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Requirements For Valve Settings
Apr 09, 2019

Requirements for Valve Settings

1 Valve Layout Principle

1.1 Valves shall be set according to the type and quantity shown on the piping and instrument flow chart (PID). When the PID has specific requirements for the installation position of some valves, it should be set according to the process requirements.

1.2 Valves should be located in easy access, easy operation and maintenance areas. Valves on rows of pipelines should be centralized, and operation platforms or ladders should be considered.

 

2. Installation Position Requirements for Valves

2.1 When the pipe gallery pipeline of the inlet and outlet device is connected with the main pipe on the gallery of the whole plant, the cut-off valves shall be installed. The installation position of the valve should be centralized on the side of the device area, and the necessary operation platform or maintenance platform should be set up.

2.2 Valves requiring frequent operation, maintenance and replacement shall be located on the ground, platform or easily accessible ladder. Pneumatic and electric valves should also be placed at easy access.

2.3 Valves that do not need to be operated frequently (only when starting or stopping) should also be placed where temporary ladders can be erected if they cannot be operated on the ground.

2.4 The center distance of valve handwheel is 750-1500mm from the operating surface, and the optimum height is 750-1500mm.

1200mm, the installation height of valves without frequent operation can reach 1500-1800mm. When the installation height cannot be reduced and needs frequent operation, the operation platform or step should be set up when designing. Valves on pipes and equipment of dangerous media shall not be set in the range of head height.

2.5 When the height of the center distance of the valve handwheel exceeds 1800 mm, sprocket operation should be set up. The sprocket's chain distance should be about 800 mm on the ground, and sprocket hooks should be set up to hang the lower end of the chain on the wall or pillar nearby so as to avoid affecting the passage.

2.6 Valve set in pipe groove, when opening the groove cover plate can operate, the handwheel of the valve should not be lower than 300 mm under the groove cover plate, and when less than 300 mm, the valve elongation rod should be installed to make the handwheel less than 100 mm under the groove cover plate.

2.7 Valves installed in pipe trenches need to be operated on the ground or installed under the upper floor (platform). Valve elongation rod can be set to extend to the trench cover, floor and platform. The handwheel distance of elongation rod is 1200 mm. Valves with nominal diameter less than or equal to DN40 and threaded connections should not be operated with sprockets or elongation rods to avoid damaging the valves. In general, sprocket or elongation rod should be used as little as possible to operate the valve.

2.8 The distance between the valve handwheel arranged around the platform and the edge of the platform should not be greater than 450mm. When the stem and handwheel reach above the platform and the height is less than 2000 mm, it should not affect the operation and passage of the operator, so as to avoid causing personal injury.

 

3.Setting Requirements for 3 Large Valves

3.1 Gear drive mechanism should be used in the operation of large valves, and the required space position of the drive mechanism should be taken into account when setting up the valve. Generally, valves larger than the size of the following grades should consider the use of gear drive valves.

3.2 Large valves should have brackets on one or both sides of the valve. The brackets should not be placed on short pipes that need to be disassembled during overhaul, and the support of pipes should not be affected when the valve is disassembled. Generally, the distance between bracket and valve flange should be greater than 300 mm.

3.3 The installation location of large valves should be the place where cranes are used, or suspension columns and beams should be considered.

 

4.Requirements for Valve Setting in Horizontal Pipeline

4.1 Valve handwheels installed in general horizontal pipes shall not be downward except for special requirements of process, especially in dangerous medium pipes. Valve handwheel orientation is determined in the following order: vertical upward; horizontal; vertical upward left and right inclination 45 degrees; vertical downward left and right inclination 45 degrees; not vertical downward.

4.2 Open-rod valves installed horizontally shall not affect the passage of the valve stem when the valve is opened, especially when the valve stem is located at the operator's head or knee.

 

5.Other Requirements for Valve Setting

5.1 Valves on pipelines should be arranged in parallel, and the center line should be aligned as far as possible. When the valves are arranged adjacent to each other, the net distance between handwheels should not be less than 100 mm. Valves can also be arranged staggered to reduce the pipeline spacing.

5.2 Valves that are technically required to be connected to the nozzle of the equipment shall be directly connected to the nozzle of the equipment when the nominal diameter, nominal pressure and sealing surface type are identical or matched with the flange of the nozzle of the equipment. When the valve is concave flange, the equipment specialty should be asked to configure the convex flange at the corresponding pipe orifice.

5.3 Valves on bottom pipes of tower, reactor, vertical container and other equipment shall not be arranged in skirts except for special requirements of process.

5.4 When the branch pipe is drawn from the main pipe, the cut-off valve shall 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.

5.5 The branch pipe cut-off valve on the pipe gallery is not often operated (only for parking and maintenance). If there is no permanent ladder, the space for using temporary ladder should be considered.

5.6 High-pressure valves have large start-up force when they are opened. Brackets must be installed to support valves and reduce start-up stress. Its installation height should be 500-1200 mm.

5.7 Fire-fighting water valves and steam valves in the boundary area of the device should be arranged separately, and the safety zone which is accessible to the operators in case of accidents.

 

The valve group of the steam distribution pipe for fire extinguishing in

5.8 reheating furnace should be easy to operate, and the distance between the distribution pipe and the furnace body should not be less than 7.5 M.

5.9 When installing threaded valves in pipelines, live joints must be installed near the valves for disassembly.

5.10 pairs of clamp valves or butterfly valves shall not be directly connected with flanges of other valves and fittings, and a section shall be added in the middle. Short tube with flanges at both ends.

5.11 Valves should not withstand external loads to avoid excessive stress damage to the valve.


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