Installation requirements for valves

The quality of valve installation directly affects the use of valves in the future. Therefore, construction units and production units should attach great importance to it.

Installation of valves shall be carried out in accordance with the instructions for the use of valves and relevant regulations. In the process of construction, careful inspection and meticulous construction should be carried out. Before installation, the valve should be installed after qualified pressure test. Carefully check whether the specifications and models of the valve are in accordance with the drawings, check whether the parts of the valve are intact, whether the opening and closing valves are flexible, whether the sealing surface is damaged, etc. After confirmation, the valve can be installed.

When the valve is installed, the operating mechanism of the valve should be about 1.2m away from the operating ground, which will be in line with the chest. When the center of the valve and the handwheel are more than 1.8m away from the operating ground, the operating platform should be set for the more operated valves and safety valves. Pipeline with more valves, the valves are concentrated on the platform as far as possible for easy operation.

For single valves over 1.8m and not frequently operated, sprockets, extension rods, movable platforms and movable ladders can be used. When the valve is installed below the operating surface, the elongation rod should be set, and the ground valve should be set up with the ground well. For safety, the ground well should be covered.

The valve stem of the valve on the horizontal pipeline should be vertical upward rather than downward installed. Stem downward installation, inconvenient operation, inconvenient maintenance, but also easy to corrode the valve accident. Do not install the landing valve askew to avoid inconvenience in operation.

Valves on side-by-side pipelines shall have vacancies for operation, maintenance and disassembly. The net distance between handwheels shall not be less than 100 mm. If the pipe spacing is narrow, the valves shall be staggered and arranged.

For valves with large opening force, low strength, high brittleness and heavy weight, support valves should be set before installation to reduce start-up stress.

When installing valves, pipe pliers are used for pipes close to the valves, while common wrenches are used for the valves themselves. At the same time, during installation, the valve should be in a semi-closed state to prevent the valve from rotating and deforming.

Correct installation of the valve should make the internal structure conform to the flow direction of the medium, and the installation conforms to the special requirements and operation requirements of the valve structure. In particular, it should be noted that valves with medium flow direction requirements should be installed in accordance with the requirements of process pipelines. The arrangement of valves should be convenient and reasonable. Operators are easy to access the valves. For lifting stem valves, the operating space should be set aside. The stem of all valves should be installed upwards and perpendicular to the pipeline as far as possible.

Installation of Valve Connection Surface

Valves with threaded connections at the installation end should be properly screwed into the depth of the valve. Thread screwed into the valve seat with too deep pressure will affect the good fit of the valve seat and gate plate. Too shallow screwing will affect the sealing reliability of the joint and lead to leakage easily. At the same time, the thread sealing material should be tetrafluoroethylene raw tape cargo sealant, pay attention not to the sealing material to the valve chamber.

For valves connected at the end of flange, the connection surface of flange should be aligned first, the cover is perpendicular to the pipeline, and the bolt hole should be aligned. Valve flange should be parallel to pipeline flange. Flange clearance should be moderate. No misalignment or inclination should occur. The center gasket between flanges should be placed in the center, not deflected, and the bolts should be tightened symmetrically and evenly. Prevent forced connection tightening during valve installation, resulting in an additional residual force.

Before installation, the dirt on the inner wall and external threads of the pipe should be thoroughly removed; burrs and foreign bodies that hinder the flow of medium and may affect the operation of the equipment should be removed; dirt, slag and other debris in the pipe should be blown off before connection. Prevent damaging the sealing surface of the valve or blocking the valve.

Installation of welded end connecting valves should first group the weld joints at both ends of the valve after spot welding, open the valve, and then apply welding seam according to welding process. After welding, the appearance and internal quality of the weld seam should be checked to ensure that there are no gas holes, slag inclusion, cracks, etc. Radiation or over-control inspection should be carried out on the weld seam when necessary.

Installation of Heavy Valves

When installing heavy valves (DN > 100), using lifting tools or equipment, the lifting rope should be tied to the flange or bracket of the valve, and should not be tied to the handle stem of the valve in order to avoid damaging the valve.

What are the general requirements for valve installation?

The General requirements for valve installation, the most suitable installation height, the direction of valve and stem on horizontal pipeline are as follows:

(1) Valves should be located in easy access, easy operation and maintenance. Valves on rows of pipes (e.g. pipes for inlet and outlet devices) should be centrally arranged, and operation platforms and ladders should be considered. Valves on parallel pipelines should be aligned as far as possible. The net distance between handwheels should not be less than 10Qmm. In order to reduce the pipe spacing, the valve can be staggered.

(2) The installation position of the valve which is often operated should be easy to operate. The most suitable installation height is 1.2m from the operating surface. When the height of the valve handwheel center exceeds 2 m of the operating surface, platforms should be set for centrally arranged valves or individual valves and safety valves with frequent operation, and appropriate measures should be taken for individual valves with infrequent operation (such as sprockets, extension rods, movable platforms and movable ladders). Chains of sprockets should not hinder passage. Valves on pipes and equipment of dangerous media shall not be installed within the height range of the head of a person in order to avoid touching the head of a person or directly injuring the face of a person when the valve leaks.

(3) Valves for partitioning equipment should be directly connected to or close to the equipment nozzle. Valves on pipelines connected to equipment with extremely hazardous and highly hazardous toxic media.