Safety Valve Testing
AssigneeSeetru Limited
InventorOtto Herman Varga
Life of this patent
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Abstract
A method of measuring the condition of a safety valve comprises measuring a condition parameter that varies with the sealing force of the valve. The condition parameter may be determined from in-line measurements, such as measurements of a pressure pso at which the valve will open and a pressure psl at which the valve will leak.
Claims62
A method of measuring the condition of a safety valve, the method comprising measuring a condition parameter that varies with the sealing force of the valve.
A method according to any foregoing claim including determining a leaking parameter that varies with the pressure that will cause the valve to leak.
A method according to any foregoing claim including applying a lifting force to a closure member of the valve thereby to cause fluid to leak through the valve, and measuring a leak-producing lifting force at which the leaking occurs.
A method according to any foregoing claim including applying a lifting force to the closure member thereby to cause the valve to open, and measuring a valve-opening lifting force at which the valve opens.
A method according to any foregoing claim wherein a lifting force is applied to a rigid element connected to the closure member.
A method according any preceding claim, comprising the step of adjusting the valve to a desired pressure set-to-leak value psl.
A method according to any foregoing claim, wherein the sealing force f is equal to the difference between a valve opening force and a force required to counterbalance the corresponding inlet fluid force.
A method according to any foregoing claim wherein the condition parameter is the sealing force, or a pressure equivalent thereto.
A method according to any preceding claim wherein the condition parameter is based on the ratio of the sealing force f to a cold lifting force Fc, or a force related thereto.
A method according to any foregoing claim, wherein the condition parameter of the valve is calculated using the ratio:
- f
- (
- f
- +
- psl
- ·
- A
- )
- where psl is the pressure set-to-leak.
A method according to any foregoing claim, wherein the condition parameter of the valve is calculated using the ratio:
- 1
- (
- 1
- +
- psl
- f
- ·
- (
- Fh
-
-
- 1
- -
- Fh
-
-
- 2
- pr
-
-
- 2
- -
- pr
-
-
- 1
- )
- )
- where psl is the pressure set-to-leak.
A method according to any foregoing claim wherein the condition parameter of the valve is the ratio of the sealing force f to a cold lifting force Fc and is calculated using the ratio:
- f/Fc
A method according to any preceding claim, wherein at least one step of the method is carried out when the valve is installed in-line.
Apparatus for determining the sealing force of a safety valve comprising, a force sensor, a displacement sensor, a pressure sensor and means for applying a fluid pressure to a valve inlet.
Apparatus according to claim 38 or claim 39, further comprising an adjuster which, in use, compresses a valve spring to allow air pressure in the valve inlet to reach a predetermined pressure.
Apparatus for testing of a safety valve comprising force application means arranged to apply a lifting force to a closure member of a valve, and measuring means arranged to measure the lifting force that is sufficient to cause leaking of fluid through the valve, and the lifting force that is sufficient to cause opening of the valve.
Apparatus for testing a safety valve substantially as hereinbefore described with reference to any one or more of the accompanying drawings.
A method of testing a safety valve substantially as hereinbefore described with reference to any one or more of the accompanying drawings.
The use of the relationship between psl and pso as a measure of the state of quality of a safety valve.
Use of a relationship between psl and pso, the latter defined as the sum of a pressure at which the valve starts to leak psl and the pressure due to the sealing force f acting on an effective sealing area A, or from in-line determination of set pressure, for the measurement or characterisation of the state of quality of a safety valve.
A method of measuring the condition of a safety valve, the method including the step of measuring the pressure pso at which the valve opens.
Dependencies are inferred from the claim text.