General provisions for valve setting
This regulation is applicable to the setting of gate valve, globe valve, ball valve, butterfly valve and pressure reducing valve in petrochemical plant. See relevant regulations for the setting of check valve, safety valve, regulating valve and drain valve. This regulation is not applicable to the setting of valves on underground water supply and drainage pipelines.
Valve layout principle
Valves shall be set according to the type and quantity shown on the piping and instrument flow diagram (PID). When PID has specific requirements for the installation position of some valves, it shall be set according to the process requirements.
The valve shall be arranged at a place easy to access, operate and maintain. Valves on rows of pipelines shall be arranged in a centralized manner, and operation platforms or ladders shall be considered.
Installation position requirements of valves
When the pipes in and out of the device are connected with the main pipe on the pipe rack of the whole plant, cut-off valves must be set. The installation position of valves shall be centrally arranged on one side of the unit area, and necessary operation platform or maintenance platform shall be set.
Valves requiring frequent operation, maintenance and replacement shall be located on the ground, platform or ladder. Pneumatic and electric valves shall also be arranged at easy access.
Valves that do not need to be operated frequently (only used when starting and stopping) shall also be arranged where temporary ladders can be erected if they cannot be operated on the ground.
The height between the center of the valve handwheel and the operating surface is 750-1500mm, and the most suitable height is
1200mm, the installation height of valves that do not need frequent operation can reach 1500-1800mm. When the installation height cannot be reduced and frequent operation is required, an operation platform or step shall be set in the design. Valves on pipelines and equipment with hazardous media shall not be set within the height range of human head.
When the height between the center of the valve handwheel and the operating surface exceeds 1800mm, a sprocket should be set for operation. The chain of the sprocket should be about 800mm from the ground, and a sprocket hook should be set to hang the lower end of the chain on the nearby wall or column to avoid affecting the passage.
For the valve set in the pipe trench, when the trench cover plate can be opened for operation, the hand wheel of the valve shall not be lower than 300mm under the trench cover plate. When it is lower than 300mm, the valve extension rod shall be set to make the hand wheel within 100mm under the trench cover plate.
When the valve set in the pipe trench needs to be operated on the ground, or the valve installed below the upper floor (platform), the valve extension rod can be set to extend to the trench cover plate, floor and platform for operation. The hand track operating surface of the extension rod is 1200mm. Valves with nominal diameter less than or equal to Dn40 and threaded connection shall not be operated with sprocket or extension rod to avoid damage to the valve. In general, the use of sprockets or extension rods to operate the valve should be minimized.
The distance between the valve handwheel arranged around the platform and the edge of the platform shall not be greater than 450mm. When the valve stem and hand wheel extend above the platform and the height is less than 2000mm, it shall not affect the operation and passage of operators to avoid personal injury.
Setting requirements for large valves
Gear transmission mechanism shall be used for the operation of large valves, and the space position required by the transmission mechanism shall be considered when setting. Generally, the size of the valve is larger than the size of the following grades, and the valve with gear transmission mechanism shall be considered.
For large valves, supports shall be set on one or both sides of the valve, which shall not be set on the short pipe to be removed during maintenance, and the support of the pipe shall not be affected when the valve is removed. Generally, the distance between the support and the valve flange shall be greater than 300mm.
The installation position of large valves shall have a place for using cranes, or consider setting suspenders and lifting beams.
Setting requirements of valves on Horizontal Pipelines
Unless otherwise required by the process, the valve handwheel installed on the general horizontal pipeline shall not face down, especially the valve on the dangerous medium pipeline shall not face down. The orientation of the valve handwheel shall be determined in the following order: vertical upward; Level; Vertical upward left and right tilt 45 °; Vertical downward left and right tilt 45 °; Do not go down vertically.
For horizontally mounted rising stem valves, when the valve is opened, the valve stem shall not affect the passage, especially when the valve stem is located on the operator’s head or knee.
Other requirements for valve setting
The valves on the pipeline shall be arranged in parallel, and the center line shall be aligned as far as possible. When the valves are arranged adjacent, the clear distance between the hand wheels shall not be less than 100mm; Valves can also be staggered to reduce pipe spacing.
When the nominal diameter, nominal pressure, sealing surface type, etc. of the valve required to be connected with the equipment nozzle in process are the same or matched with the equipment nozzle flange, it shall be directly connected with the equipment nozzle. When the valve is a concave flange, the equipment discipline shall be requested to configure a convex flange at the corresponding nozzle.
Unless there are special requirements for the process, the valves on the bottom pipes of towers, reactors, vertical vessels and other equipment shall not be arranged in the skirt.
When the branch pipe is led out from the main pipe, its shut-off valve shall be set on the horizontal section of the branch pipe near the root of the main pipe, so that the fluid can be drained to both sides of the valve.
The branch pipe shut-off valve on the pipe rack is not operated frequently (only for shutdown and maintenance). If there is no permanent ladder, it shall be considered to reserve a space for using the temporary ladder.
When the high-pressure valve is opened, the starting force is large. A support must be set to support the valve and reduce the starting stress. Its installation height should be 500-1200mm.
Fire water valves, fire steam valves, etc. in the battery limit of the unit shall be distributed and easily accessible to operators in case of accidents.
The valve group of the fire extinguishing steam distribution pipe of the heating furnace shall be easy to operate, and the distance between the distribution pipe and the furnace body shall not be less than 7.5m.
When a threaded valve is installed on the pipeline, a union must be installed near the valve for easy disassembly.
Wafer valves or butterfly valves shall not be directly connected with the flanges of other valves and pipe fittings, and a short pipe with flanges at both ends shall be added in the middle.
The valve should not bear external load to avoid excessive stress damaging the valve.
Source: China Valves Manufacturer – Yaang Pipe Industry Co., Limited (www.sfutube.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Stainless Steel Valves, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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