Valve installation requirements

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

The valve shall be installed in accordance with the valve operation manual and relevant regulations. In the process of construction, careful inspection and construction shall be carried out. Before the installation of the valve, the installation shall be conducted after the pressure test is qualified. Carefully check whether the specification and model of the valve are consistent with the drawing, check whether all parts of the valve are in good condition, whether the opening and closing valve can rotate freely, whether the sealing surface is damaged, etc. after confirmation, the installation can be conducted.

When the valve is installed, the operating mechanism of the valve should be about 1.2m away from the operating ground, which should be flush with the chest. When the center of the valve and the handwheel are more than 1.8m away from the operation ground, the operation platform shall be set for the valve and safety valve with more operation. For pipelines with many valves, the valves shall be concentrated on the platform as much as possible for easy operation.

For single valve over 1.8m and infrequently operated, equipment such as chain wheel, extension rod, movable platform and movable ladder can be used. When the valve is installed below the operation surface, the extension rod shall be set, and the ground valve shall be set with the ground well. For the sake of safety, the ground well shall be capped.

For the valve stem on the horizontal pipeline, it is better to vertically upward, rather than downward installation of the valve stem. The valve stem is installed downward, which is inconvenient for operation and maintenance, and easy to corrode the valve. The landing valve shall not be installed askew to avoid inconvenient operation.

The valves on the side-by-side pipeline shall have space for operation, maintenance and disassembly. The clear distance between the handwheels shall not be less than 100mm. If the pipe distance is narrow, the valves shall be staggered.

For valves with large opening force, low strength, high brittleness and heavy weight, valve support valve shall be set before installation to reduce starting stress.

When installing the valve, pipe tongs shall be used for the pipes close to the valve, while ordinary spanners shall be used for the valve itself. At the same time, during installation, the valve shall be in a semi closed state to prevent rotation and deformation of the valve.

The correct installation of the valve shall make the internal structure form conform to the flow direction of the medium, and the installation form conform 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 according to the requirements of process pipeline. The arrangement of the valve shall be convenient and reasonable, and the operator shall be easy to access the valve. For the lift stem valve, the operating space shall be reserved, and the valve stem of all valves shall be installed upward as far as possible and perpendicular to the pipeline.

Installation of valve connection surface

When installing the valve with thread connection at the end, the depth of thread into the valve shall be appropriate. If the thread is screwed into the valve seat too deep, it will affect the good matching between the valve seat and the ram. If it is screwed into too shallow, it will affect the sealing reliability of the joint, and it is easy to introduce leakage. At the same time, the thread sealing material should be Teflon raw tape cargo sealant, pay attention not to give the sealing material to the valve cavity.

For the valve with flange end connection, the connection surface of the flange shall be aligned first, the cover shall be vertical to the pipeline, and the bolt hole shall be aligned. The valve flange shall be parallel to the pipeline flange, the flange clearance shall be moderate, and there shall be no staggering, tilting and other phenomena. The center gasket between the flanges shall be placed in the center without skewing, and the bolts shall be tightened symmetrically and evenly. Prevent forced connection and tightening during valve installation, and generate an additional residual force.

Before installation, thoroughly remove the dirt on the inner wall and external thread of the pipe; remove the burrs and foreign matters that hinder the medium flow and may affect the operation of the equipment, and blow out the dirt, slag and other sundries in the pipe before connecting the pipe. Prevent damaging the sealing surface of the valve or blocking the valve.

When installing the connecting valve at the welding end, the welding joint at both ends of the valve shall be assembled and spot welded first, then the valve shall be opened, and then the welding seam shall be welded according to the welding process card. After welding, the weld appearance and internal weld quality shall be inspected to ensure that there is no air hole, slag inclusion, crack, etc. if necessary, the weld seam shall be subject to line shooting or over control inspection

Installation of heavy valve

When installing the heavy valve (DN > 100), use lifting tools or equipment, and the lifting rope shall be tied on the flange or bracket of the valve, not on the handle type stem of the valve, so as to avoid damage to the valve.