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RANGER1
30-12-2015, 07:28 AM
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.
13957

HVACRsaurus
30-12-2015, 10:17 AM
Interesting, in hindsight maybe it should have been left open..

monkey spanners
30-12-2015, 12:03 PM
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)

RANGER1
30-12-2015, 08:23 PM
Interesting, in hindsight maybe it should have been left open..

That's what we are thinking, but of course have always closed in the past.
If it was a liquid line stub for future connection, normally would close, but now not sure.

RANGER1
30-12-2015, 08:27 PM
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)

Will find out orientation of stub, as you would think it would have to be a vertical stub pointing downwards.
The pressure must have been very high to cause this.

Magoo
30-12-2015, 11:00 PM
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

RANGER1
31-12-2015, 02:40 AM
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

Let's just say we normally install a socket & screw in a valve to relieve any possible pressure etc.

josef
31-12-2015, 09:16 AM
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.

RANGER1
31-12-2015, 09:34 AM
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.

josef,
It appears liquid has had hydraulic effect, but not sure why.
If valve seat did not fail, I guess pipe failure next, maybe we were lucky.

josef
31-12-2015, 09:57 AM
Either way-liquid or gas valve must survive.
I had this year many new valves fail, to look at unknown why, but the leak.

RANGER1
31-12-2015, 07:16 PM
Either way-liquid or gas valve must survive.
I had this year many new valves fail, to look at unknown why, but the leak.

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.

Segei
01-01-2016, 12:21 AM
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.

RANGER1
01-01-2016, 01:48 AM
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.

Segei, we figure that's what happened, but has been done countless times over the years.
Maybe have to leave open in future!
It was a new valve, never used , so aware that they have to be re-tightened a few times, which is another pain from Danfoss valves.

PaulZ
03-01-2016, 09:53 PM
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
Paul

RANGER1
03-01-2016, 11:42 PM
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
Paul

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.