@Nilsoni
Another thing you mention is "pressurized cavity". If the bore pressure and cavity pressure are equal there will be no "piston effect" on the seatring, and the valve will not seal.
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Does it mean that none valve with single piston effect will seal or just these mine from China...
After long working hours, endless testing, strong headaches, ... it is now my opinion that the problem is not the design - this design is known as "single piston" and it must be down to material quality and its strength to resist deformations when high pressure applies.
I am not sure if...
Yes, I am in contact with them.
They have no explanation. I asked them to come and see what is going on but still they are hesitating about it. I also send them a video of out testing, but they answered that testing method is not good - which I agree it should be better, but we can not test...
We have gauge connected to cavity and the nitrogen connected to other side and in to the same cavity.
Valve is working like safety valve - once pressure rise to certain level, pressure opens against the spring.
This is bad behavior in my view, bat that scenario will never happen in exploration...
In original there were 12 springs.
We added 12 more but those 12 are actually spring in spring so total of 36 springs.
The result is that the valve that was holding 15 and 50 bars from different places are now holding 20 and 60 bars.
It is step forward but very small. Beside that valve was...
@tr1ntx
We always first test seat just with pressure from one side in ball closed position and without pressure in valve cavity and on air 6 bar and water 250 bar, seats are tight - no leak.
The problem starts once pressure enters valve cavity.
As ball is in one piece with stem we measured...
Temperature is up to 40 deg C. Valves are metal seated due to very polluted gas as it is for underground storage facility and for high pressure - 275 bar operated pressure.
We tested with nitrogen from bottle, so pollution is not the case for our our testing.
We now tried the other same size/rate valve.
From one side it leaked on 15 bar. We than tried on 10 it was good. Again on 15 and it leaks.
After that we tried on the other side same valve, and it was good on 10, 20, 30, 40,50 bar and on 65 it leaked. Than tried again on 50 and it was good...
Valves were only tested with water. During startup with natural gas, problem is started. Actualy, once high pressure fluid enters valve cavity, problem starts. If the pressure is 50 bar, valve is working ok. If the pressure is 100 bar seats are like stuck and closed valve is leaking very much...
Actually we tried to drain cavity in closed position - I will try today in opened.
What is a bit frustrated is that our engineer was in China for witness testing, after that when valves arrived we tested at our facility, than valves were delivered to site and tested before the installation...
When you tried Step 5, was the 4" valve open or closed? - It was closed...
Yes we tried to open it fully, but it was leaking so much.
Manufacturer is from China with API6D certificate.
What we tried in test lab is to leave 1/2" drain valve opened all time and the pressure was applied from the...
I have experienced following problems with 4" #1500 ball valves - metal seated, top entry, double-block-and-bleed.
4" #1500 Ball valve is with seats that are pushed by springs against the ball. In the middle of ball valve, there is 1/2" hole drilled to ball cavity in which we connected drain...
