The requirements for valve installation specifications mainly include on-site inspection, installation location, installation operation, and other aspects. The following is a detailed introduction:
\nRequirements for valve entry inspection
\nModel and specification: The model and specification of the valve should meet the design requirements.
\nAccessories and appearance: Valves and their accessories should be fully equipped and free from processing defects and mechanical damage.
\nMarking requirements: In addition to trademarks, models, specifications, and other markings, check valves should also have markings indicating the direction of water flow.
\nAction and Cleaning: The valve disc and operating mechanism of the valve should move flexibly without jamming, and the valve body should be clean and free of foreign objects blocking.
\nRequirements for valve installation position
\nOverall layout: Valves should be placed in easily accessible, easy to operate, and maintain locations. Valves on rows of pipelines should be arranged in a centralized manner, and consideration should be given to setting up operating platforms or ladders.
\nDevice related: When the pipe gallery pipelines entering and exiting the device are connected to the main pipes on the entire plant pipe gallery, cut-off valves must be installed, and the installation position should be centrally arranged on one side of the device area, with necessary operating or maintenance platforms set up.
\nOperational convenience
\nValves that require frequent operation, maintenance, and replacement should be located on the ground, platform, or ladder where they are easily accessible. Pneumatic and electric valves should also be arranged in easily accessible locations.
\nValves that do not require frequent operation (only used for opening and stopping) should also be arranged in places where temporary ladders can be erected if they cannot be operated on the ground.
\nHeight requirements
\nThe center height of the valve handwheel from the operating surface is between 750-1500mm, with a suitable height of 1200mm. Valves that do not require frequent operation can be installed at a height of 1500-1800mm. When the installation height cannot be lowered and frequent operation is required, an operating platform or step should be set up during design. Valves on pipelines and equipment containing hazardous media shall not be installed within the height range of a person’s head.
\nWhen the distance between the center of the valve handwheel and the operating surface exceeds 1800mm, it is advisable to install a chain wheel for operation. The chain wheel should be about 800mm above the ground, and a chain wheel hook should be installed to hang the lower end of the chain on a nearby wall or pillar to avoid affecting the passage.
\nValves in the trench: Valves installed in the trench, when the trench cover can be opened for operation, the handwheel of the valve should not be lower than 300mm below the trench cover. When it is lower than 300mm, a valve extension rod should be installed so that its handwheel is within 100mm below the trench cover. When the valve set in the trench needs to be operated on the ground or installed below the upper floor (platform), a valve extension rod can be installed to extend it to the trench cover plate, floor slab, or platform for operation. The distance between the handwheel of the extension rod and the operating surface should be 1200mm. Valves with a nominal diameter less than or equal to DN40 and threaded connections should not be operated using sprockets or extension rods to avoid damaging the valve. Normally, it is advisable to minimize the use of chain wheels or extension rods to operate valves.
\nValves around the platform: The distance between the valve handwheel arranged around the platform and the edge of the platform should not exceed 450mm. When the valve stem and handwheel are inserted above the platform and the height is less than 2000mm, they should not affect the operation and passage of the operator to avoid personal injury.
\nOther special locations
\nUnless there are special requirements for the process, the handwheel of valves installed on horizontal pipelines should not face downwards, especially for valves on hazardous medium pipelines, which are strictly prohibited from facing downwards. The orientation of the valve handwheel is determined in the following order: vertically upward; Level; Vertical upward tilt of 45 degrees to the left and right; Vertical downward tilt of 45 degrees to the left and right; Do not vertically downward.
\nFor horizontally installed open stem valves, the valve stem must not affect passage when the valve is opened, especially when the valve stem is located at the operator’s head or knee.
\nUnless there are special requirements for the process, valves on the bottom pipelines of equipment such as towers, reactors, and vertical vessels shall not be arranged inside the skirt.
\nWhen leading out branch pipes from the main pipe, the shut-off valve should be located on the horizontal section of the branch pipe near the root of the main pipe, so that the fluid can be discharged to both sides of the valve.
\nThe branch shut-off valve on the pipe gallery is not frequently operated (only used during parking maintenance). If there is no permanent ladder installed, consideration should be given to leaving space for the use of temporary ladders.
\nThe fire water valves, fire steam valves, etc. within the device boundary should be arranged in a dispersed manner and in a safe area that is easily accessible to operators in the event of an accident.
\nThe valve group of the fire extinguishing steam distribution pipe for the heating furnace should be easy to operate, and the distance between the distribution pipe and the furnace body should not be less than 7.5m.
\nValve installation and operation requirements
\nAppearance inspection: Before installing the valve, a visual inspection should be conducted, and the valve nameplate should comply with the current national standard “General Valve Marking” GB12220.
\nInsulated pipeline valves: All types of manual valves installed on insulated pipelines must not have handles facing downwards.
\nInstallation direction and connection: The position and inlet\/outlet direction of the valve installation should be correct and easy to operate; The connection should be firm and tight, with flexible opening and closing; The arrangement of valves in rows should be neat and aesthetically pleasing, with an allowable deviation of 3mm on the same plane.
\nElectric self-control valve: Before installation, the electric self-control valve should undergo individual debugging, including action tests such as opening and closing.
\nDirt remover and filter: The dirt remover should be installed on the pipeline in front of the unit, with the correct direction and easy to clean; The connection with the pipeline should be firm and tight, and its installation position should be convenient for the disassembly and cleaning of the filter screen. The material, specifications, and wrapping method of the filter screen should meet the design requirements.
\nClosed system exhaust and drainage: Closed system pipelines should be equipped with exhaust valves at high points of the system and all high points where air may accumulate, and drainage pipes and valves should be installed at low points of the pipeline.
\nHandling and lifting: When handling valves, it is not allowed to throw them casually; When lifting, the rope should be tied to the flange connection between the valve body and the valve cover, and should not be tied to the handwheel or valve stem.
\nClosed state and medium direction: When installing the central air conditioning valve, it should be kept closed and attention should be paid to the characteristics of the valve and the direction of medium flow.
\nConnecting bolts and threads
\nWhen connecting the air conditioning valve to the pipeline, do not forcefully tighten the connecting bolts on its flange; For valves with threaded connections, the threads should be intact and undamaged. When tightening, it is advisable to use a wrench to hold the hexagonal body at one end of the valve. When installing threaded valves, a flexible joint should generally be added at the outlet end of the valve.
\nThreaded valves should be tightly connected to pipelines, and for the convenience of maintenance, galvanized joints should be added in front of valves in important parts.
\nGasket requirements: Asbestos rubber gaskets should be added between flange valves and flanges (except for clamp type butterfly valves).
\nAdjustment handle position: The adjustment handle of the valve should be located at a convenient position for adjustment. Generally, the operating handle of the valve (especially the electric actuator of the electric valve) should not be downward.
\nAvoid obstacles: The installation position of the valve should avoid walls or other places that may prevent valve operation and maintenance.
\nRequirements for large valves
\nThe operation of large valves should use a gear transmission mechanism, and the required spatial position of the transmission mechanism should be considered when setting it up. Usually, valves with gear transmission mechanisms should be considered for sizes larger than a certain level.
\nLarge valves should be equipped with brackets on one or both sides of the valve. These brackets should not be installed on short pipes that need to be disassembled during maintenance, and the removal of the valve should not affect the support of the pipeline. The distance between the general bracket and the valve flange should be greater than 300mm.
\nThe installation location of large valves should have a site for using cranes, or consider installing suspension columns and beams.
\nOther requirements
\nValves arranged in parallel on pipelines should have their centerlines aligned as much as possible. When valves are arranged adjacent to each other, the clear distance between the handwheels should not be less than 100mm; Valves can also be arranged in a staggered manner to reduce the spacing between pipelines.
\nValves that are required to be connected to the equipment pipe mouth in terms of process should be directly connected to the equipment pipe mouth when their nominal diameter, nominal pressure, sealing surface type, etc. are the same or match the flange of the equipment pipe mouth. When the valve has a concave flange, it is necessary to request the equipment professional to configure a convex flange at the corresponding pipe opening.
\nWhen the high-pressure valve is opened, the starting force is large, and a bracket must be set up to support the valve and reduce the starting stress. The installation height should be 500-1200mm.
\nWhen installing threaded valves on pipelines, a flexible joint must be installed near the valve for easy disassembly.
\nClamp type valves or butterfly valves shall not be directly connected to the flanges of other valves and fittings, and a short pipe with flanges at both ends shall be added in the middle.
\nValves should not withstand external loads to prevent damage from excessive stress.
\nOther checks before installation
\nSelection verification: Select valves based on the purpose of the valve, the characteristics of the medium, maximum working pressure, maximum temperature, as well as the flow rate, flow rate, or nominal diameter of the pipeline. Before installation, carefully check whether the models and specifications of all valves meet the design requirements.
\nPerformance inspection: According to the valve model and factory manual, check whether they can be applied under the required conditions, and if necessary, conduct water or air pressure tests.
\nComponent inspection: Check if the packing is intact, if the gland bolts have sufficient adjustment allowance, if the valve stem and disc are in good condition, and if there is any jamming or tilting phenomenon. The sealing surface of the valve disc must be tightly closed, and for valves with threaded connections, the quality of the threads should be checked. Unqualified valves cannot be installed.<\/p>\n","protected":false},"excerpt":{"rendered":"
The requirements for valve installation specifications […]<\/p>\n","protected":false},"author":1,"featured_media":236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[12],"tags":[],"class_list":["post-410","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-home-valve"],"acf":[],"yoast_head":"\n