A valve is a pipeline accessory used to open and close pipelines, control flow direction, and regulate and control the conveying medium’s parameters (temperature, pressure, and flow). It is an important component of the industrial pipeline system and plays an important role in production.
The Main functions of the valve
- 1. Connecting and cutting off the medium. gate valves, butterfly valves, and ball valves can be selected;
- 2. Prevent medium backflow. a check valve can be selected;
- 3. Regulating medium pressure and flow rate. globe valve and regulating valve can be selected;
- 4. Separation, mixing, or distribution of media. Plug valves, gate valves, and regulating valves can be selected;
- 5. Safety valves and breathing valves can be selected to prevent the medium pressure from exceeding the specified value to ensure the safe operation of pipelines or equipment.
Suggestions for the reasonable arrangement of valves
The reasonable arrangement of valves involves multiple aspects, including engineering design, safety considerations, operation and maintenance, and economic factors. Here are some suggestions for the reasonable arrangement of valves:
Engineering design considerations:
Select the appropriate valve material and type based on the fluid properties (such as corrosiveness, viscosity, temperature, etc.).
The valve size should match the pipeline to ensure that flow and pressure losses are within an acceptable range.
Valves should be kept away from high-temperature areas and flammable and explosive areas.
For situations that may cause overpressure in pipelines or equipment, consideration should be given to configuring safety valves or pressure relief valves.
Operation and Maintenance:
Valves should be installed in easily accessible and operable locations, especially those that require frequent operation.
Consider valve maintenance and leave sufficient space for valve disassembly.
For valves requiring frequent inspection or maintenance, they should be installed on the ground or platform, avoiding high altitude or difficult to access positions.
Consider the simplicity and efficiency of the layout, avoiding the use of excessive elbows and accessories.
Choose valves with lower economic lifespan and maintenance costs.
The arrangement of valves should make them easy to identify and operate.
If possible, consider using automatic or remote-control valves.
For valves requiring manual operation, the handle or lever should face the operator and not obstruct the passage or walkway.
In specific applications such as cleanrooms or food factories, valves, and pipelines should avoid dead corners to prevent contamination or bacterial growth.
In short, the reasonable arrangement of valves should ensure their functionality and efficiency and consider the convenience, safety, and maintenance of operation. It is crucial to combine the actual on-site situation and operational requirements for layout during design.
Principles of valve arrangement
1. Valves should be arranged in places that are easy to access, operate, and maintain. The valves on rows of pipelines should be centrally arranged and equipped with operating platforms and ladders.
2. The distance between the center of the valve handwheel on the vertical pipeline and the operating surface should be 1.2m, and the maximum distance should not exceed 2m.
3. When the height of the valve handwheel center exceeds 2m from the operating surface, the following measures can be taken:
- (1) Valves that are not frequently operated can be equipped with ladders, movable platforms, or sprockets;
- (2) Frequently operated or centrally arranged group valves should have an operating platform.
4. Valves on pipelines and equipment with extremely hazardous or highly corrosive media should not be placed within the height range of a person’s head.
5. The valve should be arranged in a position where the displacement of the pipeline is small.
6. The center of the valve handwheel arranged around the operating platform should not be greater than 450mm from the edge of the operating platform. When the valve stem and handwheel extend above the platform, and the height is less than 2m, it should not hinder the operation and passage of the operator.
7. When a rising stem valve with a horizontally installed valve stem is opened, the valve stem must not obstruct personnel’s passage.
8. When the valves are arranged adjacent, the clear distance between the handwheels should be at least 100mm.
9. The direction of the valve stem on a horizontal pipeline shall not be vertically downward, and the direction of the valve stem can be determined in the following order:
- (1) Vertical upward;
- (2) Horizontal;
- (3) Tilt upwards by 45°;
- (4) Tilt down 45°.
10. Valves on low-temperature medium pipelines should be installed on horizontal pipelines, and the direction of the valve stem should be vertical and upward.
11. The exhaust holes should be arranged toward the high-pressure side of the pipeline system for valves with exhaust holes.
12. Unless there are special requirements for the process, valves on the bottom pipelines of equipment such as towers, reactors, or vertical vessels shall not be arranged inside skirts.
13. The extraction pipeline of liquefied hydrocarbon equipment should be equipped with a shut-off valve near the root of the equipment. When the distance between liquefied hydrocarbon equipment with a volume exceeding 50m3 and its extraction pump is less than 15m, the shut-off valve should be a remote control valve with manual function, and the distance between the local operation button of the remote control valve and the extraction pump should not be less than 15m.
14. The emergency shut-off valve on the combustible liquid input pipeline should not be less than 10m from the edge of the railway loading and unloading stack. When there is no buffer tank in the car loading and unloading station, the distance between the emergency shut-off valve on the loading and unloading pipeline and the loading and unloading crane position should not be less than 10m.
15. The valve isolating equipment should be directly connected to or near the pipe opening. When connecting to equipment with extremely hazardous and highly hazardous media, the valve on the pipeline should be directly connected to the equipment nozzle, and the valve should not be operated with a sprocket.
16. The cut-off valve for the horizontal branch pipe led out from the main pipe should be located on the horizontal pipe section near the main pipe.
17. The pipeline layout should not allow the valve to withstand excessive loads.
18. Valves on underground pipelines should be arranged in valve wells or trenches. If there are process requirements, valve extension rods can be set.
19. The valve arrangement on the fire-extinguishing steam pipeline should meet the following requirements:
- (1) The distance between the valve on the steam sieve tube and the protected equipment of gas or liquid with an operating temperature equal to or higher than the self-ignition point should not be less than 7.5m;
- (2) The valves on the fire extinguishing steam pipeline should be arranged in a safe and easy-to-operate location.
20. For towers and containers with a volume greater than 10m3, emergency isolation valves should be installed on the suction main pipe between them and the high-temperature oil pump. Electric or pneumatic actuators should be selected, and the distance between the isolation valve position and the pump should be ≥ 6m.
21. For high-temperature oil pump inlet and outlet valves with a diameter greater than DN300, electric or pneumatic gate valves should be selected to cut off materials in case of accidents quickly.