GB2139737A - Valve testing system - Google Patents

Abstract

In an hydraulic power system (50, Fig. 1) for using in a valve testing apparatus comprising an hydraulic fluid reservoir 52 and an hydraulic pump 54 operative from time to time to charge a large capacity hydraulic accummulator 56 capable of storing hydraulic fluid for several valve testing operations, a pressure regulator 74 is operative to deliver hydraulic fluid for valve testing operations. Actual operation is controlled by fluid flow control means, for example a fluid routing valve 80 of a sliding spool type. Charging of the accummulator 56 may be monitored by a pressure gauge 68, and a pressure gauge 84 may monitor applied operating pressure to enable adjustment of regulator 74. <IMAGE>

Description

SPECIFICATION Valve testing system The invention relates to apparatus for making checks on the functioning of valves, particularly safety or reliefvalves, of pressurised systems our vessels without the necessity eitherto close down an operating such system our vessel orto generate overpressures therein.

A successful apparatus operates on the basis of applying, via coupling means, force to actuators of valves being tested in order to open same, and measuring stress/strain in a connection between that coupling means and a frame associated, or more usually temporarily associatable, with each valve and/or adjacent parts of a system orvessel. It is convenientto apply such force hydraulically and then measurethatforcebyastrain gauageordynamo- meter in or of said connection, rather than to measure hydraulic pressure and seekto relate thatto actual force andlare equivalent pressure atthe valve itself. In addition, it is useful to measure valve closure or reseating force and also to provide for powered valve closure or reseating.Preferred hydraulic drive systems include an accumulator in orderto smooth out pump pulsations that could otherwise affect the system as a whole and to set the applied hydraulic pressure, which involves dumping hydraulicfluid backto reservoir as necessary.

Our main application for such valve testing apparatus is as readily portable apparatus taken to around the plant, effectively from valve to valve, and we now seek particularly to provide advantageous such equipment.

According to one aspect ofthe present invention, there is provided valve testing apparatus having valve forcing means physically to operate the valve using an hydraulic power system of the apparatus and stress strain measuring means operative relative to a connection mechanically applying forceto valve actuator coupling, wherein the hydraulic powersystem comprises an hydraulic fluid reservoir, a pump operativefromtimetotimeto charge accumulator means capable of storing hydraulic fluid for several valve testing operations, pressure regulator means operative to deliver hydraulic fluid forvalve testing operations, and fluid flow control means between the accumulator means and the pressure regulator means.

Provision is preferred for a charge state indicator, say a pressuregauge, forthe accumulator means.

Pump operation can then be in relation to a maximum or desired pressureforthe accumulator means and a quantity of fluid that is large comparedwith normal valve test operation cycles. Thereafter, the apparatus will testvalves until the accumulator pressure drops below the delivery rating of the pressure regulator, which will occur as accumulator contents are used up in successive valve test operations. Compared to the above mentioned "smoothing" accumulator system, the accumulator means hereof is of large capacityand does not set actual applied operating pressure, and there is much more efficient use of pressurised fluid as such is not dumped to reservoir in order to set and maintain operating pressure, returns to reservoir being limited to fluid actually used in the test cycle.

A particularly convenient hydraulic pump is of the compressed-air-operated type resulting in a very compact hydraulic power system requiring only periodic coupling to a compressed-airsupply, also itself readilytaken from a site to site and about particular sites.

It is advantageous to measure actual applied operating pressure as late as possible, specifically at output from the hydraulic power system, and to adjust the pressure regulator accordingly, thereby avoiding any adverse effects from pressure loss/absorption in desired outputting means including a routing valve, preferably also variable restriction means as flow regulators.

Given the overall desiderata in relation to readily portable, easily used apparatus, another aspect ofthis invention concerns the routing valve, which we propose shall be of a three-position type, one for pressurised fluid flow to operate thevalve undertest, one forpressurised fluid flow focibly to reseat the valve undertest, and an intermediate position for unpressurised fluid return to reservoir as the valve undertest reseats itself automatically. It is preferred that such a valve, which may be conveniently of sliding spool type, be hand-lever operated.

Practical implementation ofthis invention will now be described, by way of example with reference to the accompanying drawing, in which: Figure lisa part-diagrammatic representation of valve testing apparatus; and Figure 2 is an hydraulic circuit diagram of the hydraulic powersystem of Figure 1.

In the drawings, a valve 10 to be tested is shown with pressure lines 12, 14 into and out of it, and has an actuator in the form of a valve spindle 16 to which access is gainedfortesting hereof, usually simply by removing a valve cover.

A rigid mechanical frame 20 is shown seating at 22 on the valve body realtive to which it may be suitably secured. There is access to the valve spindle 16 through the frame 20 for a coupling piece 24 shown as a top-hat shape usually screwing or otherwise gripping the end of the spindle 16. The coupling piece 24 is itself held firmly via a chuck or adaptor 26 rigid directly or indirectly with a load cell 28 that is acted upon by an hydraulic ram 30 that is fixed relative to the frame 20, say at an upper tolerance/flexibility in the connection ofthe chuck 26 and the coupling piece 24where the frame 20 cannot accurately be centralised overthe spindle 16. Suitable provision in this respect is via a loose pin connection, see 25.

The hydraulic opening and closing rams 30 and 32 have fluid input ports 34, 36to each side of its piston 38, and hydraulic lines 40,42 therefrom to easyrelease couplings 44, 46 for connection to an hydraulic power pack 50, usually via long hoses in orderto keep the hydraulicsandthe operatorwell awayfrom heat, steam discharge, dust, etc encountered at valve lift. It will, of course, be appreciated that a double acting hydraulic ram could be used instead ofthetwo series rams 30 and 32, though the latter is much simpler in operation.

Details ofthe hydraulic power pack 50 are shown in Figure 2 as including an hydraulicfluidreservoir52,an hydraulic pump 54, and a large capacity hydraulic accummulator 56. The preferred illustrated pump 54 is operated by compressed-air, see air coupler 58 and air filter 60 in air line 62to the pump, and serves to draw fluid via line 64from the reservoir 52 and deliver it pressurised over line 66 to the accummulator 56.

Charging ofthe accummulator 56 by the pump 54 is readily monitored via a pressure gauge 68 and will be to a pressure and in a quantity offluid sufficientto perform several valve tests without recharge, typically at least.

The apparatus hereof is rendered ready for operation by way of an on/offvalve 70 in output 72 of the accummulatorthatsupplies a pressure regulator 74 when the valve 70 is opened.

Actual operation is controlled by a fluid routing valve, shown as if the sliding spool type, and receiving fluid from the pressure regulator 74 over line 76 with a return to the reservoir 52 over line 78. The routing valve state shown is for return to reservoir of unpressurised hydraulicfluid should that be required by movement of the cylinder piston 38, say on automatic reseating by the valve under test. That state is intermediate to state representing pressurisation of line 42 and connection of line 40 to reservoir (left hand) and vice versa (right hand), corresponding to forced opening of thevalve undertest and forced reseating thereof, respectively. The routing valve 80 is prefer ably levered operated, see 82 in Figure 1.

A pressure gauge 84 is shown forthe line 42 to monitor actual applied operating pressure, and enable suitable adjustment of the pressure regulator 74. In practice, for our preferred power pack, connection of the gauge 84will normally be on the routing valve side of easy-release coupling 44,46.

Also shown in Figure 2 are variable constriction valves 86,88 in lines 76,78 forflow-rate setting purposes. Such valves 86,88 may be ofthewell known needle-type.

Lastly, we advert two the pressure sensor 90 in line 12 tothevalve 10 useful in preferred use of recording apparatus, typically ofthree-pin type, with inputs from the valve 90,the load cell 28 and a movement transducer.

Claims (10)

1. Avalvetesting apparatus havingvalveforcing means physicallyto operate the valve using an hydraulic power system of the apparatus and stress/ strain measuring means operative relative to a connection mechanically applying force to a valve actuator coupling, wherein the hydraulic power sys- tem comprises an hydraulic fluid reservoir, a pump operativefromtimetotimeto charge accummulator means capable of storing hydraulicfluidforseveral valve testing operations, pressure regulator means operative to deliver hydraulic fluid for valve testing operations, and fluid flow control means between the accummulator means and the pressure regulator means.

2. An apparatus as claimed in claim 1, including a routing valve of a three-position type, one for pressurised fluid flow to operate the valve undertest, onefor pressurised fluid forciblyto reseat the valve under test, and an intermediate position for unpressurised fluid return to reservoir as the valve undertest reseats itself automatically.

3. An apparatus as claimed in claim 2, operable by a hand-lever.

4. An apparatus as claimed in claim 2 or 3 of sliding spool type.

5. An apparatus as claimed in any one of claims 1 to 4, wherein the accummulator means has a charge state indicator.

6. An apparatus as claimed in claim 5, wherein the charge state indicator is a pressure gauge.

7. An appartus as claimed in any one of claims 1 to 6, wherein the hydraulic pump is a compressed-airoperated type.

8. An apparatus as claimed in any one of the preceding claims, further comprising outputting means including a routing valve.

9. An apparatus as claimed in claim 8 further comprising variable restriction means asflow regulators.

10. An apparatus substantially as hereinbefore described with reference to and as illustrated in the accompnying drawings.