The Correct Way to Set Up Industrial Valves

The following regulations apply to the installation of gate valves, globe valves, ball valves, butterfly valves, and pressure-reducing valves in petrochemical plants. The installation of check valves, safety valves, regulating valves, and steam trap valves is governed by other relevant regulations. These provisions do not apply to valves installed in underground drainage and sewage systems.

1. Valve Layout Principles

1.1 Valves should be installed according to the types and quantities indicated on the piping and instrumentation diagram (PID). If the PID specifies the installation locations of certain valves, they should be installed according to the process requirements.

1.2 Valves should be installed in locations that are easy to access and facilitate operation and maintenance. Valves on pipelines arranged in rows should be grouped together, with consideration given to providing operational platforms or ladders.

2. Valve Installation Location Requirements

2.1 For pipelines leading into or out of the installation, when connecting to the main pipeline in the plant corridor, shut-off valves should be installed. The valve installation location should be concentrated on one side of the installation area, with necessary operational or maintenance platforms.

2.2 Valves that require frequent operation, maintenance, and replacement should be located in areas easily accessible from the ground, platforms, or ladders. Pneumatic and electric valves should also be located in easily accessible areas.

2.3 Valves that are not frequently operated (only used during startup or shutdown) should be installed in locations where temporary ladders can be set up if they cannot be operated from the ground.

2.4 The center height of valve handwheels from the operating surface should be between 750mm and 1500mm, with the optimal height being 1200mm. For valves that are not frequently operated, the installation height may reach 1500mm to 1800mm. When the installation height cannot be lowered and frequent operation is required, an operational platform or steps should be provided. Valves on pipelines and equipment with hazardous materials should not be installed at head height.

2.5 When the center height of the valve handwheel exceeds 1800mm, a chain wheel operation system should be installed. The chain's distance from the ground should be around 800mm, and a chain hook should be provided to hang the chain end on a nearby wall or column to avoid obstructing passage.

2.6 For valves located in trenches, if the cover plate can be opened to operate, the valve handwheel should not be lower than 300mm from the trench cover plate. If it is lower than 300mm, an extension rod should be used to ensure the handwheel is within 100mm below the trench cover plate.

2.7 For valves located in trenches that need to be operated from the ground or installed below a platform or floor, extension rods should be provided to extend the valve to the operating surface above the cover plate or platform, with the handwheel distance from the operating surface being 1200mm. Valves with a nominal diameter of DN40 or smaller and threaded connections should not use chain wheels or extension rods to avoid damaging the valve. Generally, the use of chain wheels or extension rods should be minimized.

2.8 The distance between the handwheel and the edge of a platform should not exceed 450mm. When the valve stem and handwheel protrude into the platform area and the height is less than 2000mm, care should be taken to ensure they do not interfere with the operator's operations or passage, to avoid injury.

3. Large Valve Installation Requirements

3.1 The operation of large valves should use gear-operated mechanisms. The installation should consider the space required for the drive mechanism. Generally, valves larger than the following sizes should consider using gear-operated mechanisms.

3.2 Large valves should be supported on one or both sides, and these supports should not be installed on short pipes that need to be removed during maintenance. When removing the valve, it should not affect the support of the pipeline. Generally, the distance between the support and the valve flange should be greater than 300mm.

3.3 The installation location of large valves should have space for the use of a crane or should consider providing hoist columns or beams.

4. Valve Installation Requirements on Horizontal Pipelines

4.1 Except where the process has special requirements, the handwheels of valves installed on horizontal pipelines should not face downward, especially for valves on pipelines carrying hazardous materials. The orientation of the valve handwheel should be determined in the following order: vertical upward; horizontal; 45° left or right inclined from vertical upward; 45° left or right inclined from vertical downward; and should never face downward.

4.2 For horizontal installations of rising stem valves, the valve stem should not obstruct passage when the valve is open, especially when the valve stem is at head or knee level.

5. Other Valve Installation Requirements

5.1 On pipelines arranged in parallel, the centerlines of the valves should be as aligned as possible. The clearance between the handwheels of adjacent valves should not be less than 100mm. Valves can also be staggered to reduce the pipeline spacing.

5.2 Valves required by the process to be connected to equipment nozzles should be directly connected to the nozzle when the nominal diameter, pressure rating, and sealing surface type match the equipment nozzle flange. When the valve has a concave flange, the equipment specialist should configure a convex flange on the corresponding nozzle.

5.3 Except where the process has special requirements, valves at the bottom of the pipes for towers, reactors, and vertical containers should not be installed within the skirt structure.

5.4 When drawing a branch from a main pipeline, the shut-off valve should be installed near the horizontal section of the branch pipe at the root of the main pipeline to ensure the fluid is cleared from both sides of the valve.

5.5 Shut-off valves on branch pipes in the pipeline corridor that are not frequently operated (only used during shutdowns for maintenance) should leave space for temporary ladders if no permanent ladder is installed.

5.6 High-pressure valves, which require a large opening force, should be supported to reduce starting stress, and their installation height should be between 500mm and 1200mm.

5.7 Firewater valves, steam valves, etc., in the installation area should be dispersed and located in safe areas where operators can easily access them in case of an emergency.

5.8 The valve group for the fire extinguishing steam distribution pipe of a heating furnace should be easy to operate, and the distribution pipe should be at least 7.5m from the furnace.

5.9 When installing threaded connection valves, unions should be installed near the valve to facilitate disassembly.

5.10 Flanged butterfly valves or wafer valves should not be connected directly to other valves or pipe fittings. A short pipe with flanges at both ends should be inserted in between.

5.11 Valves should not bear external loads to avoid excessive stress that may damage the valve.

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