Preparation before installation

Check the ball valve and related accessories

Appearance inspection: Check the surface of the ball valve body, stem, seat and other components for cracks, sand holes, scratches, rust and other defects. The sealing surface of the valve body connecting flange should be flat and smooth, without radial grooves or other damages that may affect the sealing. For example, if deep scratches are found on the surface of the valve body, it may cause medium leakage during use, affecting the normal sealing performance of the ball valve.

Specification verification: Carefully verify whether the model and specifications of the ball valve (such as nominal diameter, nominal pressure, connection method, etc.) are consistent with the design requirements. At the same time, check whether the material of the ball valve meets the characteristics of the medium used. For example, when transporting corrosive media, the material of the ball valve should have corresponding corrosion resistance. For example, for media containing hydrochloric acid, stainless steel ball valves are usually used.

Accessory integrity check: Confirm that the bolts, nuts, washers, and other accessories required for the installation of the ball valve are complete and free from damage, deformation, and other conditions. The material and specifications of the gasket should match the working pressure, temperature, and medium properties of the ball valve.

Prepare installation tools and site

Tool preparation: Prepare corresponding installation tools according to the specifications and installation method of the ball valve, such as wrenches, screwdrivers, pipe clamps, torque wrenches, etc. For large ball valves, lifting equipment (such as cranes, hoists, etc.) may also be required to assist in installation.

Site cleaning: Clean up the installation site to ensure that there are no debris or obstacles around the installation location, the ground is flat and solid, and it is convenient for operators to carry out construction and equipment lifting. If the installation environment contains moisture, corrosive gases, etc., corresponding protective measures should be taken, such as building temporary protective shelters, using anti-corrosion materials, etc., to protect the ball valve and installation tools.

Pipeline pretreatment

Pipeline cutting and groove processing

Cutting: According to the design requirements, use suitable cutting tools (such as cutting machines, saws, etc.) to cut the pipeline, ensuring that the cutting end face is flat and perpendicular to the pipeline axis, with a deviation generally not exceeding 1% of the pipeline diameter and a maximum of 3mm. For example, for DN100 pipelines, the perpendicularity deviation between the cutting end face and the pipeline axis should be controlled within 1mm.

Groove processing: According to the material and welding process requirements of the pipeline, perform groove processing on the end of the pipeline. The form and size of the groove should comply with the relevant standards (such as GB/T 985.1-2008 "Recommended Groove for Gas Welding, Shielded Arc Welding, Gas Shielded Welding, and High Energy Beam Welding"). After groove processing, impurities such as oxide scale, oil stains, and slag on the surface of the groove should be removed to expose the metallic luster.

Pipeline alignment and fixation

Alignment: Pre assemble the ball valve with the pipeline, adjust the position of the pipeline so that the flange faces (or other connecting end faces) at both ends of the ball valve are parallel and aligned with the flange faces (or connecting end faces) of the pipeline, and the deviation should meet the relevant standard requirements. When connecting flanges, the parallelism deviation between flange faces should not exceed 1.5/1000 of the flange outer diameter and not exceed 2mm; the center deviation of flange bolt holes should not exceed 5% of the aperture.

Fixed: Use temporary supports or fixtures to securely fix the pipes and ball valves to prevent displacement during subsequent installation. For large-diameter pipelines and ball valves, multiple support points should be set up to ensure the stability of the pipelines and ball valves.

Ball valve installation

Installation of flange connected ball valve

Gasket installation: Place a suitable gasket on the flange sealing surface of the ball valve and pipeline. The gasket should be placed flat, without deviation, wrinkles, or other phenomena. For metal wound gaskets, it should be noted that the winding direction should be consistent with the direction of the medium flow.

Bolt connection: Thread the bolts through the bolt holes of the ball valve and pipeline flange in sequence, and fit them with nuts. Tighten the nut by hand to make initial contact between the gasket and the flange sealing surface. Then use a torque wrench to tighten the nut symmetrically and evenly according to the specified torque value. The torque value should be determined based on the specifications, materials, and relevant standards of the bolt. For example, for M16 grade 8.8 bolts, the tightening torque may be between 200-300N · m under normal operating conditions. During the tightening process, it should be done 2-3 times, gradually reaching the specified torque value to avoid uneven stress on the gasket or flange deformation caused by one-time tightening.

Welding connection ball valve installation

Spot welding fixation: After aligning and fixing the ball valve with the pipeline, perform spot welding fixation first. The spot welding positions should be evenly distributed on the circumference of the pipeline, generally not less than 3 points. The length of spot welding should not be too long, usually 10-20mm, to prevent displacement of the ball valve during the welding process.

Welding construction: Select appropriate welding processes and materials based on the materials of the pipeline and ball valve. Symmetrical and segmented welding should be adopted during welding to reduce welding deformation. During the welding process, parameters such as welding current, voltage, and welding speed should be controlled to ensure the quality of the weld seam. After welding is completed, the weld seam should undergo visual inspection and non-destructive testing (such as radiographic testing, ultrasonic testing, etc.) to ensure that the weld seam is free of defects such as cracks, pores, slag inclusions, etc.

Installation of ball valves with other connection methods

Threaded connection: Apply an appropriate amount of sealant (such as polytetrafluoroethylene sealant) on the threaded surface of the ball valve and pipeline, and then slowly screw the ball valve into the pipeline thread. During the tightening process, a suitable wrench should be used to avoid damaging the threads due to excessive force. After tightening, the connection should be checked for good sealing and no leakage.

Clamp connection: Insert the connection ends of the ball valve and pipeline into the clamps respectively, and ensure that the insertion depth meets the requirements. Then install the sealing ring of the clamp and tighten the bolt of the clamp to ensure a tight fit between the sealing ring and the connecting end face, achieving a sealing effect. When tightening bolts, the operation should be carried out according to the specified torque value to ensure a firm and reliable connection.

Post installation inspection and debugging

Appearance inspection: Check again whether the installation position of the ball valve is correct, whether the connection parts are firm, and whether there are any looseness, deformation, etc. At the same time, check whether the operating components of the ball valve (such as the handle, gearbox, etc.) are flexible and whether there is any jamming phenomenon.

leakage test

Strength test: For ball valves with a nominal pressure PN ≤ 1.6MPa, the test pressure is 1.5 times the nominal pressure; For ball valves with a nominal pressure PN>1.6MPa, the test pressure is 1.25 times the nominal pressure. The test medium is generally clean water, and the test time is 5 minutes. During the experiment, observe whether there are any leaks, deformations, or other phenomena in the valve body and connecting parts of the ball valve.

Tightness test: The test pressure is the nominal pressure of the ball valve, and the test medium is also clean water. For bi-directional sealed ball valves, separate tests should be conducted in both directions. The test time is the specified minimum holding time (determined according to the specifications and relevant standards of the ball valve, generally 1-5 minutes), and the sealing surface of the ball valve is checked for any leakage.

Operation and debugging: After confirming the good sealing of the ball valve, perform operation and debugging on the ball valve. Manually operate the ball valve and check whether its opening and closing are flexible and in place, and whether the opening and closing time meets the design requirements. For ball valves with electric, pneumatic and other driving methods, it is also necessary to check whether the driving device is operating normally and whether the limit switch is accurate and reliable. During the debugging process, the operating parameters of the ball valve, such as opening torque, closing torque, etc., should be recorded for subsequent maintenance and repair.

Precautions for ball valve installation

Installation environment aspect

Temperature and humidity: Avoid installing ball valves in environments with excessively high or low temperatures, as extreme temperatures may affect the material properties and sealing effectiveness of the ball valves. For example, in low-temperature environments, the sealing material of ball valves may become hard and brittle, leading to a decrease in sealing performance; In high temperature environments, components of ball valves may become stuck due to thermal expansion. At the same time, the humidity of the installation environment should not be too high, as excessive humidity may cause rusting and corrosion inside the ball valve, affecting its service life. Generally speaking, the temperature of the installation environment should be between -20 ℃ and+60 ℃, and the relative humidity should not exceed 85%.

Corrosive media: If there are corrosive media (such as acid, alkali, salt, etc.) in the installation environment, corresponding protective measures should be taken. For example, applying anti-corrosion coating to ball valves, selecting materials with better corrosion resistance, or installing ball valves in sealed protective boxes to prevent corrosive media from damaging the ball valves.

Vibration and shock: Avoid installing ball valves in places with high vibration and shock, such as near large motors, compressors, and other equipment. Vibration and impact may cause loosening, wear, and even damage to the components of the ball valve, affecting its normal operation. If unavoidable, vibration reduction measures should be taken, such as installing vibration reduction pads, vibration reduction brackets, etc.

Installation operation aspect

Avoid forced installation: During the installation process, it is strictly prohibited to use strong force (such as hammering, twisting, etc.) to connect the ball valve to the pipeline, in order to avoid damaging the components of the ball valve or affecting its sealing performance. If installation difficulties are encountered, check whether the size and tolerance of the ball valve and pipeline meet the requirements, or whether there are foreign objects blocking, etc., and promptly eliminate the fault before installation.

Pay attention to installation direction: For ball valves with flow requirements (such as globe valve ball valves), they must be installed correctly according to the flow direction of the medium, otherwise it may cause the ball valve to malfunction or reduce its sealing performance. Before installation, carefully check the flow direction markings on the ball valve to ensure that the installation direction is correct.

Preventing foreign objects from entering: During installation, measures should be taken to prevent debris (such as welding slag, iron filings, dust, etc.) from entering the interior of the ball valve. Temporary blind plates or filters can be installed at the inlet and outlet of the ball valve. After installation, they can be removed before the system pressure test. If foreign objects enter the interior of the ball valve, they may jam the ball or damage the sealing surface, causing the ball valve to leak or malfunction.

Maintenance and upkeep aspects

Cleaning after installation: After the installation of the ball valve is completed, its surface should be cleaned to remove impurities such as oil and dust that have been contaminated during the installation process. You can use a clean cloth dipped in an appropriate amount of cleaning agent to wipe, but be careful not to corrode the material of the ball valve with the cleaning agent.

Regular inspection: After the ball valve is put into use, it should be inspected regularly, including the sealing performance, operational flexibility, and fastening of the connection parts. It is generally recommended to conduct a routine inspection every 3-6 months. For ball valves that are frequently used or in harsh working conditions, the inspection cycle should be appropriately shortened.

Lubrication and maintenance: According to the user manual of the ball valve, regularly lubricate and maintain the operating components of the ball valve (such as the valve stem, gearbox, etc.). Choose the appropriate lubricant and operate according to the prescribed lubrication cycle and method to reduce wear between components and extend the service life of the ball valve.

Personnel safety aspect

Operation training: Installation personnel should receive professional training, familiarize themselves with the installation process, operation methods, and safety precautions of ball valves. Untrained personnel are not allowed to install ball valves without authorization to avoid safety accidents.

Safety protection: During the installation process, the installation personnel should wear necessary safety protection equipment, such as safety helmets, safety shoes, gloves, etc. For high-altitude operations, safety belts should also be fastened to ensure personal safety. At the same time, when operating ball valves with electric, pneumatic and other driving methods, relevant electrical and pneumatic safety regulations should be followed to prevent accidents such as electric shock and mechanical injury.