12-2015, 08:27 PM #5
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30-12-2015, 11:00 PM #6
Re: Damaged stop valve
Hi Ranger1.
definitely interesting failure, a lot of energy to damage valve head like that. Assume it was closed against future flow, possible it was installed misaligned , bolted up hard and distorted head. Would have been interesting/ alarming cutting into stub with out a pump out, or did you have a service valve in stub.
magoo
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31-12-2015, 02:40 AM #7
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31-12-2015, 09:16 AM #8
Re: Damaged stop valve
Failure of many new valves Danfoss recently I saw, I think in your liquid. Such a valve must be designed for the liquid and on occasion, we see that it is not.
Can not believe a long-established products.
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31-12-2015, 09:34 AM #9
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31-12-2015, 09:57 AM #10
Re: Damaged stop valve
Either way-liquid or gas valve must survive.
I had this year many new valves fail, to look at unknown why, but the leak.
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31-12-2015, 07:16 PM #11
Re: Damaged stop valve
josef what type of failures?
Assume we are talking Danfoss
They have a few mistakes, especially since China it seems.
They had gland issues on some larger valves which seized due to threads on gland & valve being out.
Have also seen where they won't close properly in a few cases.
We were concerned & found ball bearings in valve shoe assembly had notches in bearing type race.
Valve shoe has a type of bearing race & somehow in their test procedure in factory they get damaged.
We found on one occasion valve shoe wanted to turn with valve spindle due to notches in bearing which prevented it closing tightly.
Also on some hand wheel prevented valve closing as it fouled with gland.
On inspection of a number of larger new valves that they are all damaged, but deemed OK by Danfoss.
There is not many things worse than not being able to trust a stop valve, especially if major pump outs are required to fix them.Last edited by RANGER1; 31-12-2015 at 07:19 PM.
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01-01-2016, 12:21 AM #12
Re: Damaged stop valve
One of the reason can be that this valve worked as check valve. Some gas leaked through and condensed inside the valve until it was full of liquid refrigerant. Later when outside conditions became warm liquid tried to expand but no room for that.
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01-01-2016, 01:48 AM #13
Re: Damaged stop valve
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03-01-2016, 09:53 PM #14
Re: Damaged stop valve
Hi Ranger
Thanks for posting this.
We are the same as you, we always shut the valves but after this we may have to rethink as well.
We have had issues with some of the larger Danfoss stop valves not shutting properly even though they have been pulled up fairly tight on the seat.
Maybe the quality has dropped.
Regards
PaulBorn to fish, forced to work
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03-01-2016, 11:42 PM #15
Re: Damaged stop valve
Paul,
As I mentioned in earlier post, maybe hand wheel in fouling on gland or faulty gland.
The faulty gland issue was about 12 to 18 months ago.
I can only encourage you to contact Danfoss about it as a problem.
We got them around on one job before stops were installed, no one want to do major pump ours & then find valve leaks when you want to tie it in to new equipment.
To my knowledge as well they are the only ones who make that tapered seat business, all older valves have flat seat which is better in my book.
Las per instructions also never mount with spindle down, as valve seizes, guaranteed.