Fully welded Ball Valve for pipelines should undergo a pressure test before installation to ensure the tightness and safety of the valve itself.
1. Fully welded Ball Valve test
(1) Strength test: The strength test uses water as the medium; high-pressure caps are welded on the sleeves on both sides of the valve. After opening the valve to the 45°C position, inject water into the Ball Valve through the pressure test valve on the sleeve. Increase the pressure to 1.5 times the nominal pressure of the Ball Valve and maintain the pressure for 15 minutes; if there is no leakage, it is qualified.
(2) Tightness test: The tightness test uses nitrogen as the medium; close the Ball Valve. Inject nitrogen into the Ball Valve from the pressure test valve on the sleeve. When the pressure rises to 1.1 times the nominal pressure of the Ball Valve, connect the middle chamber
Pressure Relief Valve to a hose and pass it into the water container for testing. The insertion depth is 1cm; no bubbles are generated within 5 minutes, which is considered qualified.
2. Installation of fully welded Ball Valve for pipelines
(1) Lifting: The valve should be lifted in the correct way. In order to protect the
Valve Stem, do not tie the lifting chain to the handwheel, gearbox or actuator. Do not remove the protective caps at both ends of the valve sleeve before welding.
(2) Welding: The connection between the directly buried fully welded Ball Valve and the main pipeline is welded. The quality of the welds must comply with the Class II standard of "Radiography of Panqu Fusion Welded Joints" (GB3323-2005). Usually one welding cannot completely guarantee that all are qualified, so when ordering valves, the manufacturer should be asked to add 1.0m to both ends of the valve. sleeve, once the weld is unqualified, there is still enough length to cut off the unqualified weld and re-weld it. When welding the Ball Valve and the pipeline, the valve should be in the 100% fully open position to prevent the valve ball from being damaged by splashing welding slag, and at the same time ensure The temperature of the internal seals of the valve does not exceed 140 degrees Celsius, and appropriate cooling measures can be taken if necessary.
