Solid-wedge gate valves are generally used in moderate to lower pressure-temperature applications. �hX��D�ф�D�z5��*�!$�{쨔S���5ph�C����sڻJɏlQ�?�׫�2[�A����ܶ����4�z��t�U?�����e�����SZguN'��[�����_M�&�E���缘�k�uD?��L0C��lVF:\�u��z~8S*�61�l�Gkf�b��n\,�\���j����:[*����oӳ�j1��=�7y=��BQu� 2�ѫ:[�^9[�ѴΗ_�]�)}�X׫ ��V"��ub������d5-��/�^Y�{Xl�z0�6pd�;pM�K�zDJ���{�x�p�G����z0&&�R"C-QJW����������:��0�+�]�[����'��;�Ʈn�9� E�X_ܣ-��f}�����R���&AQ*�� ��5���v�{g�1 T6�m��D���U��Qwa�d�bKR��0�K�8�� C�v2���:F�i�f�:[�db��5�@�Y�o�ڊ D: Valve – Inside of the body is the valve. 19 C). B: Rising-stem solid-wedge gate valve for 250-psig steam service, Fig. Gate valves … It is also referred to as a slide valve or parallel slide. 10 3.1 MOV Functional Margin. Gate valves are available with different disks or wedges. The bonnet, which containing the moving parts, is attached to the body, usually with bolts, to permit maintenance. F: Double-disc non-rising-stem gate valve, Fig. 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 I. Gate valves are primarily designed to start or stop flow, and when a straight-line flow of fluid and minimum flow restriction are needed. The typical applications of conduit valves include dirty river water with suspended solids or water with sludge or debris. Seat ring construction provides seats which are either threaded into position or are pressed into position and seal welded to the valve body. | 35 | ), ( In the main Menu "Valves" you will find links to detailed (large) drawings of both stem types. To prevent leakage, in the area of the seal, a fine surface finish of the stem is necessary. The valve trim consists of the stem, the gate, the disc or wedge and the seat rings. A Gate valve can be used for a wide range of liquids and provides a tight seal when closed. These valves are used in pipelines where pigs are run through the piping to perform cleaning of builtup deposits or debris. 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. | In the double-disc parallel-seat valves (Figs. In split-wedge gate valves (Fig. Specifically, gate valves are used in applications requiring a straight-line flow of fluid with minimum . ), ( Gate valves … 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. 57 Just enter your email address: You will receive a confirmation email to confirm the subscription. Seats for Gate valves are either provided integral with the valve body or in a seat ring type of construction. ), Gate Valve Types, Construction, Applications and Advantages, Post Comments G: Parallel-seat gate valve showing welded construction for high-temperature service with welded-in seat ring, Fig. 347 0 obj <>stream This leaves an opening for flow through the valve at the same inside diameter as the pipesystem in which the valve is installed. Pressure Binding Sometimes in high-temperature applications, the flow medium, such as water or steam, is trapped in the valve bonnet area when the valve … Also, the non-rising stem valve is preferred for buried service. An evaluation of the operation of a motor-operated gate valve begins with two simple questions. In service, these valves generally are either fully open or fully closed. For a valve of the Rising Stem type, the stem will rise above the handwheel if the valve is opened. 133 ), ( 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. ), ( This wedge type consists of two-piece construction which seats between the tapered seats in the valve body. Split-wedge or flexible-wedge type gate valves are expected to perform better than solid-wedge gate valves when thermal binding is a concern. However, it is generally preferred because the position of the stem indicates at once whether the valve is open or closed. PIPING GUIDE Gate valves consists of three main parts: body, bonnet, and trim. Gate valves are general service valves primarily used for on/off, non-throttling service. Gate Valves. Solid-wedge gate valves are considered the most economical. %%EOF .iW� ڑ���3�֍Ȯ�����#�M���P�$��#�Τx��. The inside diameter of a conduit gate valve is equal to the inside diameter of the connecting pipe. Almost all small, NPS 2 (DN 50) and smaller, gate valves are solid-wedge gate valves. 1 When the valve is closed, the gate disc is wedged on both sides against the seat. 4 E: Double-disc rising-stem flanged-end gate valve for 150-psig service, Fig. A hollow wedge is a variation of solid wedge with the exception of a hole in the center. 322 0 obj <> endobj ), ( This is particularly important where motors are used for opening and closing the valve. 79 The hollow wedge travels along the stem when the threaded stem is rotated, thus opening or closing the valve port. ( A Yoke is an integral part from a Rising Stem valve and is mounted to the Bonnet. the discs are forced against the valve seats by a wedging mechanism as the stem is tightened. h��V�o�0�W��=t��D�*+[��V Z'U}� �hI���ߝ��x��p�s_�����B$�!� ,����h\�Z� Allowable Stress for Piping Materials … 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 C: Non-rising stem gate valve for 250-psig steam service, Fig. Write For Us, Gate valves are primarily designed to serve as. ), ( 85 Pressure binding may not occur if the leakage past the upstream seat is Rings with hard facings may be supplied for the application where they are required. | This happens, because the stem is threaded and mated with the bushing threads of a Yoke. the two-piece wedge disc is seated between matching tapered seats in the body. H: Pressure binding caused by built-up pressure in bonnet cavity, Fig. Like the double-disc or parallel-seated gate valve, its disc seats against the downstream seat, depending on the flow direction. Stress Theory. The body is generally connected to other equipment by means of flanged, screwed or welded connections. the operating threads are out of direct contact with the fluid or gas. ), ( Sitemap, About Us The solid wedge is a single-piece solid construction. ), ( This type of wedge is suitable for the treatment of non-condensing gases and liquids at normal temperatures, particularly corrosive liquids. © 2011 It is common practice to use cast iron or ductile iron solid-wedge gate valves in cold or ambient water lines. 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. is preferred where space is limited and where the fluid passing through the valve will not corrode or erode the threads or leave deposits on the threads. This valve shall be opened during start up. ), ( 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. It does not compensate for changes in seat alignment due to pipe end loads or thermal fluctuations. ToS The design of the wastegate body and valve determine the … For a valve of the non Rising Stem type, there is no upward stem movement if the valve is opened. Stems are usually forged, and connected to the disk by threaded or other techniques. endstream endobj startxref adequate to prevent over pressurization of the valve bonnet cavity. ), ( This type is preferred where the body seats might be distorted due to pipeline strain. 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 . In the open position, the wedge is completely out of the flow stream. Get all new articles & jobs directly in your inbox. 2 As such it is most susceptible to leakage.