Installation precautions for large welded ball valves

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Large-diameter welded ball valves are important valve products commonly used in industrial production, and their safety is crucial. Improper installation may cause safety issues such as uneven force, which can be harmful to personnel and equipment. It may also cause valve damage, leaks, and other issues, thereby shortening the service life of the valve.

The following are four major aspects to consider when installing these large welded ball valves.

Pipeline inspection

Before installation, it is necessary to ensure that the pre-treatment work of the pipeline has been completed, including cleaning the inside and surrounding areas of the pipeline, removing foreign objects, rust, and other debris.

Valve lifting

When lifting the ball valve, the wire rope should be tied to the lifting ears (rings) or flanges on the valve body and not to the handwheel, valve stem, or actuator to avoid damaging the actuator. During the lifting process, the blind cover sealing on both ends of the ball valve should not be removed to prevent dust and foreign objects from entering the cavity. Avoid hitting the ball valve or knocking the pipeline accessories or joints. Chains should not be used for lifting, and instead, soft belts should be used, with edge protection measures taken to ensure that the ball valve’s external paint is not damaged during the lifting process.

Pre-installation valve inspection

  • Confirm the switch position.
  • Check the installation direction and position.
  • Clean the valve cavity and sealing surface.
  • Check the drive device.

Welding of valves and pipelines

Before welding with the pipeline, the surface of the pipe and the ball valve weld must be cleaned to remove dust, oil, and other impurities to ensure the quality and strength of the welds.

The dimensions and positional tolerance of the ball valve piping should be within the allowable range and consistent with the centerline of the main pipe before welding. Before welding, cover the valve sealing surface area with a protective tape about 25mm wide to prevent spatter from falling into these areas.

During welding, the corresponding welding process should be operated according to the appropriate welding process specification, selecting suitable welding techniques and parameters such as preheating temperature, welding current, and welding speed to ensure welding strength and quality.

Large-diameter valves should be welded in sections in a certain order to ensure welding quality and strength.