GB2519771A - Pressure relief valve - Google Patents

Pressure relief valve Download PDF

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Publication number
GB2519771A
GB2519771A GB1319097.0A GB201319097A GB2519771A GB 2519771 A GB2519771 A GB 2519771A GB 201319097 A GB201319097 A GB 201319097A GB 2519771 A GB2519771 A GB 2519771A
Authority
GB
United Kingdom
Prior art keywords
valve
pressure relief
closure member
pressure
relief valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1319097.0A
Other versions
GB201319097D0 (en
Inventor
David Bailey
Ian Wilson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fort Valve Engineering Ltd
Original Assignee
Fort Valve Engineering Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fort Valve Engineering Ltd filed Critical Fort Valve Engineering Ltd
Priority to GB1319097.0A priority Critical patent/GB2519771A/en
Publication of GB201319097D0 publication Critical patent/GB201319097D0/en
Publication of GB2519771A publication Critical patent/GB2519771A/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/36—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position
    • F16K17/38—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position of excessive temperature
    • F16K17/383—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position of excessive temperature the valve comprising fusible, softening or meltable elements, e.g. used as link, blocking element, seal, closure plug
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D51/00—Closures not otherwise provided for
    • B65D51/16—Closures not otherwise provided for with means for venting air or gas
    • B65D51/1633—Closures not otherwise provided for with means for venting air or gas whereby venting occurs by automatic opening of the closure, container or other element
    • B65D51/1644—Closures not otherwise provided for with means for venting air or gas whereby venting occurs by automatic opening of the closure, container or other element the element being a valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K1/00—Lift valves or globe valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces
    • F16K1/32—Details
    • F16K1/34—Cutting-off parts, e.g. valve members, seats
    • F16K1/44—Details of seats or valve members of double-seat valves
    • F16K1/443—Details of seats or valve members of double-seat valves the seats being in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
    • F16K17/0413—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded in the form of closure plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
    • F16K17/044—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with more than one spring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/04—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded
    • F16K17/0466—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side spring-loaded with a special seating surface
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/02—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side
    • F16K17/14—Safety valves; Equalising valves, e.g. pressure relief valves opening on surplus pressure on one side; closing on insufficient pressure on one side with fracturing member

Abstract

A pressure relief valve comprises a valve body having an inlet, a first valve closure member 38, means 42, 44 for biasing the first valve closure member 38 toward engagement with a first valve seat 35, and a second valve closure member 40 engagable with a second valve seat 36 and responsive to pressure at the valve inlet. A retaining member 74 retains the second valve closure member 40 in engagernent with the second valve seat 36, in which position the first valve closure member 38 is isolated from the valve inlet. The retaining member 74 is configured to rupture at a predetermined pressure on the second valve closure member 40, allowing it to move out of engagement with the second valve seat 36 and permitting communication of the first valve closure member 38 with the inlet.

Description

PRESSURE RELIEF VALVE
The present invention relates to pressure relief: valves.
Pressure rehef valves are fitted to vessels carrying gases and liquids in order to aVow venting of the contents in extreme circumstances such as an increased pressure due to fire engulfment, in order to prevent explosion of the vesseL The pressure rehef valve is fitted to a port located in the waV of the fluid vessel and typicafly comprises a valve closure member which is biased toward engagement with an annular valve seat by means of very strong or muFtiple compression springs within the housing of the valve. in the event that the pressure within the vessel to which the valve is tilled increases to a level which would otherwise cause a catastrophic increase in pressure within the vessel, the pressure on the valve closure member lifts it off the annular valve seat, against the restonng forces of the spring or springs, and aVows the pressurised contents in the fluid vessel to be vented in order to reduce the pressure within the fluid vesasi, in some circumstances. springbiased pressure relief valve are unsuitable for use. For example, when the pressure reHef valve is used on a rail tank, a high set pressure is required when the tank is transporting cargo, in order to prevent surging ci the liquid within the tank from opening the valve against th.e restoring forces of the spring or springs, in such circumstances, the valve closure member can be held in piece by means of a shear pin or buckle pin, instead of using springs, which can he set to a higher pressure relief value which will still provide pressure relief in a potentially catastrophic situation but which wifi not open during transport as a result of surging of liquid within the tank.
One of the probems with such vSves, however. is that once the shear pin or bucke pin has ruptured, the vave no anger provides a pressure reef tunoton since it is etfectivSy open.
II woud be de&rab!e to have a pressure rehef vave wftch is resistant to opening as a resuh of Uquid surge but which stifl provides a pressure reHef function, at a ower pressure ev&, after the vave has first opened.
hi accordance with the present invention, a pressure reUef vaive comprises a vave body having an met, a first vave seat. a first vave c'osure member r&easabiy engagable wfth the first vave seat. biasing means for biasing the first vaive dosure member toward engagement with the first vaive seat, a second vave closure, member releasahiy engagable with a second valve seat and responsive to pressure at the valve inlet and a retainftig member which retains the second vave closure member in engagement with the second valve seat, in which position the first valve closure member is isolated from the valve inlet, the retaining member being configured to rupture upon application of a predetermined pressure to the second valve closure member, thereby aflowing the second valve closure member to move out of engagement with the second valve seat and permitting communication of the first valve closure member with the inlet, hi this specIfication, the term rupture" is intended to include any action in which a nonresientlv deformab.ie change is made, such as shearing, buckling, plastic deformation, jc.
With the present invention, the retainhig member can be set to rupture at a higher pressure value than the biasing means, thereby preventing inadvertent opening of the valve due to Uquid surge during transport Once the pressure relief valve has opened for the first time, as a result of excessive pressure within the vessel to which the valve is attached. the retaining member wW be ruptured. Mowing the valve to open. However, the valve wiN still provide a pressure reflef funcfion as a result of the biasing means acting on th.e first valve closure member. This can be important in circumstances when the vessel to which the valve is connected is in a fire engutfment situation, in which the valve set pressure needs to drop to a lower pressure, preventing the tank from exploding until most of the cargo has been ejected. The fire which causes the increase in pressure within the vessel may not always act on the pressure reNd valve direcuy, and consequently sNowing the valve to reset after its first opening provides an additional safety feature Preferably, the pressure rehef valve further comprises an elongate member extending from the second valve closure member, preferably from the rear face of the second valve closure member.
The pressure reNal valve may further comprise a first guide through which the elongate member extends, the retaining member engaging the first guide and the elongate member to prevent relative dispftwement. In a preferred embodiment, the retaining member extends through aligned apertures in the elongate member and the first guide.
Preferably, the elongate membe.r passes sealingly through the first guide. in one embodiment, the guide is tubular.
In one embodiment, the retaining member is configured to shear on application of a predetermined pressure to the second valve closure member.
The retaining member may comprise a pin.
The pressure reflef valve may further comprIse a second guide means through which the first guide means extends, and one or more fusible retainer means which prevent relative movement of the first and second guide means below a it) predetermined temperature. The fusible retainer means may comprise a fusible plug.
In another embodiment, the elongate member forms the retaining member.
The retaining member may be configured to deform non-resiliently on application of a predetermined pressure to the second valve closure member. For example.
the retaining member may comprise a bucide pin.
The end of the elongate member remote from the second valve closure member may be secured to a mounting which is received in a guide means fixed with respect to the valve body. The guide means may be tubular.
The valve closure member may further comprise one or more fusible retainer means which prevent relaflve movement of the elongate member and the guide means below a predetermined temperature. The fusible retainer means may comprise a fusible plug.
By way of example only. specific embodiments of the present invention will now he described with reference to the accompanying drawings, in which: Fig. I a a side view of a first embodiment of pressure rehef valve in accordance with the present invention; Fig. 2 is a plan view of the pressure reUef valve of Fig 2; Fig. 3 is vertical cross section through the pressure relief valve of Fig. 1, coking in the direction of arrows Ct: Fig. 4 is a vertical cross section of the pressure relief valve of Fig 1, coking in the dimction of arrows Ct. in a condition where a shear pin has sheared: Fig. 5 is a verticai cross section of the pressure relief valve of Hg. I, looking P. the direction of arrows Ct, in a fully open cond!ton: Fia. $ is a vertical cross section through. the pressure relief valve of Fig. 1, ookr.g in the direction of arrows Ct. in a condition, where a fusible plug has been actuated: Fig. 7 is a side view of a second embodiment of pressure reflef valve in accordance with the present invention: Fig. $ is a pian view of the pressure relief vah,e of Fig. 2; Fig. 9 is vertical cross section throuoh the pressure relief valve of Fig. 7, looking n the. direction of anows CC; Fig. 10 is a verLical cross section of the pressure rehef valve of Fig. 7. iookinq in the direction of arrows CC, in a condition where a buckle pin has buckled; Fig. ii is a verfical cross section of the pressure relief valve of Fig. 7, looking in the direction of arrows C-C, in a condition where a fusible plug has been actuated; and Fig. 12 is a vertical cross section through the pressure relief valve of Fig. 7, looking in the direction of arrows CC. in a condition where a fusible plug has been actuated and the valve is in the fuUy open condition.
Referring firstly to Figs. I to 6, a pressure reflef valve 10 comprises a valve body having an annular securing flange 12 having planar upper and lower faces 14, 16 and 8 equafly angulady spaced apertures 1' for securing the valve to a valve mounting pad (not shown) on a vessel tank. The valve body further comprises a generally cylindrical side wall 18 welded or cast to the upper face of the securing flange 12. The side wail 18 is provided with four identical equay anguiary spaced curved rectangular windows 20 adjacent to the upper face 14 of the securing flange 12, defining four identical supporting legs 22. A cap 24 having a cylindrical wall 26 extending from the periphery of a circidar end wail 28 is removably and screw4hreadedly connected to the upper end of the cylindrical sae wail 18 of the valve by means of inter engaging screw threads 30 on the exterior Face of the upper portion of the cyhndricai side wail 18 of the valve body and on the interior face of the end portion of the cynddcal waD of the cap 24. A tamper-evident seal 32 s secured between the cap 24 and the cy ndricai side waD 18 of the valve body.
As boat seen in Fig. 3, radiay inwardly of the cyndrical side waD 18, the securing flange is formed into a valve passage having a frustoconical portion 34 which is contiguous with a cykndricai or tubular portion 35 which opens into the interior of the vave body. Radially outwardiy of the cyndrice passage 35, the upper face 14 of the securing flange 12 is formed into a generafly planar annular vve seat 35.
A first valve closure member 38, in the form of a circular metal disc, is slidably and seanoly dsonsed in he cyiinddcal portion iS of the valve pnssane A second circular disclike valve closure member 40 is releasably engagable with the generaDy planar annular valve seat 36 and is strongly biased towards engagement with the valve seat 36 by means of two strong coaxial compression springs 42: 48 extending between the inner face of the end wail 28 of the cap and the upper face of the second valve dosure member 40. The first valve closure member 38 is also slidably and sealingly seated in a complernentarily-shaped recess 45 in the undersurface of the second valve closure member 40.
As best seen in Fiq. 3, the second valve closure member 40 comprises first and second valve closure portions 46, 48 which are releasably securabie to one another by means of a olurality of countersunk bolts 50 to form the valve closure member 40, The;rst valve closure portion 46 is in a form of circular disc whc'se CareLer is very slightiv smaller than the inner diameter of the cylindrical side waD I 8 so that the valve: closure member 38 may be displaced out of engagement / with the valve seat 36 against the restorinq force of the sprIngs 42, 44. The springs 42, 44 engage the face of the first valve closure portion 46 and the outermost sprina 42 engages the upper face of each of the countersunk bolts 50, thereby preventing the bolts from being oosened, for example by vibration. g
The second valve closure portion 48 sits in a recess 52 in the lower face of the first valve closure portIon 46 opposite to that engaged by the springs 42, 44.
When the first and second valve closure portions $6, $8 are ssernbied to form the valve dosure member 40. they define an annular seal groove $0 at the peripherj of the recess 52, for receipt of a complementadly shaped deformable Oring seal 62. Other than for the groove $0 the second valve closure portion $8 is shaped oompiementariiy to the recess 52 in the first closure portion and nests seaHngiy within the recess 52.
As best seen in Fig. 3. the first valve closure member 38 is mounted on an elongated oyhndrical guide rod 64 which extends to the upper surface of the end cap 2$. The guide rod 64 passes sealingly through an appertured boss $6 in the centre of the second valve closure member 40. An annular collar 68 secured to the rod 64 limits the downward displacement of' the first valve closure member 36 with respect to the second valve closure member $0. twill lso be observed that any upward movement of the first valve closure member 38 with respect to the second valve closure member 40 results in receipt of the first valve closure member $8 further into the recess 45 until it abuts the end face of the recess 45.
The upper end of the guide rod 36 is slidably and sealingly received ri an inner.
tubular guide member 72. As seen in Fig, 3, a shear pin 7$ passes diametricay through the guide rod 84 and aligned recesses In diametrically opposed portions of the guide tube 72.
The inner guide tube 72 is Itself sHdably and sealingly mounted in a further, outer guide tube 73 which is secured to the cap 24. A circumferential groove 76 Is formed in the outer surface of the Inner guide tube 72 towards Its lower end and a plurality of fusible plugs 78 (only one of which is visible) each retains a ball bearing 80 within the groove 76, thereby preventing movement of the Inner and outer guide tubes 72, 73 wtth respect to one another, except in the event of excessive temperatures, as will be explained.
In use, the pressure relief valve whO normally assume the cond Won illustrated in Figs. I to 3. In this condition, the first valve closure member 38 is retained in position In the cylindrical portion 35 of the valve passage by means of the shear pin 74 passIng through the guide rod 64 and the guide tube 72. In this condition, the second valve closure member 40 Is also held in sealing engagement with the planar valve seat 36 by means of the springs 42. 44. In this condition, the pressure relief valve is set to a high pressure which is suitable, for example, when the tank to which the valve is fitted is transporting a liquid cargo, in which a surge of liquid during transportation might otherwise cause the valve to open If it were held shut only by means of springs.
In the event of a fire engulfment situation, where the pressure in the vessel to which the valve Is fitted Increases catastrophically, the pressure on the first valve closure member 38 will ultimately cause the shear pIn 74 to shear. This causes the first valve closure member 38 to move upwardly further into the recess 45 in the undersurface of the second valve closure member 40, as shown in FIg. 4. It
G
wHI also be observed that in this condition, the upper end of the guide rod 64 projects out of the end cap 24, providing a visual indication that the shear pin has sheared. The pressure then farces bath he ñrst and second valve closure members 38. 40 furher upwardly, against the restoring force of the compression springs 42, 44, as shown in Fig. 5. In this condition, the opening and closing of the valve is controfled by the compression springs 42, 44, as the severed shear pin 74 no longer has any effect on the dosing of the valve.
This arrangement ensures that, once the pressure on the valve has exceeded the value necessary to shear the shear pin, the valve set pressure then drops to a lower pressure set by the springs 42, 44, preventing the tank to which the valve is fitted from exploding und most of the cargo has been ejected. The valve can also then reset and operate at a lower pressure.
With reference to Fig. 6, in the event that the valve itseif is in a fire engulfment situation, to the extent that its temperature increases excessive!y, the fusible plugs 78 will melt, allowing the ball bearings 80 to leave the drcumferenti groove 76 and thereby permitting the inner guide tube 72 to slide within the outer gwde tube 73. irrespective of whether the shear pin 74 has sheared, in such circumstances, and as shown in Fig. 6, if the force on the valve closure members 38ç 40 exceeds the restoring forces of the springs 42, 44, as may well happen if the temperature increases, the first valve closure member 38 will move fbrther into in the recess 45 in the undersurface of th.e second valve closure member 40 and the valve set pressure will be determined by the springs 42, 44. in this situation, botn the guide rod $4 and the inner guide tube 72 project from the upper end of the cap 24, providing a visual indication that the fusible plugs have melted. in
A second embodment of the present nventk,n a mustrated in Figs. 7 to I 2 A number of the components of the second embodiment are identicaL or very similar, to corresponding components of th.e first embodiment and in the following $ description such components of the second embodiment are idenUfied by the same reference numerals as in the first embodiment, with the addition of a dash..
The second embodiment of pressure rekef valve IC' comprises a valve body having an annuar securing flange 12' havina planar upper and lower faces 14, 16' and 8 equally angularly spaced apertures 17' for securing the valve to a valve mounting pad (not shown) on a vessel tank. The valve body further comprises a generally cy ndrical side wall 1$ walded or cast to the upper face of the securing flanac 12. The &de wall 18' is provded wfth four identical equally anguiarly spaced curved rectangular windows 20' adjacent to the upper face 14' of the securing flange 12, defining four identical suppordng legs 22. A cap 24' having a cyllndrical waD 26 extending from the periphery of a circular end wall 28' is removably and screw4hreadedly connected to the upper end of the cylindrical side wall 18' of the valve by means of inter engaging screw threads 30' on the extenor face of the upper portion of the cyllndrical de wall 18' of the valve body and on the interior face of the end porfion of the cyllndricai wall of the cap 2$'. A tampeNevident seal 32' is secured between. the cap 24' and the cyllndrical side wall 18' of the v&ve body.
As best seen in Fig. 9, radially inwardly of the cyllndrical sidewall 18', the securing flange is formed into a valve passage having a frustoconical portion 3-4' which is contiguous with a cyhndricai or tubular portion 36' which op-ens into the ntenor of the vave body. Raaaiiy outwardly of the cyndncal passage 3', the upper face 14 of the securing flange 12 is formed mto a generay planar annuiar valve seat 3ff.
A first valve cosure member 38, in the form of a circular metal disc, is shdably and seangiy disposed in the cylindrical portion 35' of the valve passage. A second circular discDke valve closure member 40 is releasably engagable with the generaUy planar annular valve seat 36 and is strongly biased towards engagement with the valve sect 36 by means of two strong coaxial compression springs 42', 44' extending between the inner face of the end wa 28 of the cap and the upper face of the second vave closure member 40'. The first vaM closure member 35' is also slidably and seahngly seated in a complementarily shaped recess 45' in the underswface of the second valve closure member 40'.
As best seen in Fig.. 9. the second valve closure member 40 comprises first and second valve closure portions 46'. 48' which are releasably securabe to one another by means of a plurality of countersunk bolts 50 to forn the valve closure member 40'. The first valve closure portion 46 is in a form of circular disc whose diameter is very sgh.ty smaller than the inner diameter of the cylindrical side wafl so that the valve closure member 38' may be displaced out of engagement with the valve seat 36' against the restoring force of the springs 42', 44'. The springs 42', 44' engage the lace of the first valve closure portion 46 and the outermost sphng 42 engages the upper face of each of the countersunk bolts 50', thereby preventing the bolts from being loosened, for example by vibration.
The second valve closure portion 48 sits in a recess 52' in the lower face of the first valve closure portion 46' opposite to that engaged by the springs 42', 44'.
When the first and second valve closure portions 46', 48' are assembled to form the valve closure member $0', they define an annular seal groove 60' at the periphery of the recess 52', for receipt of a complementarily shaped deformabie Oring seal $2'. Other than for the groove $0, the second valve closure portion 48' is shaped complemeniarily to the recess 52 in the first closure portion and nests seailngly within the recess 52.
As best seen in Hg. 9, one end of an elongate buckle pin 90 is seated (but not secured) in a recess 91 in the upper end of a lower mounting boss 92 attached to the upper face of the first valve closure member 38', the boss 92 passing seahngly and shdabiy through an aperture 69 extenthng through the centre of the second valve closure member 40.' 4. coar 6$ is secured to the upper end of the mounting boss 92 to limit the downward dIsplacement of the first valve closure member 36' with respect to the second valve closure member 40'. It wifi also he observed that any upward movement of the first valve closure member 38' with respect to the second valve closure member 40' results in receipt of the first valve closure member 38' further into the recess 45' until it abuts the end face of the recess 45'. An annular wire clip 93 is also seated in a circumferential groove in the outer face of the lower mounting boss 92, in contact with the peripheral wail of the aperture 89 extending through the centre of the second valve. ciosure member 40'. The clip serves o secure together the first and secon.d valve closure members 38', 40' when the first valve closure member 38' is fully seated in the recess 45', as will be explained.
The buckle pin 90 is configured to buckle in a nonreversible manner when the compressive forces applied to its opposite ends exceeds a predetermined value, -4.-The opposite, upper end of the buckle pin 90 is secured to an upper cylindricS mounting block 94, which in turn is afidably and seangly mounted in a circular guide tube 96 secured to the centre of the cap 24. A orcumferenual groove 98 is formed in the outer surface of the cylindrical mounting block 94 towards its upper end and a pluraty of fusibe plugs 100 (only one of which is visible) each retains a ba hearing 102 in the groove 98. thereby preventing movement of the buckle pin mounfing block 94 with respect to the guide tube 96, except in the event of excessive temperatures, as will be explained.
In use, the pressure relief valve wUl normay assume the condition illustrated in Figs. 7 to 9. In this condition, the first valve dosure member 38 is retained in position in the cylindrical portion 35' of the valve passage. by means of the buckle pin 90 which extends between the end cap 24 and the mounting boss 92 attached to the first valve closure member 38 In th condition, the second valve closure member 40 is also held in sealing engagement with the planar valve seat 36 by means of the sprIngs 42', 44'. in this condition, the pressure relief valve is set to a high pressure which is suitable, for example, when the tank to which the valve is fitted is transporflng a liquid cargo, in which a surge of liquid during transportation might otherwise cause the valve to open it it were held shut only by means of springs.
In the event of a fire engulfment situation, where the pressure in the vessel to which the valve is filled increases catastrophically, the pressure on the first valve closure member 38 will ultimately cause the buckle pin 90 to buckle in a non reversible manner, as shown in Fig. 10. This causes the first valve closure member 36' to move upwardly further into the recess 45' in the undersurface of the second valve closure member 40', as shown in Fig. 10. The pressure then forces both the first and second vaive closure members 38, 40' further upwardly, against the restoring force of the compression springs 42. 44, as shown n Fig. 10. in this condition, the opening and closing of the vve is controed by the ccmpresson spnngs 42', 44', as the bucklea bucKle pn 90 no longer has any effect on the closing of the valve.
n this condition, the first valve closure member 38' is fuily received in the recess 45' in the undersurface of the second valve dosure member 40', in contact with the base wa of the recess 45. When the first valve dosure member $8' is fuy received in the recess 45', the lower mounting boss 92 has passed through the aperture 89 in the second valve closure member 40 to such an extent that the annular cp 93 carried by the boss 92 is no longer constrained within 89, whereupon it expands sghtly radiay outwardly (while stifi being seated in its circumferential groove in the outer surface of the boss 92) and engages the upper face of the second valve closure member 40' around the periphery of the aperture 89. This prevents the lower mounting boss 92 from passing back through the aperture 89 and thereby secures the first and second valve closure members 38. 40 together.
This arrangement ensures that, once the pressure on the valve has exceeded the value necessary to buckle the buckle pin 90, the valve set pressure then drops to a lower pressure set by the springs 42', 44'. preventing the vessel to which the valve is tilted from exploding until most of the cargo has been ejected The buckle pin 90 is retafted in the upper cyHndrica mounting block 96 and is only seated (but not secured) in the recess 91 in the lower mounting boss 92 and so as the valve doses, the ower end of the buckle pin becomes dislodged from the recess 91 in which it is seated. The vaive can also then reset and operate at a lower pressure.
With reference to Fig. 11 ana Fig. 12, in the event that the valve itseft is in a fire engul1hent situation, to the extent that its temperature increases excessively, the tusbie plugs 100 will mek. permitting the ba hearings 102 to cave the circumferential groove 96 and thereby aUowing the buckle pin mounting block 94 to &ide with respect to the guide tube 96, irrespective of whether the buckle pin has buckled. n such circumstances, and as shown in Figs. 11 and 12, If the force on the valve closure members 36', 40' exceeds th.e restoring forces of the springs 42', 44', as may well happen if the temperature increases, the first valve closure member 38' will move further into in the recess 45' in the undersurface of the second vaive ciosre member 40' and the valve set ressure will be determined by the springs 42, 44'. n this situation, the upper end of the buckle pin mounting block 94 proects from the upper end of the cap 24', providing a visual indication that the fusible pugs have melted.
The invention is not restricted to the details of the foregoing embodiments. 1$

Claims (19)

  1. CLAIMS1. A pressure relief valve comprising a valve body having an inlet, a first valve seat, a first valve closure member releasably engagable with the first valve seat, biasing means for biasing the first valve closure member toward engagement with the first valve seat, a second valve closure member releasably engagable with a second valve seat and responsive to pressure at the valve inlet and a retaining member which retains the second valve closure member in engagement with the second valve seat, in which position the first valve closure member is Isolated from the valve inlet. the retaining member being configured to rupture upon apphcation of a predetermined pressure to the second valve closure member, thereby allowing the second valve closure member to move out of engagement with the second valve seat and permitting communication of the first valve closure member with the inlet.
  2. 2. A pressure relief valve as claimed In claim 1, further comprising an elongate member extending from the second valve closure member.
  3. 3. A pressure relief valve as claimed in claim 2, wherein the elongate member extends from the rear face of a second valve closure member.
  4. 4. A pressure relief valve as claimed in claim 2 or claim 3, further comprising a first guide through which the elongate member extends, the retaining member engaging the elongate member and the guide to prevent relative displacement.
  5. 5. A pressure relief valve as claimed in claim 4, wherein the retaining member extends through aligned apertures in the elongate member and the guide.
  6. 6. A pressure relief valve as claimed in claim 4 or claim 5, wherein the elongate member passes sealingly through the first guide.
  7. 7. A pressure relief valve as claimed in any of claims 4 toS, wherein the first guide is tubular.
  8. B A pressure relief valve as claimed In any of the preceding claims, wherein the retaining member is configured to shear on application of a predetermined pressure to the second valve closure member.
  9. 9. A pressure relief valve as claimed in claim 8, wherein the retaning member comprises a pin.
  10. 10. A pressure relief valve as claimed in any of claims 4 to 9, further comprising second guide means through which the first guide means extends and one or more fusible retainer means which prevent relative movement of the first and second guide means below a predetermined temperature.
  11. 11. A pressure relief valve as claimed in claim 10, wherein the fusible retainer means comprises a fusible plug.
  12. 12. A pressure relief valve as claimed in claIm 2 or claIm 3. whereIn the elongate member forms the retaining member.
  13. 13. A pressure relief valve as claimed in claIm 12, wherein the retaining member is conflgwed to deform non-resiliently on application of a predetermined pressure to the second valve closure member.
  14. 14. A pressure relief valve as claimed in claim 13, wherein the retaining member comprises a buckle pin.
  15. 15. A pressure relief valve as claimed in any of claims 12 to 14, wherein the end of the elongate member remote from the second valve closure member Is secured to a mounting which is received in a guide fixed with respect to the valve body.
  16. 16. A pressure rehef valve as claimed in claim 15, whereIn the guide is tubular.
  17. 17. A pressure relief valve as claimed In claim 15 or 16, further comprising one or more fusible retainer means which prevent relative movement of the mounting and the guide means below a predetermined temperature.
  18. 18. A pressure relief valve as claimed in claim 17, wherein the fusible retainer means comprises a fusible plug.
  19. 19. A pressure Slat valve substantially as herein described with reference, and as iliustrated in, the accompanying drawings.G:\CUEWfl44O.445tFH3\442792kG8%Ma$ter dcc
GB1319097.0A 2013-10-29 2013-10-29 Pressure relief valve Withdrawn GB2519771A (en)

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GB2519771A true GB2519771A (en) 2015-05-06

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017129672A1 (en) * 2016-01-28 2017-08-03 Technip France Flexible line with flooded annular space

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2095371A (en) * 1981-03-23 1982-09-29 Anderson Greenwood & Co Pressure relief device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2095371A (en) * 1981-03-23 1982-09-29 Anderson Greenwood & Co Pressure relief device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017129672A1 (en) * 2016-01-28 2017-08-03 Technip France Flexible line with flooded annular space
FR3047292A1 (en) * 2016-01-28 2017-08-04 Technip France FLEXIBLE LINE WITH ANNULAR INONDE

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Publication number Publication date
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