Buried all-welded ball valves are widely used in various fields, its excellent quality and high-performance stability is ordinary cast steel ball valves can not be achieved, full-weld ball valve service life is much greater than cast steel ball valves, all-welded ball valves are widely used in urban gas, urban heating, petrochemical, shipbuilding, steel, pressure control stations, power plants and other types of pipeline equipment.
Buried all-weld ball valve buried full-weld ball valve installation 1, buried all-weld ball valve installation before the test pressure pipeline valve should be installed before the pressure test, to ensure the tightness and safety of the valve itself.
(1) intensity test.
strength test using water as a medium, welding high pressure - aggressive cap on the sleeve tubes on both sides of the valve. After opening the valve to a position of 45 degrees Celsius, water is injected into the ball valve through the test pressure valve on the sleeve tube. Boost to 1.5 times the pressure of the ball valve, maintain 15min;
(2) rigorous test.
test uses nitrogen as a medium and closes the ball valve. The pressure valve is tested from the sleeve tube and nitrogen is injected into the ball valve. The pressure rises to 1.1 times the official pressure of the ball valve, and the medium cavity pressure valve is connected to the hose to pass through the water container for testing. The insertion depth is 1cm;
2, buried full welding ball valve installation (1) lifting.
the valve should be hoisted in the correct manner and do not tie the chain to the hand wheel, gearbox or actitor in order to protect the stem.
the protective caps at both ends of the valve sleeves should not be removed before welding. (2) Welding. The connection between the straight - buried fully welded ball valve and the trunk line is welded. Weld quality must comply with the "pan-bending welding welding joint ray photo" (GB3323-2005) II. Grade plate standards, usually a welding can not fully guarantee full eligibility, so when ordering valves should require manufacturers to add 1.0m long-sleeved tubes at both ends of the valve Once the weld is not qualified and there is sufficient length to cut off and re-weld the non-conforming weld in the ball valve and pipe welding, the valve should be in the full open position, so as to avoid damage to the ball by the splashing solder slag, while ensuring that the internal seal temperature of the valve does not exceed 140 degrees Celsius, if necessary, appropriate cooling measures can be taken. (3) Valve well masonry.
Buried full welding ball valve using a special structural design, with maintenance-free features, buried before the outside of the valve coated with Pu special anti-corrosion coating, while the three valve seat and stem emergency grease injection tube, cavity empty pipe and stem according to the depth of the proper extension, so that staff on the ground can complete the operation. After the direct burial is achieved, a small valve hand well can be built, as shown in Figure 4.
for conventional non-full welding ball valves can not be directly buried, and the need to build large valve wells, but the result is a dangerous confined space, not conducive to safe operation.
at the same time the valve body itself and the bolted connection between the valve body and the pipe will be corroded, affecting the service life of the valve.
buried all-weld ball valve maintenance and maintenance 1, buried all-welded ball valve operation valve often operation can not only prevent impurities in the valve seat or valve ball surface accumulation, but also avoid the seat inset local excessive wear. (1) Opening and closing time requirements.
valve switch too fast will cause the valve to twist too much load. The valve stem is damaged, and the switch is too slow, which will cause the seat surface to wear out by the media for a long time. The operation time should therefore be kept within a suitable range. As a rule of law, the switching time (seconds) of the valve controls the range, the lower limit can be estimated by half of the valve's official size (inches) and the upper limit by 5 times the valve's official size (inches). (2) valve in the delivery state called, valve ball should be in full open or full off, not in the half-open or half-off position, so as to avoid seat damage.
2, buried all-weld ball valve daily maintenance seat cavity is the pipeline valve easy to be contaminated area. In order to ensure the freedom of movement of the seat, should be cleaned once a year, the well through the sewage nozzle regularly check the sealing of the valve. The valves of the auxiliary gas trunks are often rarely adjusted, and should be switched on and off less once a year and injected with the appropriate amount of grease to prevent the sphere and seat bonding and the sub-grinding between the valve ball and the seat.
the good technical characteristics of the buried all-welded ball valve make the whole pipeline waved together (all welded), and enhanced the overall resistance of the pipe (including valves) to stress, resistance to geological disasters (such as geological collapse). Reduces the possibility of air leakage. Valve reliability increases life and is easy to install and maintain.