Why is the valve set like this?

This regulation applies to the setting of gate valves, stop valves, ball valves, butterfly valves and pressure reducing valves in petrochemical plants. The setting of check valves, safety valves, regulating valves and steam traps is subject to relevant regulations. This regulation does not apply to the setting of valves on underground water supply and drainage pipelines.

First, valve layout principles

1. Valves should be set according to the type and quantity shown on the pipeline and instrument flow diagram (PID). When PID has specific requirements for the installation position of certain valves, they should be set according to process requirements.
2. Valves should be arranged in places that are easy to access, operate and maintain. Valves on rows of pipes should be arranged in a centralized manner, and consider setting up operating platforms or ladders.

Second, valve installation location requirements

1. When the pipe gallery pipelines entering and exiting the device are connected to the main pipes on the pipe gallery of the entire plant, a shut-off valve must be installed. The installation location of the valve should be centralized on one side of the device area, and necessary operating platforms or maintenance platforms should be set up.
2. Valves that need to be frequently operated, maintained and replaced should be located in places that are easily accessible on the ground, platform or ladder. Pneumatic and electric valves should also be placed in easily accessible places.
3. Valves that do not need to be operated frequently (only used when starting and stopping) should also be placed in places where temporary ladders can be set up if they cannot be operated on the ground.
4. The height of the center of the valve handwheel from the operating surface is between 750 and 1500mm, and the most suitable height is 1200mm. The installation height of valves that do not need to be operated frequently can reach 1500-1800mm. When the installation height cannot be lowered and frequent operation is required, an operating platform or step should be set during the design. Valves on pipelines and equipment of hazardous media shall not be set within the height range of a person's head.
5. When the height of the center of the valve handwheel from the operating surface exceeds 1800mm, a sprocket operation should be set. The chain distance of the sprocket from the ground should be about 800mm. A sprocket hook should be set to hang the lower end of the chain on a nearby wall or pillar to avoid affecting the passage.
6. For valves set in the trench, when the trench cover can be opened to operate, 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 set to make its handwheel within 100mm below the trench cover.
7. For valves set in the trench, when it needs to be operated on the ground, or valves installed under the upper floor (platform), a valve extension rod can be set to extend it to the trench cover, floor, or platform for operation. The handwheel of the extension rod should be 1200mm away from the operating surface. 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 damage to the valve. Normally, the sprocket or extension rod should be used as little as possible to operate the valve.
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 valve stem and handwheel extend into the upper part of the platform and the height is less than 2000mm, it should not affect the operation and passage of the operator to avoid personal injury.

Third, the setting requirements of large valves

1. The operation of large valves should use a gear transmission mechanism, and the space required for the transmission mechanism should be considered when setting. Generally, valves with a size larger than the following grades should consider using a valve with a gear transmission mechanism.
2. Large valves should be equipped with brackets on one or both sides of the valve. The bracket should not be installed on a short pipe that needs to be disassembled during maintenance, and the support of the pipeline should not be affected when the valve is removed. The distance between the bracket and the valve flange should generally be greater than 300mm.
3. The installation location of large valves should have a site for using a crane, or consider setting up a hanging column or hanging beam.

Fourth, the requirements for the installation of valves on horizontal pipelines

1. Unless there are special requirements for the process, the handwheel of the valve installed on the horizontal pipeline shall not be downward, especially the handwheel of the valve on the pipeline of dangerous media is strictly prohibited to be downward. The orientation of the valve handwheel is determined in the following order: vertically upward; horizontally; vertically upward with a left or right tilt of 45°; vertically downward with a left or right tilt of 45°; not vertically downward.
2. For horizontally installed open-stem valves, when the valve is opened, the valve stem shall not affect the passage, especially when the valve stem is located at the head or knee of the operator.

Fifth, other requirements for valve installation

1. For valves arranged on parallel pipelines, their center lines should be aligned as much as possible. When the valves are arranged adjacently, the net distance between the handwheels should not be less than 100mm; the valves can also be staggered to reduce the distance between pipelines.
2. For valves that are required to be connected to the equipment pipe mouth in the process, when the nominal diameter, nominal pressure, sealing surface type, etc. are the same or matching with the equipment pipe mouth flange, they should be directly connected to the equipment pipe mouth. When the valve has a concave flange, the equipment professional should be asked to configure a convex flange at the corresponding pipe mouth.
3. Unless there are special requirements for the process, the valves on the bottom pipes of towers, reactors, vertical containers and other equipment shall not be arranged in the skirt.
4. When the branch pipe is led out from the main pipe, its shut-off valve should be set on the horizontal section of the branch pipe close to the root of the main pipe so that the fluid can be drained to both sides of the valve.
5. The branch pipe shut-off valve on the pipe gallery is not often operated (only used when parking for maintenance). If there is no permanent ladder, consider leaving space for the use of temporary ladders.
6. The high-pressure valve has a large starting force when it is opened. A bracket must be set up to support the valve and reduce the starting stress. The installation height should be 500-1200mm.
7. The fire water valves, fire steam valves, etc. in the device boundary area should be dispersed and in a safe area that is easy for operators to access in the event of an accident.
8. The valve group of the fire-extinguishing steam distribution pipe of the heating furnace should be easy to operate, and the distribution pipe should not be less than 7.5m away from the furnace body.
9. When installing threaded valves on the pipeline, a flexible joint must be installed near the valve for easy disassembly.
10. Wafer valves or butterfly valves shall not be directly connected to the flanges of other valves and pipe fittings. A short pipe with flanges on both ends should be added in the middle.
11. The valve should not be subjected to external loads to avoid excessive stress and damage to the valve