Patent Publication Number: US-11662035-B1

Title: Oil-damped pressure release valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation of U.S. application Ser. No. 17/897,858, now allowed, having a filing date of Aug. 29, 2022. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure is directed to pressure relief valves; and more particularly to a pressure relief valve with improved stability during release of excessive pressure. 
     Description of Related Art 
     The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention. 
     Pressure relief valves (also known as safety valves) are used in many systems to relieve excessive pressure, for instance in many industrial applications to prevent plant operating systems from reaching dangerously high pressures. Such valves include a nozzle and a valve seat which is normally closed by a valve disc slidably disposed in a body of the valve (valve body). The valve disc typically is biased in a closed position against the valve seat by a spring (like a compression spring). Generally, the pressure relief valve is configured so that the lower surface of the nozzle receives the pressure of the gas or the steam tank from a lower inlet portion of the valve body so that the pressure is transmitted through the nozzle. The nozzle is in fluid communication with a pressurized medium in operative connection, and then is closed in the closed position of the pressure relief valve. 
     With the valve in the closed position, when the pressure in the nozzle exceeds a predefined set value, the valve disc “pops” open and places the nozzle in fluid communication with an exhaust port in the valve body, thus releasing the excessive pressure therefrom. Further, when the pressure in the nozzle decreases by a specified incremental amount, termed the blowdown differential or simply “blowdown” for the valve, the valve disc is again seated on the valve seat to dispose the valve back in its closed position. 
     One of the major issues with conventional pressure relief valves is the instability during releasing excessive pressure. In particular, the release of the excessive pressure may cause vibrations in the valve body of the pressure relief valve. These vibrations may result in mechanical waves that propagate through the valve body and the components arranged therein, and especially the valve disc which is directly exposed to excessive pressure. This, in turn, could displace the valve disc, thus affecting proper seating of the valve disc with respect to the nozzle, causing shuttering to the disc. Improper seating could result in a loss (leakage) of pressure from the valve body even in its closed position, which is undesirable. For example, in petrochemical industry with high pressure hydrocarbon gas systems, the leakage of the gases may be harmful in many cases, and may need to be burned in a flare causing financial loss as well as excessive pollution. 
     Some techniques have been proposed in the art to address this problem and improve the stability of pressure relief valves. For example, U.S. Pat. No. 5,261,450A describes a pressure relief vent for a tank or vessel to relieve a positive pressure difference between the interior and the exterior of the tank or vessel through an opening in such a manner that a steady rise in tank pressure above a set pressure will be relieved, but a transient, dynamic surge of pressure above the set pressure, such as a collision, an impact, or the like, will not cause the relief vent to open and allow the leakage of product. U.S. Pat. No. 4,858,642A provides a pressure operated relief valve comprising compressible shock absorber means interposed between the disc and disc holder, wherein the shock absorber functions to lessen the shock forces involved when the valve disc impacts upon valve seat at closing. KR Patent Publication No. 20100013392A provides a spring-activated safety valve to prevent a chattering effect when opening/closing a valve disc and to reduce the lifting impact of the valve disc, in which a disc holder is attached to the top of a disc, a damping chamber is provided by forming a space between the disc guides and guide the ascent and descent of the disk holder. 
     Each of the aforementioned references suffers from one or more drawbacks hindering their adoption. None of the references provides proper dampening of the valve disc due to the release of the excessive pressure, especially dampening the vibrations in the valve body of the pressure relief valve to prevent generation of the mechanical waves therein. Moreover, the proposed designs in the cited references may require major modifications in the design of the pressure relief valve and/or may compromise the working thereof. 
     It is an object of the present disclosure to provide a design for the relief valve device to dampen the vibrations due to sudden pop action of the valve disc while releasing the excessive pressure in order to prevent displacement of the valve disc with respect to the nozzle in the valve body, and further to make the valve disc to be faster and properly seated back on the nozzle when the excessive pressure has been released. 
     SUMMARY 
     In an exemplary embodiment, a relief valve device is provided. The relief valve device comprises a spring, a valve bonnet, a valve stem, a disc holder, a valve disc, a blowdown ring, and a nozzle. In the relief valve device, the valve disc is positioned above the nozzle. Further, the spring is disposed in the valve bonnet. Further, the spring surrounds the valve stem such that a longitudinal axis of the spring and a longitudinal axis of the valve stem are coaxial. Further, the disc holder surrounds an outer periphery of the valve disc and is adjacent and in direct contact with a surface of the valve disc around an entire perimeter of the valve disc. Further, the blowdown ring is disposed at a top section of the nozzle. Further, a bottom section of the nozzle is connected to a bottom surface of a valve body and the top section of the nozzle is connected to the valve disc. Furthermore, the disc holder is filled with oil. Herein, the relief valve device is configured such that flow through the nozzle is prevented when a first pressure at an inlet of the nozzle is below a predetermined force of the spring, and when the first pressure exceeds the predetermined force of the spring, the valve stem is moved linearly through an axis of the spring to displace the valve disc from sitting atop the nozzle and permit flow through the nozzle. 
     In one or more exemplary embodiments, the disc holder has a cylindrical stem section. In one or more exemplary embodiments, a diameter of the cylindrical stem section is from 0.6 to 0.8 times a length of the cylindrical base. In one or more exemplary embodiments, the oil is present in the cylindrical stem section of the disc holder, and the cylindrical stem is hollow along from 50% to 90% of an entire length of the cylindrical stem section. 
     In one or more exemplary embodiments, the disc holder has a cylindrical base. In one or more exemplary embodiments, the cylindrical base sits atop the valve disc. 
     In one or more exemplary embodiments, the disc holder is made of a metal. 
     In one or more exemplary embodiments, the disc holder, the blowdown ring, and an outer wall of the nozzle define the huddling chamber. 
     In one or more exemplary embodiments, the device comprises a process zone valve (PZV). In one or more exemplary embodiments, the PZV directs the oil to flow through the disc holder. 
     In one or more exemplary embodiments, the device further comprises a pressure adjusting screw configured above a top surface of the valve bonnet. In one or more exemplary embodiments, the pressure adjusting screw is configured to control the predetermined force of the spring. 
     In one or more exemplary embodiments, the valve stem is fluidically connected to the disc holder. 
     In one or more exemplary embodiments, the disc holder has a hollow cylindrical stem section and a hollow base portion. In one or more exemplary embodiments, the hollow cylindrical stem section and the hollow base portion define a continuous space. In one or more exemplary embodiments, both the hollow cylindrical stem section and the hollow base section are filled with oil. 
     The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure, and are not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of this disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG.  1    is a diagrammatic cross-sectional view illustration of a relief valve device, according to certain embodiments. 
         FIG.  2    is a simplified diagrammatic cross-sectional view illustration of a pressure relief valve. 
         FIG.  3    is a simplified diagrammatic cross-sectional view illustration of the relief valve device of  FIG.  1   , according to certain embodiments. 
         FIG.  4    is an exemplary flowchart listing steps involved in operation of the relief valve device of  FIG.  1   , according to certain embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the drawings, like reference numerals designate identical or corresponding parts throughout the several views. Further, as used herein, the words “a,” “an” and the like generally carry a meaning of “one or more,” unless stated otherwise. 
     Furthermore, the terms “approximately,” “approximate,” “about,” and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween. 
     Aspects of the present disclosure are directed to a relief valve device with a design to reduce instability of a valve disc therein, due to vibrations during release of excessive pressure therefrom, which may otherwise affect placement setting (reseating) of the valve disc with respect to a nozzle in the relief valve device and may, in turn, lead to pressure loss (leakage) during its operation. In particular, the present disclosure provides a relief valve having a valve disc supported by a disc holder having a hollow stem portion which is preferably at least partially filled with oil in order to dampen the effect of the vibrations when the relief valve is opened during an excessive pressure event. 
     Referring to  FIG.  1   , illustrated is a diagrammatic cross-sectional view of a relief valve device (represented by reference numeral  100 ); hereinafter, sometimes, simply referred to as “device  100 ” without any limitations. The relief valve device  100 , as described herein, is a pressure relief valve which is a type of relief valve, or generally safety valve, used to control or limit the pressure in a pressurized fluid system (hereinafter, referred to as “system,” not shown in drawings). Herein, the said system may be any of pneumatic and hydraulic systems which are used to control fluid variables, such as pressure, temperature and flow. The relief valve device  100  is used to respond to an overpressure event and avoid overpressure on an upstream side (high pressure side) of the relief valve in the system and thereby avoid damage to any upstream process, instrument or equipment failure. As used herein, the overpressure event may refer to any condition which may cause pressure in the system to increase beyond a specified design pressure. By use of the relief valve device  100 , the pressure in the system is relieved by allowing the pressurized fluid to flow from an auxiliary passage out of the system. The relief valve device  100  is designed or set to open at a predetermined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits. When the set pressure is exceeded, the relief valve device  100  opens to provide an auxiliary route for fluid escape or diversion thereby permitting at least a portion of the fluid to be diverted and provide pressure relief in the system. In some embodiments, the valve device  100  operates at a set pressure ranging from 20 pounds per square inch gauge (psig) to 2,500 psig, preferably 25 psig to 2,000 psig, preferably 30 psig to 1,500 psig, preferably 35 psig to 1,000 psig, preferably 35 psig to 500 psig, preferably 40 psig to 225 psig, preferably 50 psig to 200 psig, preferably 75 psig to 175 psig, preferably 100 psig to 150 psig, or 125 psig. In some embodiments, the valve device  100  operates between at least 1% and 30% above the set maximum operating pressure of the system, preferably 10% to 25%, preferably 15% to 20%, preferably 2% to 9%, preferably 3% to 8%, preferably 4% to 7%, or 5%. 
     As illustrated in  FIG.  1   , the relief valve device  100  includes a valve body  102 . The valve body  102  provides a housing to support various elements of the relief valve device  100 . The valve body  102 , also referred to as valve shell, is the primary pressure boundary of the relief valve device  100 . The valve body  102  serves as the principal element, providing the framework that holds the various elements of the relief valve device  100  together. For instance, the valve body  102  resists fluid pressure loads from connecting piping in the system, and receives inlet and outlet piping of the system through threaded, bolted, or welded joints. In one or more examples, the valve body  102  is made of metallic material, such as stainless steel, galvanized steel, iron, nickel, copper, aluminum, bronze, metal alloys, or the like. For present purposes, the valve body  102  may be casted or forged from the selected material into required shape, which is usually cylindrical or spherical. In some embodiments, the length of the forged valve body  102  is between 1.1 and 1.7 times greater than the length of an exhaust port or auxiliary passage, preferably 1.2 to 1.6 times greater, preferably 1.3 to 1.5 times greater, or 1.4 times greater. The length of the forged valve body  102  can be defined as the length between a top surface of an adjusting screw  116  to a nozzle  106 . The length of the exhaust port can be defined as the length of the opening in  FIG.  1    that is exposed to an external atmosphere. 
     Further, as illustrated, the valve body  102  provides a section in which different components responsible for releasing excessive pressure in the system are arranged, and such section is referred to as valve bonnet  104  (as shown in  FIG.  1   ). It may be understood that the valve bonnet  104  is preferably a unitary part of the valve body  102 ; however, in other examples, the valve bonnet  104  may be a separately casted or forged from same or different material as that of the valve body  102 , and is connected to the valve body  102  by a threaded, bolted, or welded joint. In some embodiments, the valve bonnet  104  is fabricated of brass, plastic, aluminum, steel, or the like. In some embodiments, the valve bonnet  104  is substantially cylindrical and has a diameter ranging from 2 inches to 8 inches, preferably 3 inches to 7 inches, preferably 4 inches to 6 inches, or 5 inches. The valve bonnet  104  has a top surface  104   a  and a bottom surface  104   b . In some embodiments, the length between the top surface  104   a  and bottom surface  104   b  ranges from 2 inches (in) to 16 in, preferably 4 in to 14 in, preferably 6 in to 12 in, or 10 inches. Further, the relief valve device  100  includes a nozzle  106  disposed in the valve bonnet  104 . Specifically, the nozzle  106  is disposed in the bottom surface  104   b  of the valve bonnet  104  and is fastened in the bonnet through a friction, threaded, bolted, or welded joint. The nozzle  106  has a top section  106   a  and a bottom section  106   b . The nozzle  106  is designed to connect the relief valve device  100  to the piping or equipment of the system. The nozzle  106  may use different types of end connections, such as butt or socket welded, threaded or flanged for such connection purposes. In some embodiments, the nozzle  106  can accommodate pressurized gas in a range from 10 pounds per square inch/minute (psi/min) to 100 psi/min, preferably 20 psi/min to 90 psi/min, preferably 30 psi/min to 80 psi/min, preferably 40 psi/min to 70 psi/min, preferably 50 psi/min to 60 psi/min, or 55 psi/min. In some embodiments, the length between the top section  106   a  and the bottom section  106   b  ranges between 1 inch and 6 inches, preferably 2 inches to 5 inches, preferably 3 inches to 4 inches, or 3.5 inches. In alternate embodiments, the nozzle  106  takes on a conical shape, inverted shape, convergent shape, ring shape, flat-tipped shape, or divergent shape. In some embodiments, the bottom section  106   b  of the nozzle  106  is connected to a bottom surface  104   b  of the valve bonnet  104  and the top section of the nozzle  106   a  is connected to the valve disc  110 . 
     The relief valve device  100  also includes a valve disc  110 . The valve disc  110  is a pressure-retaining part which provides the capability for permitting and prohibiting fluid flow in the relief valve device  100 , e.g., fluid flow from an upstream high pressure side to a low pressure downstream side. The valve disc  110  is typically forged and, in some designs, hard-surfaced to provide good wear characteristics. As shown in  FIG.  1   , in the relief valve device  100 , the valve disc  110  lies and is positioned above the nozzle  106  at the top section  106   a  and seals the downstream nozzle from the upstream portion of the valve. In one or more examples, the valve bonnet  104  may provide a seat or seal rings (not shown) to provide a seating surface for the valve disc  110 . In a configuration, the valve bonnet  104  is machined to serve as the seating surface and seal rings are not used. In another configuration, forged seal rings are threaded or welded to the valve bonnet  104  to provide the seating surface. In some embodiments, the valve disc  110  is forged of aluminum, steel, plastic, polymers, bronze, iron, nickel, or copper. In some embodiments, the length of the valve disc  110  is between 0.5 times to 0.8 times as great as the length of the valve bonnet  104 , preferably 0.55 to 0.75 times as great, preferably 0.6 to 0.7 times as great, or 0.65 times as great. In some embodiments, the valve disc  110  includes a recess sized between 0.25 inches and 1 inch in depth to form a connection with the valve bonnet  104 , preferably between 0.3 in to 0.9 in, preferably 0.4 in to 0.8 in, preferably 0.5 in to 0.7 in, or 0.6 in in depth. The relief valve device  100  further includes a valve stem  112  which is responsible for the proper positioning of the valve disc  110  in the valve bonnet  104 . The valve stem  112  also provides the necessary movement to the valve disc  110  for opening or closing of the relief valve device  100 . The valve stem  112  is typically forged separately, and is connected to the valve disc  110  by threaded or welded joints. In some embodiments, the valve stem  112  is forged of metal, plastic, ceramic, or a combination of the like. In some embodiments, the valve stem  112  has a length that is between 0.4 and 0.8 times the length between the top surface  104   a  and the bottom surface  104   b , preferably 0.45 to 0.75 times the length, preferably 0.5 to 0.7 times the length, preferably 0.55 to 0.65 times the length, or 0.6 times the length. In some embodiments, the valve stem  112  is substantially cylindrical and has a radius ranging from 0.2 inches to 0.6 inches, preferably 0.25 in to 0.55 in, preferably 0.3 in to 0.5 in, preferably 0.35 in to 0.45 in, or 0.4 inches in diameter. 
     According to embodiments of the present disclosure, as also shown in  FIG.  1   , the relief valve device  100  is a spring-loaded pressure relief valve. In such embodiments, the relief valve device  100  includes a spring  114 . In the illustrated example, the spring  114  is a helical spring; however, in other examples, the spring  114  may be use other type of compression springs, or even a diaphragm in some cases, without any limitations. In the relief valve device  100 , the spring  114  is selected to fit inside the valve bonnet  104 . As shown in  FIG.  1   , the spring  114  is disposed in the valve bonnet  104 . Further, as shown, the spring  114  surrounds a periphery of the valve stem  112 , such that the longitudinal axis of the spring  114  and longitudinal axis valve stem  112  are coaxial within the bonnet  104 . In the relief valve device  100 , the spring  114  is selected/designed for a set pressure of the relief valve device  100 ; i.e., to have a predetermined force of the spring. In some embodiments, the spring  114  is fabricated of a metal. In some embodiments, the spring  114  can stretch between 0.3 to 0.7 times the length of the valve bonnet  104 , preferably 0.35 to 0.65 times the length, preferably 0.4 to 0.6 times the length, preferably 0.45 to 0.55 times the length, or 0.5 times the length. The spring force at least partially defines the set-pressure threshold, which is the minimum pressure at the nozzle  106  required to overcome the spring force and move the valve disc  110  out of sealing engagement with the nozzle  106 . In some embodiments, the relief valve device  100  also includes a pressure adjusting screw  116 . The pressure adjusting screw  116  is configured to control the predetermined force of the spring  114 . This may be achieved by tightening or loosening the pressure adjusting screw  116 , as may be understood by a person skilled in the art. As shown, the pressure adjusting screw  116  is configured above the top surface  104   a  of the valve bonnet  104 . Such arrangement provides access to the pressure adjusting screw  116  from outside of the valve bonnet  104 , to allow for its adjustment as required. In some embodiments, the pressure adjusting screw  116  is forged of metal, metal alloys, plastics, or a combination of the like. In some embodiments, the pressure adjusting screw  116  is welded or molded to the valve bonnet  104  itself. In some embodiments, the pressure adjusting screw  116  is substantially cylindrical and has a diameter ranging from 0.1 to 0.4 times the diameter of the valve bonnet  104 , preferably 0.15 to 0.35 times the diameter, preferably 0.2 to 0.3 times the diameter, or 0.25 times the diameter. 
     Such design of the relief valve device  100  helps the spring  114  to be implemented for opening and closing of the relief valve device  100 . Herein, the relief valve device  100  is configured such that flow through the nozzle  106  is prevented when a first pressure at an inlet of the nozzle  106  is below the predetermined force of the spring  114 ; and when the first pressure exceeds the predetermined force of the spring  114 , the valve stem  112  is moved linearly through an axis of the spring  114  to displace the valve disc  110  from its position atop the nozzle  106  and permit flow from the valve body through the nozzle  106 . In some embodiments, the valve stem  112  can move linearly from 0.6 to 0.8 times the length between the top surface  104   a  and bottom surface  104   b , preferably 0.625 to 0.775 times the length, preferably 0.65 to 0.75 times the length, preferably 0.675 to 0.725 times the length, or 0.7 times the length. In some examples, the relief valve device  100  further includes a bonnet plug (not shown) disposed within the valve bonnet  104  at a side surface of the valve bonnet  104 . The bonnet plug helps to keep the pressure inside the valve bonnet  104  to be almost equal to atmospheric pressure at all times. Thus, the bonnet plug prevents flow through the nozzle  106  when the first pressure at the inlet of the nozzle  106  is below the predetermined force of the spring  114 . 
     In the present embodiments, the relief valve device  100  further includes a disc holder  120  which may be a distinct component separable from the valve disc  110  or integrated with the valve disc. In some embodiment the valve disc is a seating surface of the disc holder that seals the valve body from the nozzle and prevents fluid from leaving the valve body. The disc holder  120  is preferably designed to allow the valve disc  110  to float which provides play for an angular movement that reduces seat leakage from minor misalignments (ensuring that the valve disc  110  has 360 degrees of contact with the seat provided on the nozzle  106 ). 
     As shown in  FIG.  1   , in the relief valve device  100 , the disc holder  120  surrounds an outer periphery of the valve disc  110  and makes direct contact with a surface of the valve disc  110  around an entire perimeter of the valve disc  110 . In the present examples, the disc holder  120  is made of a metal. In other examples, the disc holder  120  is made of plastic, ceramic, polymers, or metal alloys. Generally, the disc holder  120  may be made of same material as the valve disc  110 . In an example, the disc holder  120 , similar to the valve disc  110 , may also be forged and, in some configurations, hard-surfaced to provide good wear characteristics. In some examples the lateral length of the disc holder  120  is 1.1 to 1.4 times the length of the valve disc  110 , preferably 1.15 to 1.35 times the length, preferably 1.2 to 1.3 times the length, or 1.25 times the length. In alternate embodiments, the disc holder  120  contains an adjustment ring to tightly seal the valve disc  110  to the disc holder  120  and is preferably made of a plastic or polymer. 
     The relief valve device  100  also includes a huddling chamber  122 . The huddling chamber  122  is around the periphery of the nozzle  106 , that aids in the relief valve in providing a snap opening. If a huddling chamber is too large, it can cause a blow-down value of a relief valve to be higher than desired. Thus, it may be desirable to scale the huddling chamber so that the valve snaps open, e.g., opens with the aid of force imparted or enhanced by the huddling chamber, but maintains a low blow down value. The disc holder  120 , a blowdown ring  124 , and outer wall of nozzle  106  are configured to provide the huddling chamber  122 . The huddling chamber is a space that is preferably defined by surfaces of the disc holder, the nozzle and the blowdown ring. As shown in  FIG.  1   , the huddling chamber is defined by bottom surfaces of the disc holder having both vertical and horizontal components, a top surface of the blowdown ring and a portion of a side surface of the nozzle. The huddling chamber preferably extends around the entire circumference of an outer surface of the nozzle in the form of a ring. Preferably, a portion of a side wall of the huddling chamber is at least partially open although in other embodiments openings may be provided by gaps in the blowdown ring. The huddling chamber  122  is a space in which a fluid gathers; specifically, an annular space under a projecting collar of the valve disc  110 , in which the fluid collects as soon as the relief valve device  100  opens. During operation of the relief valve device  100 , the fluid in the huddling chamber  122  preferably exerts force on the valve disc  110 , forcing the relief valve device  100  to open wider and to hold the relief valve device  100  open until the pressure on the upstream side of the valve drops. It may be appreciated that an outside diameter, shape and thickness of the disc holder  120  plays a role in defining the shape of the huddling chamber  122 , and thereby the initial lift and the performance of the relief valve device  100 . In some embodiments, the huddling chamber  122  contains a volume of fluid ranging from 0.1 mL to 250 mL, preferably 25 mL to 225 mL, preferably 50 mL to 200 mL, preferably 75 mL to 175 mL, preferably 100 mL to 150 mL, or 125 mL of fluid. In some embodiments, the valve disc  110  is hollow and its volume is filled with an oil. In some embodiments, the hollow section of the valve disc  110  may be continuous with a hollow portion of the valve stem  112  so that there is a continuous volume between the two components. In some embodiments, the hollow section of the valve disc  110  may not be continuous with a hollow portion of the valve stem  112  so that there is a physical barrier between the two components, separating two distinct volumes. 
     The relief valve device  100  further includes a blowdown ring  124 . In the relief valve device  100 , as shown in  FIG.  1   , the blowdown ring  124  is disposed at the top section  106   a  of the nozzle  106 . The blowdown ring  124  is an adjustable ring with a design shape that modifies the effluent flow path. It may be appreciated that the shape of the huddling chamber  122  may also be defined based on the size of the blowdown ring  124 . In the relief valve device  100 , as shown in  FIG.  1   , the blowdown ring  124  is threaded onto the nozzle  106 . In particular, the blowdown ring  124  is disposed at a top section  106   a  of the nozzle  106 . The blowdown ring  124  may be adjusted vertically up or down to a position relative to contact with the valve disc  110 . The position of the blowdown ring  124  may change the blowdown (or reseat) pressure; and the closer the blowdown ring  124  is to the nozzle  106 , the lower the pressure in the system will need to be for the relief valve device  100  to close (more blowdown). The position of the blowdown ring  124  in the valve bonnet  104  is fixed with a locking screw (not shown). In the relief valve device  100 , the blowdown ring  124  may also be swapped to different size or different shaped rings to adjust performance based on the expected relief fluid. In some embodiments, the blowdown ring  124  has a length from 0.1 to 0.4 times the length of the valve disc  110 , preferably 0.15 to 0.35 times the length, preferably 0.2 to 0.3 times the length, or 0.25 times the length. In some embodiments, the blowdown ring  124  is shaped of plastic or metal. In some embodiments, the blowdown ring is spaced away from top surface  106   a  of the valve disc  110  from between 0.05 inches or 0.3 inches, preferably 0.1 inches to 0.25 inches, or 0.175 inches. 
     It may be appreciated that the relief valve device  100  is generally modular. The internal parts for the relief valve device  100 , including the valve disc  110 , the disc holder  120 , the blowdown ring  124  may be interchanged for ones with a different design to customize performance of the relief valve device  100  based on the application, fluid service, and set pressure. In general, the shape of the huddling chamber  122  (created by the shape and size of the disc holder  120 ), the position and shape of the blowdown ring  124 , and the characteristics of the fluid being relieved together determine the initial opening force and the initial lift of the relief valve device  100 . The relief valve device  100  may have a “pop action” as it typically pops open at a preset pressure. The pop action occurs because the huddling chamber  122  is designed with an area that is approximately 10%-30% larger than the valve seat (as the disc holder  120  is bigger than the valve disc  110 ), preferably 12%-28%, preferably 14%-26%, preferably 16%-24%, preferably 18%-22%, or 20%. Once the pressure under the seat is enough to lift the valve disc  110  off the nozzle  106 , there is a step change in the upward force on the spring  114  and the relief valve device  100  pops open. Such sudden pop may cause vibration and consequently mechanical waves to propagate in the valve body  102 , which, in turn, may affect seating of the valve disc  110  with respect to the nozzle  106 . 
     In the present embodiments, the disc holder  120  has a stem portion  130 , preferably continuous or in mechanical communication with the valve stem  112 . As shown in  FIG.  1   , the stem portion  130  is extending upwards in the valve bonnet  104 , from the valve disc  110 . In particular, the stem portion  130  has a stem section  132  and a base section  134 . In an embodiment, the stem section  132  is a cylindrical stem section, with the two terms being interchangeably used hereinafter. That said, in other examples, the stem section  132  may have any other suitable shape, such as cylindrical cross-section, without any limitations. In some embodiments, the stem section  132  has a diameter that is between 1.1 and 1.3 times the diameter of the pressure adjusting screw  116 , preferably 1.15 to 1.25 times greater, or 1.2 times greater. In some embodiments, the stem section  132  is forged of metal, plastic, or ceramic. In some embodiments, the stem section has a length that is 0.3 to 0.6 times the length between  104   a  and  104   b  of the valve bonnet  104 , preferably 0.35 to 0.55 times greater, preferably 0.4 to 0.5 times greater, or 0.45 times greater. Further, in an embodiment, the base section  134  may be a cylindrical base section. That said, in other examples, the base section  134  may have any other suitable shape, such as circular cross-section, without any limitations. In the relief valve device  100 , as shown, the base section  134  sits atop the valve disc  110 . Further, the cylindrical stem section  132  extends upwards from the cylindrical base section  134 , forming the disc holder  120 . In an example, a diameter of the cylindrical stem section  132  is from 0.1 to 0.3 times a length of the cylindrical base section  134 , preferably 0.125 to 0.275 times a length, preferably 0.15 to 0.25 times a length, preferably 0.175 to 0.225 times a length, or 0.2 times a length. For instance, in a particular example, as may be seen from  FIG.  1   , the diameter of the cylindrical stem section  132  is 0.7 times the length of the cylindrical base section  134 . In some embodiments, the cylindrical base section  134  is made of metal, plastic, ceramic, or a combination of the like. 
     According to preferable embodiments of the present disclosure, the disc holder  120  may be at least partially hollow and filled with oil (as represented by reference numeral  136  in FIG.  1 ). In an embodiment, the disc holder  120  has a hollow cylindrical stem section  132 , and the oil  136  is present in the cylindrical stem section  132  of the disc holder  120 . In an embodiment, the disc holder  120  has a hollow cylindrical stem section  132  and a hollow base section  134 . Further, the hollow cylindrical stem section  132  and the hollow base section  134  define a continuous space, and both the hollow cylindrical stem section  132  and the hollow cylindrical base section  134  are filled with the oil  136 . In some embodiments, the total volume of the stem section  132  with the valve disc  110  is between 1.2 and 2 times greater than the total volume of the hollow space in the base section  134 , preferably 1.3 to 1.9 times greater, preferably 1.4 to 1.8 times greater, preferably 1.5 to 1.7 times greater, or 1.6 times greater. For purposes of the present disclosure, the oil  136  used to fill the disc holder  120  is a heavy oil, for example, but not limited to, mineral oil, polyalphaolefin, organophosphate ester and the like. Noncombustible inorganic oils are preferable for applications involving flammable fluids, e.g., silicon oils. In some embodiments, the oil  136  has a density from 800 kg/m 3  to 1400 kg/m 3 , preferably 900 kg/m 3  to 1300 kg/m 3 , preferably 1000 kg/m 3  to 1200 kg/m3, or 1100 kg/m 3 . In some embodiments, the oil  136  occupies between 60% and 100% of the volume within the cylindrical stem section, preferably 65% to 95%, preferably 70% to 90%, preferably 75% to 85%, or 80%. In some embodiments, the oil  136  has a dynamic viscosity ranging from 10 MPa-s to 50 MPa-s, preferably 20 MPa-s to 40 MPa-s, or 30 MPa-s. In some embodiments, the oil  136  has a specific gravity of from 0.82 to 0.94, preferably 0.84 to 0.92, preferably 0.86 to 0.9, or 0.88. In some embodiments, the cylindrical stem section  132  is hollow along from 50% to 90% of an entire length of the cylindrical stem section  132 , preferably between 60% and 80%, or 70%. The oil preferably has a viscosity of 40-150 cSt at 40 C, preferably 60-120 cSt or preferably 80-100 cSt. It may be appreciated by a person skilled in the art that the heavy oil is used as these are highly incompressible and may thus be better suited for providing the dampening effect in the relief valve device  100 . 
     In the relief valve device  100 , when the valve disc  110  may be subjected to vibration due to push from release of excessive pressure of the fluid from the nozzle  106 , the oil  136  in the disc holder  120  may help to dampen such vibrations, thus minimizing propagation of mechanical vibrations in the relief valve device  100  and preventing risk of the valve disc  110  being displaced and not being properly seated onto the nozzle  106 . Further, the proposed design with the oil  136  being present in both the hollow cylindrical stem section  132  and the hollow cylindrical base section  134  may provide enhanced dampening effect for vibrations in the valve disc  110 . Further, in some embodiments, the valve stem  112  is fluidly connected to the disc holder  120 . In such case, the oil  136  from the disc holder  120  may also be passed to the valve stem  112 . The valve stem  112  is in direct or indirect mechanical connection with the valve disc  110  and with the oil  136  present therein, may provide a relatively enhanced dampening effect for vibrations in the valve disc  110 . 
     Referring to  FIG.  2   , illustrated is a simplified diagrammatic cross-sectional view of a disc holder and stem section (as represented by reference numeral  200 ) with a valve disc  202 . As shown, the design of the disc holder and stem section  200  does not provide any section which may be filled with a fluid (such as, oil) to enable dampening of generated vibrations in the valve disc  202  therein. Referring to  FIG.  3   , illustrated is a simplified diagrammatic cross-sectional view of a disc holder and stem section (as represented by reference numeral  300 , and is similar in design to the disc holder  120  and stem section  132  of  FIG.  1   ) with a valve disc  302 , according to certain embodiments of the present disclosure. As shown, the design of the disc holder and stem section  300  provide a disc holder  304  supporting the valve disc  302 . The disc holder  304  is hollow to allow to its empty volume be filled with a fluid (such as, the oil  136 ) to enable dampening of generated vibrations in the valve disc  302  therein. 
       FIG.  4    is an exemplary flowchart  400  listing steps involved in operation of the relief valve device  100  of  FIG.  1   , according to certain embodiments. Herein, the steps of the flowchart  400  of  FIG.  4    have been explained with reference to described elements in the preceding paragraphs. Initially, a pressurized fluid is set below the valve disc  110  under force from the spring  114 , as described in step  402 . The pressurized fluid may build up below the valve disc  110  to exceed the predetermined force of the spring  114 . In some embodiments, the fluid builds up to at most 105% to 115% of the predetermined force of the spring, preferably 106% to 114%, preferably 107% to 113%, preferably 108% to 112%, preferably 109% to 111%, or 110%. The excessive pressure from the fluid, exceeding the predetermined force of the spring  114 , may push the valve disc  110  to cause the relief valve device  100  to open, as described in step  404 . The force due to the excessive pressure may be resisted by the valve disc  110  resulting in the valve disc  110  undergoing vibration (also known as valve chatter), as described in step  406 . At step  408 , the relief valve device  100  with the oil  136  present in the disc holder  120  dampens the generated vibrations in the valve disc  110  as explained in the preceding paragraphs. In particular, because of the pop action of the valve disc  110 , the oil  136  may move upwards in the disc holder  120  to absorb vibrations, and in turn may cause faster and proper seating of the valve disc  110  back on to the nozzle  106  when the excessive pressure is released. 
     Thus, the design of the relief valve device  100  of the present disclosure may help to overcome the instability issues due to vibrations in the pressure relief valves during release of excessive pressure therefrom, and thereby prevent possible mechanical failures, such as improper seating of the valve disc due to displacement thereof with respect to the nozzle by augmenting damping effect via use of oil in the disc holder  120 . The relief valve device  100  of the present disclosure with the above described features may particularly be useful in high pressure applications, such as gas industry (like hydrocarbon gases), HVAC industry, aerospace industry, and the like. In an embodiment, the relief valve device  100  may include a process zone valve (PZV). In other words, the relief valve device  100  is a process zone valve (PZV) which is widely used in the gas industry. The PZV directs the oil  136  to flow through the disc holder  120  to minimize vibrations, and cause faster and proper seating of the valve disc  110  back onto the nozzle  106  when the excessive pressure is released. This may reduce loss of the gases from the PZV valve and thus help in reducing the amount of burning of lost (exhausted) gases in the flare, saving the product from wastage at the same time, and further reducing the amount of pollution from the gases that may otherwise be burned. In some embodiments, the PZV is sized so the operating pressure does not exceed at most 10% of set valve pressure. In some embodiments, the PZV is fabricated of metal or plastic. In some embodiments, the PZV can direct flows ranging from 10 pounds per square inch/minute (psi/min) to 100 psi/min, preferably 20 psi/min to 90 psi/min, preferably 30 psi/min to 80 psi/min, preferably 40 psi/min to 70 psi/min, preferably 50 psi/min to 60 psi/min, or 55 psi/min. 
     Obviously, numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.