1.
Principles of installation of valves
1.1 The valve should be set according to the type and quantity showed on the pipeline and instrument flow chart (PID). When there are specific requirements for directions of certain valves in PID, they should be set according to technical requirements.
1.2 The valve should be placed in a place that is easy to access, operate and repair. The valves on the rows of pipelines should be assembled and placed together, and consider setting up operating ladders.
2
The position of the valve
2.1 When the pipe gallery piping at the inlet and outlet equipment is connected with the main pipe on the pipe gallery of the whole factory, a shut off valve must be installed. The valves should be gathered and placed on one side of the equipment area, and necessary operation channels or maintenance channels should be set up.
2.2 Valves required frequent operation, repair and replacement should be placed on the ground, in a channel or close to a ladder. Pneumatic and electric valves should also be installed in a place that is easily reachable.
2.3 For
valves that do not need to be frequently operated, if they cannot be operated on the ground, they should also be installed in a place where a temporary ladder can be used.
2.4 The height between the base of the valve's handwheel and the operating surface is from 750 to 1500 mm. The most suitable height is 1200 mm. The height of the valve that does not require frequent operation can reach from 1500 to 1800 mm. When the height of the valve cannot be lowered and frequent operation is required, operating channels or steps should be set in the design. Pipes and valves with dangerous media should not be installed at a height of a person.
2.5 When the height from the base of the valve's handwheel to the operating surface exceeds 1800 mm, a sprocket wheel should be set for operation. The sprocket should be 800 mm away from the ground, and a sprocket hook should be set up. The lower end of the chain should be hung on the adjacent wall or pillar to avoid affecting the passage.
2.6 For the valve set in the pipe ditch, when the ditch cover is opened for operation, the hand wheel of the valve should not be lower than 300 mm under the ditch cover. When it is less than 300 mm, the valve extension stem should be set to make the hand wheel within 100 mm under the ditch cover.
2.7 When the valve installed in the pipe ditch needs to be operated on the ground or the equipment is under the upper floor (channel), the valve extension stem can be set to extend to the trench cover, floor, and channel. The hand wheel with extend stems should be 1200 mm away from the operating surface. Valves with a nominal diameter less than or equal to DN40 and threaded connections should not be operated with sprockets or extension stems to avoid damage to the valve. Under normal circumstances, sprockets or extension stems should be used less for operating the valve.
2.8 The distance between the hand wheel of the valve placed around the channel and the edge of the channel should not be greater than 450 mm. When the valve stem and hand wheel extend to the upper part of the channel and the height is less than 2000 mm, they should not affect the operation and passage of the operator, avoiding personal injury.
3
Requirements for installation of large valves
3.1 The operation of large valves should use gear transmission organization, and the space required for the transmission organization should be considered for setting.
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. Consider that the support of the pipeline should not be affected when the valve is removed. Usually, the distance between the bracket and the valve's flange should be greater than 300 mm.
3.3 As for large valves, there should be a place to use cranes, or set up hanging columns and hanging beams.
4.
Requirements for installing valves on horizontal pipelines
4.1 The hand wheel of the valve must not face downwards on the horizontal pipeline, except for special technical requirements, and the valve on the pipeline with a risky medium is especially strictly prohibited from facing downwards.
4.2 For the horizontal equipment with rising stem valves, when the valve is open, the valve stem shall not affect the passage, especially when the valve stem is located on the head or knee of the operator.
5.
Other requirements for installing valves
5.1 The base lines of valves placed in parallel on the pipeline should have the same length. When the valves are placed next to each other, the clear distance between the hand wheels should not be less than 100 mm; the valve can also be staggered to reduce the distance between the pipelines.
5.2 For valves that are technically required to be connected to the equipment pipe end, when the nominal diameter, nominal pressure, sealing surface are the same or match the equipment's pipe flange, they should be directly connected to the equipment's pipe end. When the valve is connected to a concave flange, it is necessary to set a convex flange at the corresponding pipe end.
5.3 Except for special technical requirements, the valves on the bottom pipes of towers, reactors, vertical vessels and other equipment shall not be placed in the skirts.
5.4 When the branch pipe is drawn 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.
5.5 The shut off valve of the branch pipe on the pipe gallery is not frequently operated. If there is no permanent ladder, consider reserving space for the use of temporary ladders.
5.6 When the high-pressure valve is open, the generating force is great. It is necessary to set up a bracket to support the valve and reduce the starting stress. The equipment's height should be between 500 and 1200 mm.
5.7 The fire-fighting water valves and steam valves in the equipment boundary area should be dispersedly arranged, and which can be easily obtained by operators in a safe area in the event of an incident.
5.8 The valves of the steam distribution pipe of the heating furnace should be easy to operate, and the distance between the distribution pipe and furnace body should not be less than 7.5 m.
5.9 In the case of valves with threaded connections on the pipeline, there should be joints in the vicinity of the valve to facilitate disassembly.
5.10 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.
5.11 The valve should not bear the applied load to avoid damage to the valve due to excessive stress.
