WO2008025936A1

WO2008025936A1 - A pressure relief valve and a method for relieving pressure from a system comprising a mud pump

Info

Publication number: WO2008025936A1
Application number: PCT/GB2006/050479
Authority: WO
Inventors: Tab S. Tettleton; Ernest Floyd Cox
Original assignee: Varco I/P, Inc.; Lucas, Brian
Priority date: 2006-08-31
Filing date: 2006-12-28
Publication date: 2008-03-06
Also published as: US20080078586A1

Abstract

A pressure relief valve comprising a body (126) with an inlet passageway (130) and an outlet passageway (140) and a valve member (148,153) for selectively controlling fluid flow from the inlet passageway (130) to the outlet passageway (140) , at least a part of said valve member (148,153) movable into the outlet passageway (140) to prevent fluid flow from the inlet passageway (130) through the outlet passageway (140) , the pressure relief valve further comprising a wear member (128) around a portion of an entrance end of the outlet passageway (140) , the body (126) having an interiorly threaded portion at the entrance of the outlet passageway (140) , the wear member (128) having an exteriorly threaded portion, the wear member releasably secured to the body (126) by threaded engagement of the wear member's exteriorly threaded portion with the body's interiorly threaded portion..

Description

A PRESSURE RELIEF VALVE AND A METHOD FOR RELIEVING

PRESSURE FROM A SYSTEM COMPRISING A MUD PUMP The invention relates to a pressure relief valve and a method for relieving pressure from a system comprising a mud pump.

In the drilling of a borehole in the construction of an oil or gas well , a drill bit is arranged on the end of a drill string, which is rotated to bore the borehole through a formation. A drilling fluid known as "drilling mud" is pumped through the drill string to the drill bit to lubricate the drill bit. The drilling mud is also used to carry cuttings produced by the drill bit and other solids to the surface through an annulus formed between the drill string and the borehole . The drilling mud may also be used to drive downhole drilling motors and to control down hole tools using the flow of drilling fluid and/or the pressure of the drilling fluid to power or activate the motor or downhole tool. The density of the drilling mud is closely controlled to inhibit the borehole from collapse and to ensure that drilling is carried out optimally. The density of the drilling mud effects the rate of penetration of the drill bit through the formation. By adjusting the density of the drilling mud, the rate of penetration changes at the possible detriment of collapsing the borehole . Commonly used drilling fluids are either water-based or oil based fluids . They can also contain a variety of additives which provide desired viscosity, lubricating characteristics, heat, anti corrosion and other performance characteristics. The drilling mud may also comprise lost circulation material . The lost circulation material is circulated in the drilling mud past any zones which are porous . Drilling fluid flows through the porous formation carrying with it lost circulation material which blocks the porous zone . Thus , the drilling mud contains expensive synthetic oil-based lubricants and it is normal therefore to recover and re-use the used drilling mud, but this requires the solids to be removed from the drilling mud. This is achieved by processing the drilling fluid. The first part of the process is to separate the solids from the solids laden drilling mud. This is at least partly achieved with a vibratory separator, such as those shale shakers disclosed in US 5,265,730, WO 96/33792 and WO 98/16328. The solids are covered in contaminates and residues. Further processing equipment such as centrifuges and hydrocyclones may be used to further clean the mud of solids. The clean mud is then retained in a mud tank or other vessel . When required, the clean mud is drawn from the mud tank and back through the drill string and the loop repeated. A mud pump may be used to pump drilling mud from the surface through the drill string, out through or near the drill bit and up through the annulus back to the top of the well.

In certain typical wellbore drilling situations using a drilling rig, drilling mud is pumped by a pumping system with one or more "mud" pumps . The mud pump system may include a triplex mud pump . The mud pump system delivers a large volume of mud flow under pressure for operations of the drilling rig. The mud is delivered to the drill string to flow down the string of drill pipe and out through the drill bit appended to the lower end of the drill string. It flows through the drill bit. The flow of mud cools the drill bit and reduces the temperature so that it lasts longer. Also, in certain situations, the mud flow is jetted out through a set of openings in the drill bit so that the mud hydraulically washes away the face of the well borehole if it is formed of soft materials. In addition, it washes away debris, rock chips and cuttings which are generated as the drill bit advances. Then, the mud flow returns to the surface in an annular space on the outside of the drill stem and on the interior of the open hole formed by the drilling process. While portions of the borehole may be cased from the surface, is of sufficient velocity that the mud is returned to the surface so that debris, chips and cuttings which are heavier than the mud are moved to the surface. This requires a substantial flow velocity. The drilling mud also cools the drill bit, which requires the drilling mud to travel at a substantial velocity. A relatively high volume of drilling mud is needed to achieve these flow velocities. Typical mud pump systems can deliver 1.9 to 3.8 cubic metres per minute (500 to

1,000 gallons per minute) through the drill string.

The flow of drilling mud must be delivered under control. The mud pump system can be required to deliver mud flow at 69 bars (1,000 psi) and higher. The wellhead pressures at the pump must be much higher if there is substantial flow pressure resistance along the flow path. The pump therefore is often operated at a very high pressure . The drill string in a deep well is an impediment to flow, thereby resulting in higher back pressures . The impediment to flow is overcome by applying greater pressures at the surface. In this regard, the mud pump system can typically be operated at pressures as high as 345 bars (5,000 psi) output. Because of the great variety of circumstances in which the drilling rig may be used, the output pressure of the mud pump may vary widely. In one aspect, the mud pump output pressure varies with the change in pump speed. Mud pumps can operate with pressure peaks that can be excursions as great as 14 bars or 21 bars (200 or 300 psi) on top of the prevailing baseline pressure. Thus mud pump output pressure can vary significantly.

The prior art discloses a variety of mud systems, relief valves and regulators , and systems to control and stabilize the pressure downstream of mud pump systems ; see, for example, and not by way of limitation, U.S. Patents 5,063,776; 5,616,009; 5,975,129; 7,055,623; 5,715,861; 4,638,978; and in U.S. Application Ser. No. 11/098,166 filed 04/04/2005 (co-owned with the present invention) , all incorporated fully herein for all purposes. In many prior art systems, a mud pump output manifold is input to a pressure relief valve which is operated so that the output pressure is controlled to a desired level , thus allowing a mud pump system to operate with a controlled pressure level to insure that the pressure experienced down hole at the drill bit and in the formations penetrated by the drill bit is regulated and to protect the mud pump system itself.

Various operations involve the use of pressurized systems and/or devices . For example , many different components used in the petroleum drilling and production industries , such as fluid pumps and mud pumps , are used in pressurized systems and subject to potentially significant internal fluid pressures . It is often desirable or necessary to relieve these systems and devices from excessive pressure to prevent equipment damage and failure, personal injury or for other reasons. To assist in relieving undesirable fluid pressure in pressurized systems and devices, pressure relief technology is commonly used. Currently available versions of pressure relief valves, systems and methods have various disadvantages. For example, the inventors have noted that many pressure relief valves wear and fail quickly due to high pressure fluid passing therethrough. For another example, various versions of pressure relief valves are large and bulky and require extensive space for operation. For still another example, many pressure relief valves are difficult to disassemble for servicing and maintenance . For an even further example, some pressure relief valves throttle between open and closed positions during operation, which is undesirable in many applications. For still another example, some pressure relief valves are purely mechanical in operation, which may contribute to inaccurate valve operation and overall poor or erratic performance. There are yet other potential disadvantages of presently available pressure relief valves , systems and methods. It should be understood, however, that each embodiment of the present invention and each claim of this patent does not necessarily address or solve every, or any particular, disadvantage of the existing technology.

Thus , there remains a need for pressure relief valve assemblies, systems and methods having one or more of the following attributes , capabilities or features : may be easily disassembled and reassembled; is easy to inspect and service, adjust and/or repair in the field; allows for the repair and replacement of internal valve components without removing the valve body from the line or equipment to which it is attached; has reduced likelihood of damage to internal valve components when discharging fluids; is not difficult to manufacture; includes a valve that is easily opened to allow access for inspection or removal of internal components; includes a valve having an angle-body configuration and/or a fluid flow path with approximately a ninety degree turn; includes a valve having a "flow-to-close" and/or a "fail-to-open" arrangement; includes a valve that opens rapidly and resets easily; includes a snap or pop acting valve; includes a valve having increased longevity; includes a valve that does not throttle between open and closed positions so that when the fluid pressure in the pressurized device is too high, the valve stays fully open until closed; includes a valve actuator that is integral to the valve; includes a reciprocating valve actuator stem or piston that does not protrude from the valve assembly; includes a valve actuator that is electronically controllable; includes an actuator piston engaged with and moveable on the same axis as the valve piston; includes an actuator piston actuated based upon the actual measured pressure of fluid in the pressurized device or system; includes a solenoid valve useful to assist in controlling movement of an actuator piston; includes a valve piston and/or actuator piston that is mechanically-biased in one direction; includes a valve piston and/or actuator piston that is controllably movable in one direction by fluid pressure; includes a valve piston and/or actuator piston that is internally sealed without metal seating; or any combination thereof.

In accordance with the present invention, there is provided a pressure relief valve comprising a body with an inlet passageway and an outlet passageway and a valve member for selectively controlling fluid flow from the inlet passageway to the outlet passageway, at least a part of said valve member movable into the outlet passageway to prevent fluid flow from the inlet passageway through the outlet passageway, the pressure relief valve further comprising a wear member around a portion of an entrance end of the outlet passageway, the body having an interiorly threaded portion at the entrance of the outlet passageway, the wear member having an exteriorly threaded portion, the wear member releasably secured to the body by threaded engagement of the wear member's exteriorly threaded portion with the body' s interiorly threaded portion . Preferably, the valve member is arranged within the body. Advantageously, the valve member has an exterior surface and said wear member has an interior surface, said valve member movable within and sealingly contacting the interior surface of the wear member. Preferably, said outlet passageway has a length, the wear member extending into the outlet passageway a distance less than the length of the outlet passageway. Advantageously, the wear member has a length which is less than half the length of the outlet passageway. Preferably, the pressure relief valve further comprises an actuator for selectively moving the valve member into the wear member. Advantageously, the body comprises an opening for receiving a part of the actuator, the opening of sufficient size such that upon removal of the actuator the wear member is accessible therethrough for installation and removal thereof. Preferably, the actuator comprises an actuator housing connected to the body. Advantageously, the actuator housing has a flange, the flange having bolt holes therethrough, the flange releasably bolted to the body. Preferably, the actuator housing comprises a guide for guiding the valve member. Preferably, the guide is in the form of a hole through the actuator housing. Preferably, the actuator includes an actuator piston that is fluid-powered in at least one direction. When the actuator piston is fluid-powered in only one direction, it is mechanically-biased in the opposite direction. The actuator piston is connected with, and movable along the same axis as, the valve piston. Preferably, a remotely-operated directional control valve is associated with the actuator and useful for directing fluid power to allow the actuator piston to move from an extended position to a retracted position, causing the valve piston to move from a closed position to an open position .

Advantageously, the pressure relief valve further comprises a valve stem connected to the valve member. Preferably, the valve stem passes through and is slideable within a hole in the actuator housing. Advantageously, the valve stem is fixed to a piston. Preferably, the piston is arranged in a cylinder, and a means for maintaining said valve member in a closed position to inhibit flow of fluid from said inlet passageway to said outlet passageway. Advantageously, said means comprises one of: a pneumatic fluid; a hydraulic fluid; and a combination of pneumatic and hydraulic fluids. Preferably, the cylinder is provided with a cylinder head. Advantageously, the cylinder comprises a fluid inlet and outlet port. Advantageously, the inlet and outlet port is one port used for allowing fluid to selectively flow into and out from the cylinder. Alternatively, separate inlet and outlet ports are provided.

Preferably, the valve member has a proximal end connected to the valve stem and a cap at said proximal end. Preferably, the cap has a central opening having an internal thread and the piston rod has an external thread to which the cap is screwed.

Advantageously, the actuator is provided with a resilient means to bias the valve member to an open position to allow fluid to flow from the inlet passageway to the outlet passageway. Preferably, the resilient means comprises at least one spring. Advantageously, the resilient means comprises at least two nested springs. Preferably, the springs are coiled springs of different sizes such that one spring sits inside of the other to form a pair of nested coiled springs .

Preferably, the pressure relief valve further comprises an indicator for indicating the position of the valve member. Open allowing fluid to communicate from the inlet passageway to the outlet passageway and hence relieve pressure or closed inhibiting fluid to flow from the inlet passageway to the outlet passageway, maintaining fluid in the system to which the pressure relief valve is connected. Advantageously, the indicator comprises a pin fixed to the valve stem. Preferably, the pin is arranged in a slot in the actuator housing.

Advantageously, the valve member comprises a cap at the distal end of the valve member. Preferably, the cap is domed or has a chamfered perimeter. Advantageously, the inlet passageway is arranged at an angle to the outlet passageway, such that the actuator can operate the valve member substantially in line with the flow of fluid through the outlet passageway. Preferably, the inlet passageway is arranged substantially at right angles to the outlet passageway.

Advantageously, the pressure relief valve further comprises a controller for selectively moving the valve member. Preferably, the controller includes an automatic reset function to automatically move the valve member to a closed position following the activation of the valve member acting to relieve pressure. Advantageously, the controller is programmable to reset at least one of a plurality of different measured pressures at the inlet passageway. Preferably, the controller resets the pressure relief valve assembly automatically. Advantageously, the pressure relief valve assembly is resettable manually. Advantageously, the wear member is made of INCONEL material .

Preferably, the valve member is located in an enlarged cavity between the inlet passageway and the outlet cavity, such that throttling is inhibited about the valve member.

The present invention also provides a drilling mud apparatus incorporating a pressure relief valve of the invention. Preferably, the drilling mud comprises at least one mud pump. The present invention also provides a method for changing a wear member in a pressure relief valve, the pressure relief valve comprising a body having an inlet passageway and an outlet passageway, the wear member arranged at an entrance to the outlet passageway, a valve member arranged for selective movement into and from the wear member and an actuator for actuating the valve member into and from the wear member to selectively allow and inhibit fluid to be relieved from the inlet passageway to the outlet passageway, the method comprising the steps of removing the actuator from the body to gain access to the wear member .

Preferably, the wear member is threaded to the body, the method further comprising the step of unscrewing the wear member from the body.

The present invention also provides a method for relieving pressure using a pressure relief valve in a system incorporating a mud pump, the pressure relief valve comprising an inlet passageway, an outlet passageway, a valve member and an actuator for actuating the valve member to selectively allow and inhibit fluid to be relieved from the inlet passageway to the outlet passageway, the method comprising the steps of maintaining fluid under pressure in a cylinder of the actuator to maintain the valve member in a closed position to inhibit fluid to pass from an inlet passageway to an outlet passageway and upon pressure rising to a predetermined threshold in said system, relieving the pressure in the cylinder to allow the pressure relief valve to open to allow fluid to be relieved from the inlet passageway to the outlet passageway.

The present invention also provides a pressure relief valve comprising a body having an inlet passageway, an outlet passageway, a valve member and an actuator for moving the valve member into and from the wear member to selectively allow and inhibit fluid to be relieved from the inlet passageway to the outlet passageway, wherein the valve member is movable in a direction substantially in line with the flow of fluid through the outlet passageway. Preferably, the inlet passageway is arranged at an angle to the outlet passageway, such that the actuator can operate the valve member substantially in line with the flow of fluid through the outlet passageway.

The present invention also provides a pressure relief valve comprising a body having an inlet passageway, an outlet passageway, a valve member and an actuator for moving the valve member into and from the wear member to selectively allow and inhibit fluid to be relieved from the inlet passageway to the outlet passageway, wherein the outlet passageway is arranged at substantially right angles from the inlet passageway.

Preferably, the pressure relief valve includes an angle-body valve having a valve piston disposed therein and being movable between at least one closed position and at least one open position. The closed position of the valve piston prevents fluid flow through the valve from the pressurized device and the open position allows fluid flow through the valve from the pressurized device.

Advantageously, at least one electronic pressure measuring device is separate from and associated with certain embodiments of the remotely-operated directional control valve and monitors pressure within the pressurized device. The position of the remotely- operated directional control valve is varied based upon power supplied to the control valve that is based upon at least one reading taken by the electronic pressure measuring device.

In some embodiments , a pressure relief valve assembly useful for relieving fluid pressure in a pressurized device includes an unintelligent angle-body valve having a flow-to-close arrangement. The valve includes a valve piston capable of moving between open and closed positions. The valve piston in the open position allows venting of fluid from the pressurized device through the valve. Movement of the valve piston into an open position does not depend upon internal fluid pressure within the unintelligent angle-body valve. At least one electronic pressure measuring device is capable of monitoring pressure within the pressurized device. An electronic controller is capable of causing the opening and closing of the valve piston based upon pressure readings of the electronic pressure measuring device.

For a better understanding of the present invention, by way of example, reference will now be made to the accompanying drawings in which:

Figure 1 is a schematic diagram of a system in accordance with the present invention with a relief valve in accordance with the present invention;

Figure 2 is a schematic diagram of a system in accordance with the present invention with a relief valve in accordance with the present invention; Figure 3A is a perspective sectional view of a relief valve in accordance with the present invention shown in a first stage of operation;

Figure 3B is a sectional view of the relief valve shown in Figure 3A; Figure 3C is a sectional view of part of the relief valve shown in Figure 3A in a second stage of operation;

Figure 4A is an end view of an insert used in the relief valve shown in Figure 3A;

Figure 4B is a cross-section view of the insert shown in Figure 4A taken along line 4B-4B;

Figure 5A is an end view of part of the relief valve shown in Figure 3A;

Figure 5B is a cross-section view of the part shown in Figure 5A taken along line 5B-5B; Figure 6A is an end view of part of the relief valve shown in Figure 3A; and

Figure 6B is a cross-section view of the part shown in Figure 6A taken along line 6B-6B.

Referring to Figure 1 , a system S in accordance with the present invention includes a mud system M with mud pits 28 for containing and storing drilling fluid; mud pumps 16 for pumping the drilling fluid to drill string

18 and back to the mud pits 28; and a relief valve 8 in accordance with the present invention for relieving pressure in the system. The drilling fluid or "mud" flows down the drill string 18 and then up in an annulus

20 between casing 22 and the drill string 18 to a bell nipple 24. The mud then flows in a return line 26 to the mud pits 18.

Initially mud flows into the valve 8 through a line

21 that is in communication with the line 19. A pressure sensor 23 senses a signal indicative of the pressure in the line 19, via the line 21, to a control system 14 which controls operation of the valve 8 and controls an air supply 12 which provides air under pressure to maintain the valve 8 closed until a pre-selected mud pressure is exceeded. When the mud pressure exceeds the pre-selected pressure, the valve 8 opens and the mud that was previously flowing to the drill stem 18 flows through the inlet 13 of the valve 8 and exits through an outlet 15 into an exit line 17. When pressure in the line 19 again falls below the pre-selected pressure, the control system 14 signals the air supply 12 to close the valve 8 (as will be described in more detail for certain embodiments described below) .

Figure 2 shows schematically the mud flow path for the system M. As shown in Figure 2, the system M (like numerals indicate like parts) includes a degasser 25 which reduces the gas content of the mud. In certain aspects, the control system ("CONTROLLER") includes an automatic reset function and also permits manual resetting ("ReSet," Figure 2), e.g. to re-close the valve after it has relieved pressure; and/or the possibility of two settings ("Hi," "Low," Figure 2) corresponding to two different pressure setpoints (e.g. a high setting, e.g. 520 bars (7500 psi) , at which the valve opens for relief and a low setting, e.g. below 28 bars (400 psi)). The valve is operable by manually pressing an "Operate" button. The controller can be a computerized system and/or PLC appropriately programmed. Referring now to Figures 3A to 3C, a relief valve 100 (one embodiment of the relief valve 8, Figure 1) includes a valve 120 and an actuator 160. In the embodiment shown, the valve 120 is an angle-body, two-way valve that includes a valve body 126 having intersecting first and second passageways 130, 140. The first passageway 130 is in fluid communication with a pressurized device (not shown) (e.g. a mud pump or pumps) and allows fluid flow (arrow 131) into the valve body 126 from the pressurized device. The second passageway 140 extends to an exit port 144 , allowing the exhaust (arrow 146) of fluid from the valve body 126. In an "angle- body" valve, the axis of the first passageway 130 is not concentric or coaxial with, but is approximately in the same plane as, the axis of the second passageway 140. An actuator housing 164 of the actuator 160 is connected to valve body studs 169.

A valve piston 148 is disposed at least partially within the second passageway 140 and serves to selectively control the flow of fluid from the first passageway 130 into the second passageway 140. The valve piston 148 is movable between "open" and "closed" positions relative to the first passageway 130. In a "closed" position, such as shown in Figures 3A and 3B, the exemplary valve piston 148 blocks the first passageway 130, preventing fluid flow from the first passageway 130 into the second passageway 140. When the valve piston 148 is in an "open" position, the first and second passageways 130, 140 are in fluid communication, allowing the flow of fluid from the first passageway 130

(and pressurized device) into the second passageway 140

(and out the exit port 144) . The valve 120 of the illustrated embodiment has a "flow-to-close" arrangement in which fluid flows through the second passageway 140 in the same direction as the movement made by the valve piston 148 going to its closed position.

The valve piston 148 has a removable cap 153 which is threadedly connected to an end of the valve piston 148. Optionally the cap 153 has an inclined or bevelled end surface 151 with holes 154 for facilitating piston installation. An exterior surface 157 of the cap 153 abuts an interior surface 121 of a seal insert 128.

The seal insert 128 (or, in one aspect a "wear member") is threadedly and removably secured in the body 126. In one particular aspect, the seal insert 128 is made of Inconel material due to the high wear area at the beginning of the passageway 140 at which the seal insert 128 is located. In certain aspects, the seal insert's length is considerably less than the length of the passageway 140 and, in one particular aspect, less than half said length.

The valve piston 148 has an edge 147. The seal insert 128 is sized with a sufficient length to encounter the initial highly abrasive flow of fluid at high speed from the passageway 130 to the passageway 140. Once this fluid exits the seal insert 128 it slows sufficiently so that the remainder of the interior of the passageway 140 (not protected by the seal insert 128) is not seriously worn or damaged. A seal 149 seals a valve-piston- 148/actuator-housing-164 interface .

The seal insert 128 has a male threaded portion which engages with a female threaded portion in the body 126 of the pressure relief valve 100. This facilitates repair and replacement of the seal insert 128

By unbolting the actuator 160 (by removing bolts 169) from the valve body 126, and removing valve piston 148 with its cap 153 from the passageway 140, the seal insert 128 can be removed from the valve body 126 for repair or replacement. The seal insert 128 can simply be unscrewed from engagement with the valve body 126.

A seal 122 in a recess 157 seals a seal-insert 128/valve-body-126 interface. Holes 123 facilitate installation of the seal insert 128. Holes 152 in a cap 139 facilitate installation of the cap 139.

The actuator housing 164 has a central cavity 170 within which an actuator piston 174 is moveable. The exemplary central cavity 170 is aligned with the second passageway 140 of the valve body 26. The actuator piston 174 connects to the valve piston 148 and moves it between open and closed positions. In the example shown, an actuator stem 180 connects the actuator piston 174 with a valve stem 150 extending from the valve piston 148, all of which move on the same axis. The cap 139 is threadedly secured around the valve stem 150.

The actuator stem 180 and valve stem 150 are releasably connected together with a releasable latch pin 156 to allow quick disconnection and replacement of the valve piston 148 without disturbing the actuator 160. The illustrated latch pin 156 extends through an opening 158 in the actuator housing 164 to allow for unencumbered movement of the latch pin 156 concurrent with reciprocation of the stems 150, 180.

The actuator piston 174 may be actuated in any desired manner. In the embodiment shown in Figure 3A, the actuator piston 174 is single acting, being fluid- powered in one direction (e.g. by pneumatic or hydraulic pressure) and mechanically-biased in the opposite direction. In one aspect when the pressurized device is a mud pump or pumps, the power fluid is air, e.g. air supplied by a rig air supply. For example, air or pneumatic pressure may be provided from an external source (not shown) into an outer portion 172 of the central cavity 170 of the actuator housing 164 to act upon an outer side 178 of the actuator piston 174 and move and hold the actuator piston 174 in an "extended" position and the valve piston 148 in a closed position

(e.g. Figure 3A) . In the illustrated embodiment, in one normal operating state of the valve assembly 100 has the actuator piston 174 in an extended position and the valve piston 148 in a closed position.

The mechanical-biasing force on the actuator piston 174 (and effectively on the valve piston 148) , when included, may be provided in any suitable manner. For example, one or more spring element or spring-like devices may be used to provide the sufficient biasing forces on the actuator piston 174 and move and hold the actuator piston 174 in a retracted position and the valve piston 148 in an open position, regardless of the system pressure or fluid pressure in the valve assembly 100. In the embodiment of Figure 3A, for example, outer and inner nested compression springs 184, 186, respectively, are shown disposed around the actuator stem 180 in the central cavity 170. The springs 184, 186 act on the inner side 176 of the actuator piston 174 to move and hold the actuator piston 174 in a "retracted" position (and the valve piston 148 in an open position) . The use of dual nested springs may be included, for example, to provide adequate biasing forces in the small area of the central cavity 170 sufficient to move the actuator piston 174 and the valve piston 148. In the embodiment shown, the springs 184, 186 provide sufficient biasing force to overcome multiple sealing engagements, such as at the seals 134 and 149. However, the present invention is not limited to fluid-powering in only one direction, the use of mechanical-biasing forces or the use of one or more spring element to provide mechanical- biasing force on the actuator piston and/or the valve piston.

If desired, one or more devices may be included for cushioning any contact of the actuator piston 174 with other components during its movement. For example, in Figure 3A, an elastomeric cushion ring 181 is disposed in an actuator end cap 182 to cushion contact of the actuator piston 174 with the end cap 182.

In another independent aspect of the invention, the actuator 160 may be controlled to move the valve piston 148 between open and closed positions in any desired manner. For example, referring to Figure 3A, the actuator 160 may be controlled based upon the fluid pressure within, or coming from, the pressurized device

(not shown) , referred to herein and throughout this patent as the "relevant pressure." Such a control scheme is referred to herein and throughout this patent as a "pressure-based" system. For example, when the valve assembly 100 of Figure 3A is used with a fluid pump, the relevant pressure may be the upstream pressure of fluid flow into the first passageway 130 of the valve body 126 from the fluid pump. When the relevant pressure is at an acceptable or desirable value (or range) , the actuator 160 retains the valve piston 148 in a closed position, not relieving pressure from the fluid pump. If the relevant pressure increases to a certain level or range, the actuator 160 is triggered to move the valve piston 148 to an open position, allowing fluid pressure relief for the fluid pump. After a certain period or, alternately, when the relevant pressure returns to a certain level or range, the actuator 160 of this example is adjusted to allow the valve piston 148 to move back to a closed position, and so on.

Any suitable components and techniques may be used in a pressure-based system. For example, a directional control valve may be used to control fluid power acting upon the actuator piston to allow it to move from an extended position to a retracted position. For example, referring to Figure 3A, the directional control valve is a three-way, two position solenoid valve (not shown) used to control pneumatic or other fluid pressure in the outer portion 172 of the central cavity 170 of the actuator housing 164. The exemplary solenoid valve is connected with the actuator end cap 182 and actuated based upon the relevant pressure of the pressurize device (not shown) . In the embodiment shown, the solenoid valve is maintained in a fluid-to-cylinder/exhaust-blocked position that allows pressurized fluid to the outer portion 172 of the outer cavity 170 through at least one port 166 to act upon the outer side 178 of the actuator piston 174 and move or retain the actuator piston 174 in an extended position. For example, air pressure in the outer portion 172 of the central cavity 170 may, in certain applications, be maintained at approximately 90 psig.

If the relevant pressure reaches a certain value (or range) , the solenoid valve is actuated to move to a supply-fluid-blocked/cylinder-exhausted position, blocking or preventing pressurized fluid from acting upon the outer side 178 of the actuator piston 174 and allowing pressurized fluid from the outer portion 172 of the central cavity 170 to be exhausted from the actuator 160. This permits the actuator piston 174 to move into a retracted position, opening the valve piston 148. When the relevant pressure returns to a desired level or range, the solenoid valve is actuated to allow fluid back into the outer portion 172 of the central cavity 170 of the actuator 160. In the embodiment shown, the mechanical forces on the actuator piston 174 are overcome and the actuator piston 174 returns to an extended position, closing the valve piston 148.

In yet another independent aspect of the invention, the actuator 160 may be electronically controlled by an electronic control device or system, if desired, e.g. the "CONTROLLER" of Figure 2 which may be any suitable control system, computerized system, and/or PLC, on-site or remote. In conjunction with the embodiment of Figure 3A, a control valve in accordance with the present invention is on-site or remotely-operated by a programmable logic controller (PLC) that receives relevant pressure readings from one or more electronic pressure measuring devices (e.g. "SENSOR," Figure 2). For example, the electronic pressure measuring device may be a pressure transducer that accurately measures, detects or reads fluid pressure in the pressurized device or the upstream pressure of fluid within, or proximate to, the first passageway of the valve body. If desired, the electronic pressure measuring device may either continuously or intermittently monitor such pressure. The position of the exemplary remotely-operated directional control valve is varied based upon electrical , mechanical , fluid power or a combination thereof supplied to it based upon at least one reading taken by the electronic pressure measuring device.

In operation of the illustrated embodiment used in conjunction with the valve assembly 100 of Figure 3A, the PLC is powered by any suitable power supply and receives input indicating the relevant pressure from the electronic pressure measuring device. The PLC compares the received fluid pressure value (s) with one or more pre-programmed set point values or ranges (the "set point") . If the relevant pressure reaches the set point, the PLC closes a relay (not shown) , providing electric power to the directional control valve, causing it to function to temporarily block the fluid supply, such as from a rig air source, into the central cavity outer portion and allow the fluid in the outer portion to exhaust out of the actuator through the directional control valve. The actuator piston is then allowed to move into a retracted position, opening the valve piston. Thereafter, when the PLC detects that the relevant pressure has returned to a desired value/range, or based upon some other criteria, the PLC resets, or opens, the relay, reducing or eliminating power to the directional control valve. This causes the valve to function to allow fluid back into the outer portion of the central cavity, which moves the actuator piston back to an extended position. If desired, multiple set points may be used. In one example, a 0-8,000 p.s.i. pressure relief valve assembly 100 snaps open quickly (with minimal throttling) based upon a signal from a pressure transducer at a degree of accuracy of with 20% (±16 psig) of the set point pressure value. However, the present invention is not limited to such electronic control or the control components and techniques described above .

Referring initially to Figure 1 , an embodiment of a pressure relief valve assembly 10 in accordance with the present invention is shown. The pressure relief valve assembly 10 is capable of relieving fluid pressure in a device or system which is desired to be relieved of pressure (referred to herein and throughout this patent as a "pressurized device") . As used herein and throughout this patent, the term "fluid" means one or more gas, liquid, or a combination thereof, and may, if desired and suitable , also include material or particles , or slurries thereof. The pressurized device may, for example, include a triplex or duplex mud pump that may experience overpressure situations. In various embodiments , the valve assemblies of the present invention relieves such overpressure situations. However, the present invention is not limited to such use with mud pumps .

The present invention, therefore, in some, but not necessarily all embodiments, provides pressure relief valve assemblies useful for relieving fluid pressure in a pressurized device, the assemblies having: a valve body with an inlet passageway in fluid communication with an outlet passageway; a valve member within the valve body for selectively controlling fluid flow from the inlet passageway to the outlet passageway, the valve member having a first end and a second end, the outlet passageway having an entrance end and an exit end; the first end of the valve member movable into the outlet passageway to prevent fluid flow from the inlet passageway through the outlet passageway; a wear member around a portion of the entrance end of the outlet passageway; the wear member having an interior surface, the valve member movable within and sealingly contacting the interior surface of the wear member; the outlet passageway having a length, the wear member extending into the outlet passageway a distance less than the length of the outlet passageway; the valve body having an interiorly threaded portion at the entrance of the outlet passageway; the wear member having an exteriorly threaded portion, and the wear member releasably secured to the valve body by threaded engagement of the wear member ' s exteriorly threaded portion with the valve body's interiorly threaded portion. Such assemblies may have one or some (in any possible combination) of the following: wherein the wear member has a length which is less than half the length of the outlet passageway; an actuator connected to the second end of the valve member for selectively actuating the pressure relief valve assembly; the actuator including an actuator housing with a flange, the flange having bolt holes therethrough, the flange releasably bolted to the valve body. ; a first cap at the first end of the valve member, and a second cap at the second end of the valve member; a bore through the valve body, the wear member accessible through the bore for installation and removal thereof; a bore through the valve body, the wear member accessible through the bore for installation and removal thereof, the actuator having an actuator housing bolted to the valve body, part of the actuator housing projecting into the bore, the bore accessible when the actuator housing is unbolted from the valve body and the actuator is removed therefrom; a controller for selectively moving the valve member; the controller includes an automatic reset function to automatically close the pressure relief valve assembly following the pressure relief valve assembly acting to relieve pressure in a pressurized device; the controller programmable to reset at one of a plurality of different measured pressures at the inlet passageway; the controller able to reset the pressure relief valve assembly automatically; the pressure relief valve assembly is resettable manually; the fluid pressure is pressure of drilling fluid and the pressurized device includes apparatus for the flow of drilling fluid under pressure; the pressurized device includes at least one mud pump; wherein the wear member is made of INCONEL material; and/or the actuator is initially acted upon by fluid under pressure to maintain the valve member in a valve-closed position.

The present invention, therefore, provides pressure relief valve assemblies useful for relieving fluid pressure in a pressurized device, the assemblies having: a valve body with an inlet passageway in fluid communication with an outlet passageway; a valve member within the valve body for selectively controlling fluid flow from the inlet passageway to the outlet passageway, the valve member having a first end and a second end, the outlet passageway having an entrance end and an exit end; the first end of the valve member movable into the outlet passageway to prevent fluid flow from the inlet passageway through the outlet passageway; a wear member around a portion of the entrance end of the outlet passageway; the wear member having an interior surface, the valve member movable within and sealingly contacting the interior surface of the wear member; the outlet passageway having a length, the wear member extending into the outlet passageway a distance less than the length of the outlet passageway; the valve body having an interiorly threaded portion at the entrance of the outlet passageway; the wear member having an exteriorly threaded portion; the wear member releasably secured to the valve body by threaded engagement of the wear member ' s exteriorly threaded portion with the valve body's interiorly threaded portion; wherein the wear member has a length which is less than half the length of the outlet passageway; an actuator connected to the second end of the valve member for selectively actuating the pressure relief valve assembly; a bore through the valve body; the wear member accessible through the bore for installation and removal thereof; the actuator having an actuator housing bolted to the valve body, part of the actuator housing projecting into the bore; and the bore accessible when the actuator housing is unbolted from the valve body and the actuator is removed therefrom.

The present invention, therefore, provides in at least some embodiments , but not necessarily all , pressure relief valve assemblies useful for relieving fluid pressure in a pressurized device, the pressure relief valve assemblies having: a valve body with an inlet passageway in fluid communication with an outlet passageway; a valve member within the valve body for selectively controlling fluid flow from the inlet passageway to the outlet passageway, the valve member having a first end and a second end, the outlet passageway having an entrance end and an exit end; the first end of the valve member movable into the outlet passageway to prevent fluid flow from the inlet passageway through the outlet passageway; a wear member around a portion of the entrance end of the outlet passageway; an actuator connected to the second end of the valve member for selectively actuating the pressure relief valve assembly; wherein the actuator includes an actuator housing with a part, e.g., but not limited to, a flange; the part having bolt holes therethrough; and the part and therefore the housing releasably bolted to the valve body. Such an assembly may have: fluid pressure which is pressure of drilling fluid, and the pressurized device including apparatus for the flow of drilling fluid under pressure; and/or the pressurized device including at least one mud pump.

Claims

CLAIMS :

1. A pressure relief valve comprising a body (126) with an inlet passageway (130) and an outlet passageway (140) and a valve member (148,153) for selectively controlling fluid flow from the inlet passageway (130) to the outlet passageway (140) , at least a part of said valve member

(148,153) movable into the outlet passageway (140) to prevent fluid flow from the inlet passageway (130) through the outlet passageway (140) , the pressure relief valve further comprising a wear member (128) around a portion of an entrance end of the outlet passageway

(140) , the body (126) having an interiorly threaded portion at the entrance of the outlet passageway (140) , the wear member (128) having an exteriorly threaded portion, the wear member releasably secured to the body (126) by threaded engagement of the wear member's exteriorly threaded portion with the body's interiorly threaded portion.

2. A pressure relief valve as claimed in Claim 1 , wherein the valve member (148,153) is arranged within the body (126) .

3. A pressure relief valve as claimed in Claim 1 or 2 , wherein the valve member (148,153) has an exterior surface and said wear member (128) has an interior surface, said valve member (148,153) movable within and sealingly contacting the interior surface of the wear member (128) .

4. A pressure relief valve as claimed in any preceding claim, wherein said outlet passageway (140) has a length, the wear member (128) extending into the outlet passageway (140) a distance less than the length of the outlet passageway (140) .

5. A pressure relief valve as claimed in any preceding claim, wherein the wear member (128) has a length which is less than half the length of the outlet passageway (140) .

6. A pressure relief valve as claimed in any preceding claim, further comprising an actuator (160) for selectively moving the valve member (148,153) into the wear member (128) .

7. A pressure relief valve as claimed in Claim 6, wherein the body (126) comprises an opening for receiving a part of the actuator (160) , the opening of sufficient size such that upon removal of the actuator (160) the wear member (128) is accessible therethrough for installation and removal thereof.

8. A pressure relief valve as claimed in Claim 6 or 7 , wherein the actuator (160) comprises an actuator housing

(164) connected to the body (126) .

9. A pressure relief valve as claimed in Claim 8 wherein the actuator housing (164) has a flange, the flange having bolt holes therethrough, the flange releasably bolted to the body (126) .

10. A pressure relief valve as claimed in Claim 7 , 8 or 9, wherein the actuator housing (160) comprises a guide (164) for guiding the valve member (148,153).

11. A pressure relief valve as claimed in Claim 7, 8, 9 or 10, further comprising a valve stem (150) connected to the valve member (148,153).

12. A pressure relief valve as claimed in Claim 11 , wherein the valve stem (150) is fixed to a piston (178) .

13. A pressure relief valve as claimed in Claim 12 , wherein the piston (178) is arranged in a cylinder (166) , and a means for maintaining said valve member (148,153) in a closed position to inhibit flow of fluid from said inlet passageway (130) to said outlet passageway (140) .

14. A pressure relief valve as claimed in Claim 13, wherein said means comprises one of: a pneumatic fluid; a hydraulic fluid; and a combination of pneumatic and hydraulic fluids.

15. A pressure relief valve as claimed in Claim 13 or 14 , wherein said cylinder is provided with a cylinder head (182) .

16. A pressure relief valve as claimed in Claim 13, 14 or 15, wherein said cylinder (166,182) comprises a fluid inlet and outlet port.

17. A pressure relief valve as claimed in any of Claims 11 to 16, wherein the valve member (148,153) has a proximal end connected to the valve stem (150,180) and a cap (139) at said proximal end.

18. A pressure relief valve as claimed in any of Claims 11 to 17, wherein the actuator (160) is provided with a resilient means (184,186) to bias the valve member (148,153) to an open position to allow fluid to flow from the inlet passageway (130) to the outlet passageway (140) .

19. A pressure relief valve as claimed in Claim 18, wherein said resilient means (184,186) comprises at least one spring.

20. A pressure valve as claimed in Claim 18, wherein said resilient means (184,186) comprises at least two nested springs.

21. A pressure relief valve as claimed in any of Claims 11 to 20, further comprising an indicator (156,158) for indicating the position of the valve member (148,153).

22. A pressure relief valve as claimed in Claim 20 , wherein the indicator (156,158) comprises a pin (156) fixed to the valve stem (150,180).

23. A pressure relief valve as claimed in any preceding claim, wherein the valve member (148,153) comprises a cap (153) at the distal end of the valve member (148,153).

24. A pressure relief valve as claimed in any preceding claim, wherein said inlet passageway (130) is arranged substantially at right angles to the outlet passageway (140).

25. A pressure relief valve as claimed in any preceding claim, further comprising a controller for selectively moving the valve member.

26. A pressure relief valve as claimed in Claim 25, wherein the controller includes an automatic reset function to automatically move the valve member to a closed position following the activation of the valve member acting to relieve pressure.

27. A pressure relief valve as claimed in Claim 25, wherein the controller is programmable to reset at least one of a plurality of different measured pressures at the inlet passageway.

28. A pressure relief valve as claimed in Claim 25, 26 or 27, wherein the controller resets the pressure relief valve assembly automatically.

29. A pressure relief valve as claimed in Claim 25, 26, 27 or 28, wherein the pressure relief valve assembly is resettable manually.

30. A pressure relief valve as claimed in any preceding claim, wherein the wear member (128) is made of INCONEL material .

31. A drilling mud apparatus incorporating a pressure relief valve as claimed in any preceding claim.

32. A drilling mud apparatus as claimed in Claim 31 , comprising at least one mud pump.

33. A method for changing a wear member (128) in a pressure relief valve, the pressure relief valve comprising a body (126) having an inlet passageway (130) and an outlet passageway (140) , the wear member (128) arranged at an entrance to the outlet passageway (140) , a valve member (148,153) arranged for selective movement into and from the wear member (128) and an actuator (160) for actuating the valve member (148,153) into and from the wear member (148) to selectively allow and inhibit fluid to be relieved from the inlet passageway (130) to the outlet passageway (140) , the method comprising the steps of removing the actuator (160) from the body (126) to gain access to the wear member (128) .

34. A method in accordance with Claim 33 , wherein the wear member (128) is threaded to the body (126) , the method further comprising the step of unscrewing the wear member (128) from the body (126) .

35. A method for relieving pressure using a pressure relief valve in a system incorporating a mud pump, the pressure relief valve comprising an inlet passageway, an outlet passageway, a valve member and an actuator for actuating the valve member to selectively allow and inhibit fluid to be relieved from the inlet passageway to the outlet passageway, the method comprising the steps of maintaining fluid under pressure in a cylinder of the actuator to maintain the valve member in a closed position to inhibit fluid to pass from an inlet passageway to an outlet passageway and upon pressure rising to a predetermined threshold in said system, relieving the pressure in the cylinder to allow the pressure relief valve to open to allow fluid to be relieved from the inlet passageway to the outlet passageway.

36. A pressure relief valve comprising a body (126) having an inlet passageway (130) , an outlet passageway (140), a valve member (148,153) and an actuator (160) for moving the valve member (148,153) into and from the wear member (148) to selectively allow and inhibit fluid to be relieved from the inlet passageway (130) to the outlet passageway (140), wherein the valve member (148,153) is movable in a direction substantially in line with the flow of fluid through the outlet passageway (140) .

37. A pressure relief valve comprising a body (126) having an inlet passageway (130) , an outlet passageway (140), a valve member (148,153) and an actuator (160) for moving the valve member (148,153) into and from the wear member (148) to selectively allow and inhibit fluid to be relieved from the inlet passageway (130) to the outlet passageway (140) , wherein the outlet passageway (140) is arranged at substantially right angles from the inlet passageway (130) .