Description:FIELD OF INVENTION:

[001] The present invention in general relates to Gate valve of forged steel valves for high temperature and low pressure applications. Particularly, the invention relates to a new flexible wedge in Gate valve assembly. More particularly, the invention relates to an operation of gate valve with pneumatic applications.

BACKGROUND OF THE INVENTION:

[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[003] Normally, forged steel gate valves are used in Flue Gas Desulfurization (FGD) plant for water application in thermal power plants. The size of valve ranging from 1/4” to 38” depending upon the pipeline where these valves are used for high temperature and high, medium & low pressure (150, 300, 600, 1500, 2500, 2750, 3000, 3500 and 4000 Class rating) applications. Materials used for the valves are SA105 grade material (carbon steel), F22 grade material (low alloy steel), F91 grade material (high alloy steel), stainless steel and F92 grade material.

[004] Referring to the figure 1, machining of valve body (01) consists of following steps, blind boring is done in the middle of valve body (01). Boring operation is carried out both sides for inlet and outlet correspondingly. Again a step boring operation is done at top of valve body (01) for accommodating the spiral wound gasket (09). Now, four nos of tapped hole are made at the top of valve assembly as shown in figure 1.

[005] Referring to the figure 1, machining of bonnet (04) consists of following steps, the step of both sides top and bottom of bonnet (04) is formed. Step boring in the middle of the bonnet (04) is carried out, thereafter four tapped holes are formed in both of square side & round side flanges of the bonnet (04).

[006] Again referring to the figure 1, machining of stem (03) consists of following steps, a round rod is taken for stem (03) machining, wherein threading operation is carried out in one side and step milling operation is carried out in the another side as shown in figure.

[007] Reference may be made to figure 2, machining of solid wedge (05) consists of following steps, a solid wedge in forged form is received as input material. Both surfaces of solid wedge (05) are ground well by surface grinding machine to required surface finish.

[008] In valve assembly, lapping operation is carried out in the solid wedge (05) for required finish (0.8µ). Set of Seat rings (07) are fitted into the valve body (01) both inlet and outlet. Now, Blue matching inspection is conducted between the solid wedge (05) with seat ring (07). If mis-matching is found in the inspection, it leads to valve leakage during the hydro testing. Hence, it is required to extend the lapping time substantially. After completion of blue matching inspection, the solid wedge (05) is inserted into a step provided in the stem (03) then assembled with valve body (01). A spiral wound gasket is inserted in the valve body (01) to take care of shell leakage. The bonnet (04) is assembled over the valve body (01) by fastening the four allen bolts (02). After that, a packing cartridges (08) are inserted in between bonnet (04) and stem (03) followed by gland follower (10) and gland flange (11) assembly. Then, the Actuator (12) is mounted at the top of bonnet (04) and fastened with four bolts (06). Now, the actuator (12) and valve body (01) are connected properly and witnessed by checking the valve operations manually.

[009] Thereafter, valve assembly is moved to hydro testing station. ‘Hydro testing’ is an important process where the customer witnesses each product whether it meets all quality requirements or not. In hydro testing station, three type of tests are being conducted, one is seat test which is tested in fully closed condition of valve assembly, second one is backseat test which is tested in fully opened condition of valve assembly and third one is shell test which is tested in partially opened condition of valve assembly. While hydro testing of valve, seat leakage is observed. So, valve assembly is dismantled for rectifying the problems.

[0010] In existing method, normally solid wedges are having low flexibility in matching with the corresponding seat rings in valve body (01). Apart from that the actuator used to operate the valve needs high thrust force, so that high torque actuators are preferred obviously. This also leads to increase in the cost of actuator. Hence, there has been a need to design a new method for valve assembly faster and also these problems are to be addressed while developing a method of gate valve assembly for the above applications.

PRIOR ART:

[0011] Now, reference may be made to the following:
[0012] CN202646749U: It relates to a high-temperature high-pressure large-diameter overall forging wedged gate valve. The forging wedged gate valve comprises a valve body, a valve seat, a gate plate, a valve rod, a valve cover, a support, a transmission mechanism, a sealing piece and a mounting piece, wherein the gate plate is of a wedged structure; the valve body serves as a forge piece; a valve body inlet channel, a valve body outlet channel and a valve body middle channel form an overall structure; the middle channel adopts a pressure self-sealing structure; the pressure self-sealing structure consists of a valve cover, a sealing ring and a clamping ring; the lower end surface of the valve cover is arranged on a step of the middle channel of the valve body in a pressing way; an outer conical surface is arranged on the valve cover; an inner conical surface matched with the outer conical surface of the valve cover is arranged on the sealing ring; and the upper end surface of the sealing ring is arranged between the valve body and the valve cover by the clamping ring in the pressing way. The forging wedged gate valve has the advantages of high temperature resistance, high pressure resistance, reliable sealing performance, low manufacturing cost and the like, and is easy to manufacture and suitable for being used on heavy-caliber medium pipelines.

Differences with respect to CN202646749U:

[0013] The purpose of this utility model is the deficiency that exists for prior art, provides a kind of high temperature resistant, high pressure resistant, sealability reliable, easy processing, low cost of manufacture, is applicable to the High Temperature High Pressure major diameter solid forging wedge action valve of large diameter pipeline operating mode.

[0014] The technical solution of the utility model comprises valve body, valve seat, flashboard, valve rod, valve gap, support, driving mechanism, Sealing and assembling set, flashboard is wedge-shaped structure, valve seat has the wedge-type seal face that cooperatively interacts with flashboard, and valve body is shaped with inlet passage, outlet passage and Zhong Dao; Mainly be that valve body is forging, valve body inlet passage, outlet passage and middle road are overall structure; Middle road adopts the pressure self-sealing structure, this pressure self-sealing structure is comprised of valve gap, seal ring, snap ring, the valve gap lower end surface is fitted on the step in road in the valve body, valve gap is shaped with outer conical surface, seal ring is shaped with the internal conical surface that cooperatively interacts with the valve gap outer conical surface, and the seal ring upper-end surface is fitted between valve body and the valve gap by snap ring.

[0015] In above technological scheme, seal ring adopts stainless steel material, difference pile-up welding hard alloy material between seal ring and valve gap and the valvebody surface of contact.

[0016] The above technological scheme, is shaped with sealing surface in the middle of the valve gap lower end surface, sealing surface and the flashboard upper-end surface formation sealing pair that cooperatively interacts on this.

[0017] The above technological scheme adopts the reversed V-shape stuffing seal between valve rod and the valve gap.

US6338469B1

[0018] A wedge gate valve having a valve body defining a valve chamber and flow passages and upwardly diverging circular seat surfaces of circular, flat configuration and defining seat planes. A valve disk or wedge having downwardly converging sealing surfaces is movable within said valve chamber between open and closed positions for controlling flow through the valve. Pressure boundary plates connected by hubs to the valve disk define the sealing surfaces of the disk and have bottom corners that establish line contact with the downstream seat surface and prevent any portion of said sealing surfaces of said valve disk from crossing the sealing plane of the downstream seat in the event of flow responsive downstream movement of the valve disk during its opening and closing movement. Guide ears of the disk are provided with flexible upper and lower extremities and rounded or chamfered inner end surfaces to minimize localized peak contact stress with disk guide rails of the valve body. The center section of the disk is rendered flexible by the provision of an internal transverse cavity that extends completely through the center section or is located centrally of the center section to define flexible walls between the hubs to thus provide for disk flexibility for overcoming the tendency for disk binding. A valve actuator for opening and closing the valve disk is provided with an adjustable down stop to prevent overtravel of the disk during seating.

[0019] None of the known arts can fulfil the requirements, for which the present invention has been devised.

OBJECTS OF THE INVENTION:

[0020] It is therefore, an object of the invention to propose a new type gate valve with a flexible wedge in valve assembly for low pressure applications.

[0021] One more object of the invention is to provide a method for manufacturing of pneumatic forged steel gate valve with flexible wedge for high temperature and low pressure applications in thermal power plants.

[0022] Another objective of the present invention is to provide a novel wedge gate valve which prevents damage to guide and sealing surfaces even when the valve is subjected to worst case pressure and flow operating conditions, and which overcomes the typical pinching, thermal binding, and over-travel/over-thrust problems encountered with conventional wedge gate valves.

[0023] One another object of the invention is to propose a pneumatic actuator for valve operations without electric power.

[0024] Yet further object of the invention is to propose a leak free arrangements in gate valve.

[0025] Still further object of the invention is to avoid rework rate in valve manufacturing.
[0026] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION:

[0027] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.

[0028] In existing method, the solid wedge type gate valve is most commonly used type of gate valve. The wedge is a single piece construction machined to match with the valve body seat in order to provide a tight sealing action. The disadvantage of said solid wedge is that it is prone to getting locked in position if there is a slight deformation in the valve body due to thermal expansion or bending loads. The flexible wedge gate valve overcomes this limitation.

[0029] The present invention discloses a development of flexible wedge arrangement in forged steel gate valves with pneumatic actuator in high temperature and low pressure applications. In the present disclosure a flexible wedge is used in forged steel gate valves instead of solid wedge, wherein the said flexible wedge having annular groove which allows the wedge to flex within the body seat, moreover flexible wedge can accommodate deformation in the valve body.

[0030] According to the present invention, there is provided a method for manufacturing of forged steel gate valve with flexible wedge comprising the steps of:
- Machining of valve body (01);
- Machining of bonnet (04);
- Machining of stem (03);
- Machining of flexible wedge (13);
- Valve assembly, which involves the following steps:
lapping operation is carried out in the flexible wedge (13) for required finish (0.8µ), Set of Seat rings (07) are fitted into the valve body (01) both inlet and outlet, Blue matching inspection is conducted between the flexible wedge (13) with seat ring (07); If mis-matching is found in the inspection, it leads to valve leakage during the hydro testing. Hence, it is required to extend the lapping time substantially. After completion of blue matching inspection, the flexible wedge (13) is inserted into a step provided in the stem (03) followed by assembling with the valve body (01);

- A spiral wound gasket is inserted in the valve body (01), the bonnet (04) is assembled over the valve body (01) by fastening; a packing cartridges (08) are inserted between bonnet (04) and stem (03) followed by gland follower (10) and gland flange (11) assembly;

- an actuator (12) is mounted at the top of bonnet (04) and fastened, in which the actuator (12) and valve body (01) are connected and witnessed by checking the valve operations.

[0031] Then, valve assembly is moved to hydro testing station. While hydro testing of valve, it is found there is no seat leakage.

[0032] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

[0033] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

[0034] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0035] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:

Figure 1 shows: Pneumatic gate valve assembly with solid wedge in prior art.
Figure 2 shows: Solid wedge according to the prior art.
Figure 3 shows: Pneumatic gate valve assembly with flexible wedge in accordance with the present invention.
Figure 4 shows: Flexible wedge of the present invention.

[0036] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:

[0037] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

[0038] The present invention makes a disclosure regarding an invention directing to a method for manufacturing of pneumatic forged steel gate valve with flexible wedge for high temperature and low pressure applications in thermal power plants.

[0039] Referring to the figure 3, machining of valve body (01) comprises of following steps, blind boring is done in the middle of valve body (01). Boring operation is carried out both sides for inlet and outlet correspondingly. Again a step boring operation is done at top of valve body (01) for accommodating the spiral wound gasket (09). In the same position, Slotting operation is performed at the middle of the valve body (01) to move Flexible wedge (13) smoothly. Now, four nos of tapped hole is made at the top of valve assembly as shown in figure.

[0040] Referring to the figure 3, machining of bonnet (04) comprises of following steps, the steps of both sides top and bottom of bonnet (04) is formed. Step boring in the middle of the bonnet (04) is carried out then four tapped holes are formed in the both of square side & round side flanges of the bonnet (04).

[0041] Referring to the figure 3, machining of stem (03) comprises of following steps, a round rod is taken for stem (03) machining, threading operation is carried out in one side and step milling operation is carried out in the another side as shown in figure.

[0042] Referring to the figure 4, machining of flexible wedge (13) comprises of following steps, a solid wedge (05) in forged form is received as input material. A groove is provided in peripherally towards to centre of wedge as shown in figure. Now, solid wedge (05) is converted into flexible wedge (13). Both surfaces of flexible wedge (13) are ground well by surface grinding machine to required surface finish.

[0043] In valve assembly, lapping operation is carried out in the flexible wedge (13) for required finish (0.8µ). Set of Seat rings (07) are fitted into the valve body (01) both inlet and outlet. Now, Blue matching inspection is conducted between the flexible wedge (13) with seat ring (07). If mis-matching is found in the inspection, it leads to valve leakage during the hydro testing. Hence, it is required to extend the lapping time substantially. After completion of blue matching inspection, the flexible wedge (13) is inserted into a step provided in the stem (03) then assembled with valve body (01). A spiral wound gasket is inserted in the valve body (01). The bonnet (04) is assembled over the valve body (01) by fastening the four allen bolts (02). After that, a packing cartridges (08) are inserted in between bonnet (04) and stem (03) followed by gland follower (10) and gland flange (11) assembly. Then the Actuator (12) is mounted at the top of bonnet (04) and fastened with four bolts (06). Now, the actuator (12) and valve body (01) are connected properly and witnessed by checking the valve operations manually.

[0044] Then, valve assembly is moved to hydro testing station. While hydro testing of valve, it is found that no seat leakage. So, valve assembly is found okay. Thereby, cycle time of valve and operator fatigue reduced drastically, safety improved and substantial savings in time and money.

[0045] One of the features of the present invention is to provide a novel flexible wedge gate valve wherein the damage potential at the disk guide slot to body guide rail interface is eliminated by providing novel guide ear elements having flexible cantilever guide end sections which flex elastically and have contoured leading edges, and which serves to minimize localized peak contact stress at the interface with the guide rails of the valve body.

[0046] Another feature of the present invention is to provide a flexible wedge disk having much higher flexibility than conventional wedge gate valve designs by incorporation of a novel flexible member interposed between and being integral with opposed pressure boundary plates which provides control of disk flexibility independently of pressure boundary plate thickness, and provides the required disk flexibility without violating Code stress limits.

[0047] Another important feature of the present invention is a straight edge at the lower end of the disk faces which greatly increases the contact area between the disk and seat faces at the first instance of contact when closing, and at the last instance of contact when opening, thereby minimizing contact stress and preventing the gouging action common to prior art designs. The straight lower edge is contoured to further minimize peak contact stress.

[0048] It is also a feature of the present invention to incorporate an adjustable stem stop to limit the contact force between the disk and seat faces to a desirable range by preventing over-wedging. Over-wedging can result from a combination of inertia effects and a tendency for the stem and disk friction encountered in actual operation to be significantly lower than the conservative design values used for determining motor operator torque switch trip settings.

[0049] Throughout much of the opening and closing movement of the disk, the differential pressure load across the disk is transmitted to the body guide rails by disk guide ear elements which define guide slots on opposite sides of the disk. In the present invention the upper and lower ends of the guide ear elements incorporate flexible cantilever guide ends which, compared to the prior art, significantly reduce the peak contact stress between the body guides and the disk guide ear elements. The leading edge geometry of the flexible cantilever guide ends are provided with a transitional contour (such as a radius or chamfer) instead of the usual sharp edge to further reduce peak contact stress. The length and profile of the flexible cantilever guide ends control the flexibility thereof. The profile of the flexible cantilever guide ends can be uniform in thickness or can be provided with a taper to achieve greater flexibility. By suitable design of the length, profile and leading edge contour of the flexible cantilever guide ends, the localized guide interface peak contact stress is dramatically minimized in comparison with conventional wedge gate valve designs. In the preferred embodiment, the cantilever flexible guide ends are created by the incorporation of relief slots between the guide ear elements and the disk flexible center section.

[0050] To limit the depth of seating movement of the flexible disk member and to limit the seating force of the disk against the fixed seats of the valve body, an adjustable stem stop is provided on the threaded valve stem of the preferred embodiment of this invention. This stem stop prevents over-wedging which could otherwise occur due to unpredictably low values of stem thread and disk friction and high inertia effects.

ADVANTAGES:

[0051] The present invention overcomes typical thermal binding problems while providing the advantage of a high sealing reliability in both low pressure and high pressure conditions by employing a unique geometry of a one-piece flexible wedge design in which the desired wedge flexibility can be independently achieved while maximum stresses in the disk are kept within the allowable limits, e.g., ASME Section III Boiler and Pressure Vessel Code limits. Unlike the conventional flexible wedge gate design, the disk configuration of this invention is provided with a center section between the two pressure boundary plates which incorporates flexible walls to provide the required disk flexibility without interfering with the Code stress limits.

[0052] Due to low flexibility of solid wedge compared to flexible wedge, slightly excess torque.
[0053] Actuator is required in operation. Hence, low torque actuator is sufficient in valve operations thereby it reduces the valve cost.

[0054] The present invention increases the productivity and utilizes lot of resources in better way. It simplifies the existing methods and cycle time of valve is reduced substantially.
[0055] Thus, the drawbacks in the background of the invention are totally eliminated which leads to productivity by reduction of cycle time in the manufacturing.

WORKING OF THE INVENTION:

[0056] In this invention, Pneumatic valve with a new novel flexible wedge is needed only low torque in operations, thus results to opt low torque actuators so that cost benefited with this design.

TEST RESULT

[0057] Particularly during Air leak test, Pressure drop is within the permissible range. So, customers are satisfied. Which is difficult in the previous design.

[0058] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

[0059] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[0060] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

[0061] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

[0062] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0063] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

[0064] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

REFERENCE NUMERALS

01 VALVE BODY
02 ALLEN BOLT
03 STEM
04 BONNET
05 SOLID WEDGE
06 BOLTS
07 SEAT RING
08 PACKING CARTRIDGES
09 SPIRAL WOUND GASKET
10 GLAND FOLLOWER
11 GLAND FLANGE
12 ACTUATOR
13 FLEXIBLE WEDGE
, Claims:WE CLAIM:

1. A method for manufacturing of forged steel gate valve with flexible wedge comprising the steps of:
- machining of valve body (01);
- machining of bonnet (04);
- machining of stem (03);
- machining of flexible wedge (13);
- valve assembly, which involves the following steps:
lapping operation is carried out in the flexible wedge (13) for required finish (0.8µ), Set of Seat rings (07) are fitted into the valve body (01) both inlet and outlet, Blue matching inspection is conducted between the flexible wedge (13) with seat ring (07), wherein the flexible wedge (13) is inserted into a step provided in the stem (03) followed by assembling with the valve body (01);
- a spiral wound gasket is inserted in the valve body (01), the bonnet (04) is assembled over the valve body (01) by fastening; a packing cartridges (08) are inserted between bonnet (04) and stem (03) followed by gland follower (10) and gland flange (11) assembly;
- an actuator (12) is mounted at the top of bonnet (04) and fastened, in which the actuator (12) and valve body (01) are connected and witnessed by checking the valve operations.

2. The method as claimed in claim 1, wherein the Machining of valve body (01) involves following steps:
blind boring is done in the middle of valve body (01), boring operation is carried out both sides for inlet and outlet correspondingly, wherein a step boring operation is done at top of valve body (01) for accommodating the spiral wound gasket (09), and
in the same position, Slotting operation is performed at the middle of the valve body (01) to move Flexible wedge (13) smoothly, in which plurality of tapped holes are provided at the top of valve assembly (05).
3. The method as claimed in claim 1, wherein the Machining of bonnet (04) involves following steps:
both sides top and bottom of bonnet (04) is formed, step boring in the middle of the bonnet (04) is carried out and multiple tapped holes are formed in the both of square side and round side flanges of the bonnet (04).

4. The method as claimed in claim 1, wherein the Machining of stem (03) comprises of following steps:
a round rod is taken for stem (03) machining, wherein threading operation is carried out in one side and step milling operation is carried out in the another side.

5. The method as claimed in claim 1, wherein the Machining of flexible wedge (13) comprises of following steps:
a solid wedge (05) in forged form is received as input material and a groove is provided in periphery towards centre of wedge, wherein the solid wedge (05) is converted into flexible wedge (13), and both surfaces of flexible wedge (13) are ground by surface grinding machine to required surface finish.

6. The method as claimed in claim 1, wherein the bonnet (04) is assembled over the valve body (01) by fastening multitude of allen bolts (02) and said actuator (12) is mounted at the top of bonnet (04) and fastened with multiple bolts (06).

7. The method as claimed in claims 1-6, wherein the flexible wedge gate valve is provided, in which the damage potential at the disk guide slot to body guide rail interface is eliminated by providing guide ear elements having flexible cantilever guide end sections which flex elastically and have contoured leading edges, and which serves to minimize localized peak contact stress at the interface with the guide rails of the valve body.

8. The method as claimed in claims 1-7, wherein a flexible wedge disk is provided by incorporation of a flexible member interposed between and being integral with opposed pressure boundary plates which provides control of disk flexibility independently of pressure boundary plate thickness, and provides the required disk flexibility without violating Code stress limits.

9. The method as claimed in claims 1-8, wherein a straight edge at the lower end of the disk faces is provided which increases the contact area between the disk and seat faces at the first instance of contact when closing, and at the last instance of contact when opening, thereby minimizing contact stress and preventing the gouging action.

10. The method as claimed in claims 1-9, wherein an adjustable stem stop is incorporated to limit the contact force between the disk and seat faces to a desirable range by preventing over-wedging.