Principles of valve arrangement

The valve should be arranged in a place that is easily accessible, easy to operate and maintain. Valves on rows of pipes should be centrally arranged, and consideration should be given to setting up operating platforms or ladders.

Installation position requirements for valves

When the pipe in and out of the device is connected with the main pipe on the pipe gallery of the whole plant, a cut-off valve must be installed. The installation position of the valve should be centrally arranged on the side of the installation area, and the necessary operating platform or maintenance platform should be set.

Valves that require frequent operation, service and replacement should be located on the ground, on platforms or within easy reach of ladders. Pneumatic and electric valves should likewise be conveniently located.

Valves that do not require frequent operation (only used when opening and stopping), and should also be placed in a place where temporary ladders can be erected if they cannot be operated on the ground.

The height of the center of the valve handwheel from the operating surface is between 750~1500mm, the most suitable height is 1200mm, and the installation height of the valve that does not require frequent operation can reach 1500~1800mm. When the installation height cannot be lowered and frequent operation is required, the operating platform or step should be set when designing. Valves in pipelines and equipment of hazardous media shall not be set within the height of the head of a person.

When the height of the center of the valve handwheel from the operating surface exceeds 1800mm, the sprocket operation should be set, the chain distance 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 a nearby wall or column to avoid affecting the passage of the passage.

The valve set in the pipe trench, when the trench cover plate can be operated, the handwheel of the valve should not be lower than 300mm under the trench cover, when it is lower than 300mm, the valve extension rod should be set so that the handwheel is within 100mm under the trench cover.

When the valve set in the pipe trench needs to be operated on the ground, or the valve installed under the previous floor (platform), the valve extension rod can be set to extend to the trench cover, floor, platform operation, and the handwheel track of the extension rod is 1200mm is appropriate. Valves with nominal diameters less than or equal to DN40 and threaded connections should not be operated with sprockets or elongators to avoid damage to the valves. In general, valves should be operated with sprockets or elongators as little as possible.

When the valve set in the pipe trench needs to be operated on the ground, or the valve installed under the previous floor (platform), the valve extension rod can be set to extend to the trench cover, floor, platform operation, and the handwheel track of the extension rod is 1200mm is appropriate. Valves with nominal diameters less than or equal to DN40 and threaded connections should not be operated with sprockets or elongators to avoid damage to the valves. In general, valves should be operated with sprockets or elongators as little as possible.

Setting requirements for large valves

The operation of large valves should use a geared transmission mechanism, and the space position required by the transmission mechanism should be considered when setting. Generally, valves larger than the following grades should be considered for the use of valves with gear transmission mechanisms.

Large valves should be provided with brackets on one or both sides of the valve, which should not be located on the short pipe that needs to be disassembled during maintenance, and consider that the support of the pipeline should not be affected when removing the valve. Generally, the distance between the bracket and the valve flange should be greater than 300mm.

The installation location of large valves should have a site for the use of cranes, or consider setting up hanging columns and beams.

Requirements for setting valves on horizontal pipes

In addition to other special requirements of the process, the valve handwheel installed on the general horizontal pipeline shall not face down, especially the valve on the pipeline of dangerous media is strictly forbidden to face down. The orientation of the valve handwheel is determined in the following order: vertically upward; Level; Tilt left and right vertically by 45°; Tilt left and right vertically down by 45°; Must not be vertically downward.

Horizontally installed open stem valves, when the valve is opened, the stem must not affect the passage, especially when the stem is located on the head or knee of the operator.

Additional requirements for valve settings

The center line of the valve on the parallel arrangement pipeline should be as complete as possible, and when the valve is arranged next to each other, the clear distance between the handwheels should not be less than 100mm; Valves can also be staggered to reduce pipe spacing.

The valve that is required to be connected to the nozzle of the equipment should be directly connected to the nozzle of the equipment when the nominal diameter, nominal pressure, sealing surface type, etc. are the same or compatible with the flange of the nozzle of the equipment. When the valve is concave flange, the equipment should be requested to configure a convex flange at the corresponding nozzle.

In addition to special requirements for the process, valves on the bottom pipelines of towers, reactors, vertical vessels and other equipment shall not be arranged in the skirt.

When leading the branch pipe from the main pipe, the shut-off valve should be located 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.

Branch shut-off valves on the pipe gallery are not operated frequently (only used when stopped for maintenance), and if there is no permanent ladder, you should consider leaving a space for the use of temporary ladders.

When the high-pressure valve is opened, the starting force is large, and a bracket must be set to support the valve and reduce the starting stress, and its installation height is 500~1200mm.

Fire water valves, fire steam valves, etc. in the installation boundary area should be dispersed, and in a safe area that is easily accessible to operators in the event of an accident.

The valve group of the fire extinguishing steam distribution pipe of the heating furnace should be easy to operate, and the distance between the distribution pipe and the furnace body should not be less than 7.5m.

When installing a threaded valve on a pipeline, a union must be installed near the valve for removal.

The clamp valve or butterfly valve shall not be directly connected to the flange of other valves and pipe fittings, and a short pipe with flanges at both ends should be added in the middle.

The valve should not withstand external load, so as not to damage the valve under excessive stress.