Claims:WE CLAIM:
1. A method for manufacturing high pressure and high temperature drain valve assembly, the method comprises steps of:
performing step turning operation in a modified seat ring 9 to accommodate a ring 10;
assembling the ring 10 on the modified seat ring 9 by performing tungsten inert gas welding to produce seat ring assembly;
machining a modified valve body 8 by performing boring operation at the center of the modified valve body 8, turning operation at outer surface of the bottom side of the modified valve body 8 and step boring at outlet of modified valve body 8;
performing top facing operation at the opposite side of the modified valve body 8;
performing step boring operation in the middle of the modified valve body 8 for fixing the new seat ring assembly and a step is machined at the top side to accommodate a spiral wound gasket;
machining the modified valve body 8 for inlet and four threaded holes are made at the top surface for mounting a yoke assembly;
fixing the seat ring assembly in the middle of the modified valve body 8 to produce valve body assembly;
preheating valve body assembly in the heat treatment shop;
performing welding operation to weld seat ring assembly on the valve body 8 by manual arc welding;
post-heating the welded valve body assembly;
performing visual examination and liquid penetration inspection for testing the valve body assembly for potential leakage;
performing lapping operation on the valve body assembly and stem 7 for desired surface finish;
mounting yoke assembly on four threaded holes machined on top surface of the modified valve body 8 to complete high pressure and high temperature drain valve assembly; and
performing hydro tests on the high pressure and high temperature drain valve assembly for potential leakage.
2. The method as claimed in claim 1, wherein material of the ring 10 is same as modified valve body 8.
3. The method as claimed in claim 1, wherein material used to make the assembly includes F91 grade material, F22 grade material and carbon steel.
4. The method as claimed in claim 1, wherein preheating of valve body assembly is done at 215oC -225oC for F91 grade material, 195 oC-205oC for F22 grade material.
5. The method as claimed in claim 1, wherein post heating of valve body assembly is done at 750oC- 770 oC for F91 grade material, 700 oC-750 oC for F22 grade material.
6. The method as claimed in claim 1, wherein pre heating and post heating is not needed for carbon steel body.
7. The method as claimed in claim 1, wherein material of electrode used in manual arc welding to weld seat ring assembly on the modified valve body 8 is same as modified valve body 8 material.
8. The method as claimed in claim 1, wherein yoke assembly is mounted on the modified valve body 8 by means of screwing the stud and nut.
9. A high pressure and high temperature drain valve assembly, the assembly comprises:
a seat ring assembly having a ring 10 welded on a modified seat ring 9, wherein the ring 10 is welded on a modified seat ring 9 at a step machined to accommodate the ring 10;
a valve body assembly having the seat ring assembly fixed in the middle of a modified valve body 8, an actuator 5 and a spiral wound gasket fitted at a step machined at the top side of the modified valve body 8; and
a yoke assembly having a stem 7, a gland follower 4 and a gland flange 6 mounted on the valve body assembly by means of stud and nut.

10. The drain valve assembly as claimed in claim 9, wherein the ring 10 is welded on the modified seat ring 9 by means of Tungsten Inert Gas (TIG).

11. The drain valve assembly as claimed in claim 9, wherein boring operation is performed at the center of the modified valve body 8 and turning operation is performed at outer surface of the bottom side of the modified valve body 8.

12. The drain valve assembly as claimed in claim 9, wherein an inlet and four threaded holes are machined at the top surface for mounting the yoke assembly.

13. The drain valve assembly as claimed in claim 9, wherein the seat ring assembly is fixed in the middle of the modified valve body 8 by manual arc welding.
, Description:[001] The present invention generally relates to manufacturing of drain valves for high temperature and high pressure applications. Particularly, the invention relates to manufacturing of drain valve for high pressure steam turbines. More particularly the invention relates to an improved drain valve having modified valve body. Still more particularly the invention relates to having modified seat ring and new ring in one assembly.
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, the drain valve is used in turbine extraction lines where high pressure drop is involved and also used on any throttling service which results in severe erosion and rapid wearing out of conventional design valves in the drain applications. The size of valve ranging from 25/40 to 40/80 depends upon the pipeline where these valves are used for high temperature and high pressure (1500, 2500, 3000 and 3500 Class rating) applications. Materials used for the valves are SA105 grade material (carbon steel), F22 grade material (low alloy steel) and F91 grade material (alloy steel).
[004] Referring to the figure 1, machining of the valve body (01) consists of the following steps, through drilling and boring operation is done at the center axis of the valve body (01) then turning operation is carried out at outer surface of bottom side. In the same position, step boring is carried out at the outlet of valve body (01). By holding the opposite side of valve body (01) in the machine, top facing operation is carried out followed by step boring operation for fixing the seat ring (02) in the body of the valve. Then valve body (01) is machined for inlet then four threaded holes are made at the top surface for mounting the yoke assembly. Seat ring (02) made up of stellite is fixed in the step created by boring of the valve body (01).
[005] After that valve body assembly is moved for carrying the welding process. Before doing the welding of valve body is pre heated in the furnace, where pre heating is done at 220 degree celsius for F91 grade material, 200 degrees Celsius for F22 grade material, whereas carbon steel bodies are not required to pre heat. After pre heating, valve body assembly is moved to the welding shop where the valve body (01) is welded with seat ring (02) by means of manual arc welding process. Inconel electrode is preferred for welding this assembly. Because inconel has the high ability to weld the hard material (stellite) with soft material. After completion of welding process, valve body assembly is post heated at 750 to 770 degree Celsius for F91 grade material, 700 to 750 degree celsius for F22 grade material, whereas carbon steel bodies do not require post weld heat treatment. The welding process is very stringent for F91 grade materials because of pre-heat, post heat and stress relieving requirements. After the heat treatment is over, the assembly is taken out for both visual examination and Liquid Penetration Inspection (LPI). If the test is found okay, the other components are assembled.
[006] In assembly, lapping operation is carried out in the valve body assembly as well as stem (07) for desired surface finish. After that, yoke assembly is done with necessary components. Then, yoke assembly is mounted with the valve body assembly and tightened by means of screwing the stud and nut. Then the valve assembly is moved to hydro testing.
[007] While hydro testing of valve, it is found that seat leakage and ring leakage. So, valve assembly is dismantled for rectifying the problems. These leakages are occurred due to seat crack and welding crack. Again, valve body (01) is sent back to machining for removing the seat ring (02) from the valve body (01) and seat ring (02) is thrown to scrap which leads to heavy loss of material (because of raw stellite). Again new seat ring (02) is fixed at the same place and same procedure is repeated in the heat treatment, welding, machining, assembly and hydro testing stations. Time taken to complete this cycle is approximately one week per valve/lot. This leads to more lead time for the delivery and also leads more fatigue to the operator as well as wastage of costly resources.
[008] Hence, there is a need to improve the valve design. These problems are to be addressed while designing the drain valve for the above applications.
[009] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Object of the Invention
[010] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior method and valves.
[011] Another object of the invention is to propose a high pressure and high temperature modified drain valve assembly.
[012] Another object of the invention is to propose a new ring to be used as an intermediate component between the valve of body and seat ring.
[013] Yet another object of the invention is to propose a high pressure and high temperature modified drain valve assembly which reduces the process cost.
[014] Yet another object of the invention is to propose a high pressure and high temperature modified drain valve assembly which increase productivity by reducing the rework and rejection rate.
[015] Yet another object of the invention is to propose a new method of welding for joining the valve body and seat ring.
[016] Still yet another object of the present invention is to propose a high pressure and high temperature drain valve assembly to eliminate seat leakage due to seat crack.
[017] Still yet another object of the present invention is to propose a high pressure and high temperature drain valve assembly to eliminate ring leakage due to welding crack.
[018] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
Summary of the Invention
[019] One or more drawbacks of conventional valve, and additional advantages are provided through the 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 a part of the claimed disclosure.
[020] Accordingly, as shown in the figure 2, a ring is made with suitable dimensions as to fit with the modified seat ring (09). Material selected for ring is same as the body material. A step turning is carried out in the seat ring to accommodate the ring. After that, the ring and seat ring are fitted, then welded by means of Tungsten Inert Gas (TIG).
[021] The valve body machining consists of the following steps, boring operation is done at the center of the valve body then turning operation is carried out at outer surface of bottom side. In the same position, step boring is carried out at outlet of valve body. By holding the opposite side of valve body in the machine, top facing operation is done. Then step boring operation is carried out for fixing the new seat ring assembly in the middle of the valve body and a step is machined at the top side to accommodate the spiral wound gasket. Then valve body is machined for inlet then four threaded holes are made at the top surface for mounting the yoke assembly. New seat ring assembly is fixed in the middle of the valve body.
[022] After that valve body assembly is moved to the heat treatment shop for pre heating by furnace where pre heating is done at 220 degrees Celsius for F91 grade material, 200 degrees Celsius for F22 grade material whereas carbon steel bodies are not required to pre heat. After pre heating, valve body assembly is moved to the welding shop where the modified valve body (08) is welded with new seat ring assembly by means of manual arc welding process. Material of electrode is usually same as body material. Again valve body assembly is post heated at 750 to 770 degree Celsius for F91 grade material, 700 to 750 degree Celsius for F22 grade material whereas carbon steel bodies are not required to post heat. After the heat treatment is over, the assembly is taken out for both visual examination as well as and Liquid Penetration Inspection (LPI). If the test is found okay, the other components are assembled.
[023] A high pressure and high temperature drain valve assembly, the assembly comprises: a seat ring assembly having a ring 10 welded on a modified seat ring 9, wherein the ring 10 is welded on a modified seat ring 9 at a step machined to accommodate the ring 10; a valve body assembly having the seat ring assembly fixed in the middle of a modified valve body 8, an actuator 5 and a spiral wound gasket fitted at a step machined at the top side of the modified valve body 8; and a yoke assembly having a stem 7, a gland follower 4 and a gland flange 6 mounted on the valve body assembly by means of stud and nut.
[024] In assembly, lapping operation is carried out in the valve body assembly as well as stem for desired surface finish. After that, yoke assembly is done with necessary components. Then, yoke assembly is mounted with the valve body assembly and tightened by means of screwing the stud and nut. Then the valve assembly is moved to hydro testing.
[025] While hydro testing, it is found that no leakage occurred in the improved drain valve and valve is completed with final inspection. By means of the above assembly, the modified seat ring assembly having no defect found at seat area as well as welded area. Hence, seat leakage due to seat crack and ring leakage due to welding crack is completely eliminated by this improved method. Moreover, material of electrode required for welding the seat ring and valve body is now changed to alloy steel instead of inconel. This not only reduces the process cost, but also increases productivity by reducing the rework and rejection rate. Time taken to complete valve is now approximately three days per valve/lot instead of one week per valve/lot in the existing method.
[026] Now, this modified method of manufacturing of forged high pressure drain valve leads to increase the productivity to two times more than existing method of manufacturing of drain valve.
Brief description of the accompanying drawings.
[027] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[028] Figure 1 shows the sectional view of existing valve assembly with all the part assembled;
[029] Figure 2 shows the sectional view of valve assembly with all the part assembled;
[030] Figure 3 shows the sectional views of assembly of seat ring with new ring, this assembly is made as one component;
[031] Figure 4 shows the sectional view of valve assembly consists of valve body, seat ring along with ring;
[032] Figure 5A and 5B shows the flow diagram of the method as disclosed in the present invention.
[033] Figure 6 shows the comparison of sectional view of existing seat ring with new seat ring;
[034] Figure 7 shows the comparison of sectional view of existing valve body assembly with new valve body assembly;
The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily 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
[035] 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.
[036] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[037] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[038] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[039] Accordingly, as shown in the figure 2, a ring (10) is made with suitable dimensions as to fit with the modified seat ring (09) (refer figure-6). Material selected for ring is same as the body material. A step turning is carried out in the modified seat ring (09) to accommodate the ring (10). After that, the ring (10) and modified seat ring (09) are fitted, then welded by means of Tungsten Inert Gas (TIG).
[040] The modified valve body (08) (refer figure-7) machining consists of the following steps, boring operation is done at the center of the modified valve body (08) then turning operation is carried out at outer surface of bottom side. In the same position, step boring is carried out at outlet of modified valve body (08). By holding the opposite side of modified valve body (08) in the machine, top facing operation is done. Then step boring operation is carried out for fixing the new seat ring assembly in the middle of the modified valve body (08) and a step is machined at the top side to accommodate the spiral wound gasket. Then the modified valve body (08) is machined for inlet then four threaded holes are made at the top surface for mounting the yoke assembly. New seat ring assembly is fixed in the middle of the modified valve body (08).
[041] After that valve body assembly is moved to the heat treatment shop for pre heating by furnace where pre heating is done at 220 degree Celsius for F91 grade material, 200 degree Celsius for F22 grade material whereas carbon steel bodies are not required to pre heat. After pre heating, valve body assembly is moved to the welding shop where the modified valve body (08) is welded with new seat ring assembly by means of manual arc welding process. Material of electrode is usually same as body material. Again valve body assembly is post heated at 750 to 770 degree Celsius for F91 grade material, 700 to 750 degree Celsius for F22 grade material whereas carbon steel bodies are not required to post heat. After the heat treatment is over, the assembly is taken out for both visual examination as well as and Liquid Penetration Inspection (LPI). If the test is found okay, the other components are assembled.
[042] A high pressure and high temperature drain valve assembly according to the present invention comprises: a seat ring assembly having a ring 10 welded on a modified seat ring 9, wherein the ring 10 is welded on a modified seat ring 9 at a step machined to accommodate the ring 10; a valve body assembly having the seat ring assembly fixed in the middle of a modified valve body 8, an actuator 5 and a spiral wound gasket fitted at a step machined at the top side of the modified valve body 8; and a yoke assembly having a stem 7, a gland follower 4 and a gland flange 6 mounted on the valve body assembly by means of stud and nut.
[043] In assembly, lapping operation is carried out in the valve body assembly as well as stem (07) for desired surface finish. After that, yoke assembly is done with necessary components. Then, yoke assembly is mounted with the valve body assembly and tightened by means of screwing the stud and nut. Then the valve assembly is moved to hydro testing.
[044] While hydro testing, it is found that no leakage occurred in the improved drain valve and valve is completed with final inspection. By means of the above assembly, the seat ring assembly having no defect found at seat area as well as welded area. Hence, seat leakage due to seat crack and ring leakage due to welding crack is completely eliminated by this improved method. Moreover, material of electrode required for welding the seat ring and valve body is now changed to alloy steel instead of Inconel. This not only reduces the process cost, but also increases productivity by reducing the rework and rejection rate. Time taken to complete valve is now approximately three days per valve/lot instead of one week per valve/lot in the existing method.
[045] Now, this modified method of manufacturing of forged high pressure drain valve leads to increase the productivity to two times more than existing method of manufacturing of drain valve.
[046] 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 particular 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 analogous 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.”
[047] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[048] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.