| The disk of a Gate valve is completely removed when the valve is fully open; the disk is fully drawn up into the valve Bonnet. Gate valves are general service valves primarily used for on/off, non-throttling service. C). ), ( 3.1 MOV Functional Margin. See Fig. ), ( 38 The bonnet, which containing the moving parts, is attached to the body, usually with bolts, to permit maintenance. I: A hole on the upstream side of wedge to release built-up pressure in bonnet cavity. Pressure binding may not occur if the leakage past the upstream seat is This happens, because the stem is threaded and mated with the bushing threads of a Yoke. 10 Seat ring construction provides seats which are either threaded into position or are pressed into position and seal welded to the valve body. The body is generally connected to other equipment by means of flanged, screwed or welded connections. ), ( It is common practice to use cast iron or ductile iron solid-wedge gate valves in cold or ambient water lines. Sometimes in high-temperature applications, the flow medium, such as water or steam, is trapped in the valve bonnet area when the valve is closed for system shutdown. ), Gate Valve Types, Construction, Applications and Advantages, Post Comments restriction is desired. Ranging of the Gate valves is usually made by the type of wedge used. Gate valves are bidirectional and therefore they can be used in two directions, Pressure loss through the valve is minimal, Gate valves are not suitable for regulate or throttle flow, They are sensitive to vibration in the open state. A hollow wedge is a variation of solid wedge with the exception of a hole in the center. 34 Contact Us Except for NPS 2 (DN 50) and smaller, solid-wedge discs are generally not recommended for use in applications having temperatures in excess of 250 deg F (121 deg C). F: Double-disc non-rising-stem gate valve, Fig. Gate valves are primarily designed to start or stop flow, and when a straight-line flow of fluid and minimum flow restriction are needed. endstream endobj 323 0 obj <>/Metadata 30 0 R/PageLayout/OneColumn/Pages 318 0 R/StructTreeRoot 41 0 R/Type/Catalog>> endobj 324 0 obj <>/ExtGState<>/Font<>/XObject<>>>/Rotate 0/StructParents 0/Type/Page>> endobj 325 0 obj <>stream ), ( A third type of gate valve, called conduit valve, is shown in Fig. 322 0 obj <> endobj 35 ), ( A Unique blog for Oil and Gas Professionals covering topics related to Piping and Process. Gate valves. Gate valves … As the handwheel on the stem is rotated, the disk travels up or down the stem on the threads while the stem remains vertically stationary. The stem is threaded into the disk. The ), ( 0 Motor-Operated Valves Course Manual Theory of MOV Design Basis Operation USNRC Technical Training Center 3-13 05/10 3.2 Design Basis Valve Stem Thrust . ), ( 25 (1) Given a certain differential pressure across the disc, how much thrust (downward force) will be needed to lower the disc to close the valve? The inside diameter of a conduit gate valve is equal to the inside diameter of the connecting pipe. 85 Cast steel wedged gate valve for oil and gas industry, Microbiologically Induced Corrosion (MIC), Differences between Castings and Forgings, Differences between Cast Iron and Cast Steel, Fireproofing for Petrochemical facilities, Standards defined on this website (19 pages), Dimensions Across Flats and Heights of Hex Nuts, Introduction to air-cooled heat exchangers, Image presentation Hot tapping and Line stopping, North Transgas and North European Gas Pipeline (10 Pages). h��V�o�0�W��=t��D�*+[��V Z'U}� �hI���ߝ��x��p�s_�����B$�!� ,����h\�Z� Like the double-disc or parallel-seated gate valve, its disc seats against the downstream seat, depending on the flow direction. In the double-disc parallel-seat valves (Figs. The design of the wastegate body and valve determine the … This type is preferred where the body seats might be distorted due to pipeline strain. A Yoke is an integral part from a Rising Stem valve and is mounted to the Bonnet. H: Pressure binding caused by built-up pressure in bonnet cavity, Fig. ), ( The hollow wedge travels along the stem when the threaded stem is rotated, thus opening or closing the valve port. The valve is responsible for keeping the exhaust gasses out of the gate when it is closed. 79 ), ( Specifically, gate valves are used in applications requiring a straight-line flow of fluid with minimum . Almost all small, NPS 2 (DN 50) and smaller, gate valves are solid-wedge gate valves. 2 However, it is generally preferred because the position of the stem indicates at once whether the valve is open or closed. 47 The major advantage of this type is that the disc cannot be jammed into the body, an action that might make it difficult to open the valve. Some double-disc parallel seat valves employ a design which depends mainly upon the fluid pressure exerted against one side of the disc or the other for its tightness. The wedge is designed to completely stop flow and form a tight seal against pressure in either direction. The following are some of the disadvantages of gate valves that must be considered when selecting a gate valve for an application: Gate valves consist of three major components: Two basic types of gate valves are the manufactured-wedge type and the double-disc type, and there are several variations within each of these types. ), ( 57 19 h�b```��&~�g`f`�s s�ve�\x��/y. This is particularly important where motors are used for opening and closing the valve. 3.0 THEORY OF MOV DESIGN BASIS OPERATION . This type of wedge is suitable for the treatment of non-condensing gases and liquids at normal temperatures, particularly corrosive liquids. adequate to prevent over pressurization of the valve bonnet cavity. In service, these valves generally are either fully open or fully closed. .iW� ڑ���3�֍Ȯ�����#�M���P�$��#�Τx��. Gate valves consists of three main parts: body, bonnet, and trim. Seats for Gate valves are either provided integral with the valve body or in a seat ring type of construction. ;�7�����*��$vT$=u|"��"�2�{*{�G�`GCGD�x 8q� v ��B`� >3�iN�Jڝ�9%����b��`η��A�8i�T���� 338 0 obj <>/Filter/FlateDecode/ID[<60D703B227C74E4AAA5C34E8F1E6FBBD><1188EC1EC15E95468AA88842E2D6A12B>]/Index[322 26]/Info 321 0 R/Length 80/Prev 81216/Root 323 0 R/Size 348/Type/XRef/W[1 2 1]>>stream ), ( Stems are usually forged, and connected to the disk by threaded or other techniques. - Designed by A. Gate Valves. The solid wedge is a single-piece solid construction. E,F and G). In the main Menu "Valves" you will find links to detailed (large) drawings of both stem types. In the open position, the wedge is completely out of the flow stream. There are four types of wedges: solid, hollow, split, and flexible wedge.

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