This provision applies to the setting of gate valves, globe valves, ball valves, butterfly valves and pressure-reducing valves in petrochemical plants. Refer to relevant regulations for the settings of check valves, safety valves, regulating valves and steam traps. This provision does not apply to the setting of valves on underground water supply and drainage pipelines.
1 Arrangement principles of valves
1.1 Valves should be set according to the type and quantity showed on the pipeline and instrument flow diagram (PID). When PID has specific requirements for the installation position of some valves, it should be set according to the process requirements.
1.2 Valves should be arranged in places that are easy to access, operate and maintain. The valves on the pipelines in rows should be arranged centrally, and consideration should be given to setting up operating platforms or ladders.
2 Requirements for the installation position of the valve
2.1 When the pipe gallery pipes entering and exiting the device are connected to the main pipe on the pipe gallery of the whole plant, valves for cutting must be set. The installation position of the valves should be concentrated on one side of the device area, and the necessary operation platform or maintenance platform should be set up.
2.2 Valves that require frequent operation, maintenance and replacement should be located on the ground, on platforms or easily accessible by ladders. Pneumatic and electric valves should likewise be located within easy reach.
2.3 Valves that do not need to be operated frequently (only used when starting and stopping), if they cannot be operated on the ground, they should also be arranged where temporary ladders can be erected.
2.4 The height from the center of the valve handwheel to the operating surface is between 750 and 1500mm, and the most suitable height is
1200mm, and the installation height of valves that do not require frequent operation can reach 1500-1800mm. When the installation height cannot be lowered and frequent operations are required, an operating platform or steps should be provided during design. The valves on pipelines and equipment for hazardous media shall not be set within the height range of a person’s head.
2.5 When the height between the center of the valve handwheel and the operating surface exceeds 1800mm, it is advisable to set up a sprocket for operation. The chain of the sprocket should be about 800mm from the ground, and a sprocket hook should be provided to hang the lower end of the chain on a nearby wall or pillar. on, so as not to affect the passage of the channel
2.6 For the valves installed in the pipe ditch, when the ditch cover plate can be opened to operate, the hand wheel of the valve should not be lower than 300mm below the ditch cover plate. Within 100mm below the ditch cover.
2.7 When the valve installed in the pipe trench needs to be operated on the ground, or the valve installed under the upper floor (platform), the valve extension rod can be set to extend to the trench cover, floor, and platform for operation, the distance between the hand wheel of the extension rod and the operating surface is 1200mm. Valves with a nominal diameter less than and equal to DN40 and threaded connections should not be operated with sprockets or extension rods to avoid damage to the valve. In general, the valve should be operated with as few sprockets or extension rods as possible.
2.8 The distance between the valve hand wheels 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 shall not affect the operation and passage of the operator, so as to avoid personal injury.
3 Setting requirements for large valves
3.1 The operation of large valves should use a gear transmission mechanism, and the space required by the transmission mechanism should be considered when setting. In general, valve sizes larger than those listed below should consider valves with gear transmissions.
3.2 For large valves, brackets should be installed on one or both sides of the valve. The brackets should not be installed on short pipes that need to be disassembled during maintenance, and the support of the pipeline should not be affected when the valve is removed. Generally, the distance between the bracket and the valve flange should be greater than 300mm.
3.3 The installation location of large valves should have a place where cranes can be used, or consider installing hanging columns and hanging beams.
4 Setting requirements for valves on horizontal pipelines
4.1 Unless there are special requirements for the process, the hand wheels of valves installed on general horizontal pipelines must not face downwards, especially the valves on dangerous medium pipelines are strictly prohibited from facing downwards. The orientation of the valve handwheel is determined in the following order: vertically upward; horizontally; vertically upward left and right inclined 45°; vertically downward left and right inclined 45°; not vertically downward.
4.2 For rising stem valves installed horizontally, when the valve is opened, the stem must not affect the traffic, especially when the stem is located on the operator’s head or knees.
5 Other requirements for valve setting
5.1 For the valves arranged in parallel on the pipeline, the centerlines should be aligned as much as possible. When the valves are arranged adjacent to each other, the net distance between the handwheels should not be less than 100mm; the valves can also be arranged staggered to reduce the distance between the pipelines.
5.2 For valves that are required to be connected to equipment nozzles in terms of technology, when the nominal diameter, nominal pressure, and sealing surface type are the same as or match the flanges of the equipment nozzles, they should be directly connected to the equipment nozzles. When the valve has a concave flange, it is necessary to ask the equipment professional to configure a convex flange on the corresponding nozzle.
5.3 Unless the process has special requirements, the valves on the bottom pipes of towers, reactors, vertical vessels and other equipment shall not be arranged in skirts.
5.4 When the branch pipe is led out from the main pipe, the cut-off valve should 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.
5.5 The branch pipe cut-off valve on the pipe gallery is not frequently operated (only used during parking and maintenance). If there is no permanent ladder, it should be considered to reserve a space for using a temporary ladder.
5.6 When the high-pressure valve is opened, the start-up force is large, and a bracket must be installed to support the valve and reduce the start-up stress. The installation height is preferably 500-1200mm.
5.7 Firewater valves, fire steam valves, etc. in the device boundary area should be arranged in a scattered manner, and it should be a safe area that operators can easily access when an accident occurs.
5.8 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.
5.9 When installing a threaded valve on the pipeline, a union must be installed near the valve for easy disassembly.
5.10 Wafer valves or butterfly valves shall not be directly connected to the flanges of other valves and pipe fittings, and a section shall be added in the middle
Short tube with flanges at both ends.
5.11 The valve should not bear the external load, so as not to damage the valve due to excessive stress.