All welded ball valve, there is a buried all-welded ball valve, detailing the buried all-welded ball valve installation method:
A: buried all-welded ball valve body buried in the ground, usually with the extension rod way, so open the way on the ground. In the installation before the strict pressure test:
1, the pipeline valve should be installed before the pressure test to ensure that the valve itself is tight and safety.
2, strength test. Strength test using water as a medium; in the valve on both sides of the sleeves welded high pressure - cap cap. The valve open to 45 degrees Celsius position, through the sleeve on the test valve to the ball into the ball valve. Boost to the ball valve nominal pressure of 1.5 times, holding pressure 15min; no leakage for qualified.
3, tightness test. Tightly tested using nitrogen as the medium; the ball valve closed. From the sleeve on the test valve to the ball valve into the nitrogen. The pressure rose to 1.1 times the nominal pressure of the ball valve, the middle chamber pressure valve connected to the water tank containers to detect water. Insert the depth of 1cm; 5min no bubbles produced as qualified.
Second, all-welded ball valve installation:
1, the valve to lift. The valve should be lifted in the correct way. To protect the valve stem, do not connect the chain to the handwheel, gearbox or actuator. The protective cap at both ends of the valve sleeve should not be removed before welding.
2, the valve welding process. Direct Buried Full Welded Ball Valve are connected to the trunk line for welding. Weld quality must meet the "plate welding melting welding joint radiography" (GB3323-2005) Ⅱ level standard, usually a welding and can not fully guarantee all qualified, so when ordering the valve manufacturers should be required at both ends of the valve to increase 1.0m long Sleeves, once the weld is not qualified and have sufficient length to cut the unqualified weld and re-welding in the ball valve and pipe welding, the valve should be in 100% fully open position, so that the ball is splashing the slag damage, while ensuring Valve internal seal temperature does not exceed 140 degrees Celsius, if necessary, can take appropriate cooling measures.
3, the installation of valve wells pouring. Directly buried all-welded ball valve with a special structural design, with maintenance-free features, buried in front of the valve coated with Pu special anti-corrosion coating, while the three were valve seat and stem injection tube, Cavity vent pipes and stem are extended according to the depth of the depth so that the staff can complete the operation on the ground. To achieve a direct buried, the masonry small valve hand can be, and for conventional non-fully welded ball valve can not be buried directly, and the need to build large-scale valve wells, the result is the formation of a dangerous confined space is not conducive to safe operation The At the same time the valve body itself and the valve body and the bolt connection parts of the pipeline will be corrosion, affecting the service life of the valve.
Third, the daily operation and maintenance: In order to extend the life of the valve, usually follow the following procedures to operate and maintain the valve.
1, buried all-welded ball valve operation, the valve often operate both to prevent impurities in the valve seat or ball ball surface aggregation, but also to avoid the valve seat inlaid local wear and tear.
(1) opening and closing time requirements. Excessive valve opening will cause the valve to distort the load too much. Leaving the valve stem damage; too slow switch will lead to a long time the surface of the valve by the media erosion and wear. So the operating time should be kept within a suitable range. According to experience, the valve switch time (seconds) to control the scope of the lower limit of the nominal size of the valve (inch) half, the upper limit of the nominal size of the valve (inch) 5 times to estimate.
(2) the valve is in the state of operation called, the ball should be fully open or fully closed, shall not be in the semi-open or semi-closed position, so as not to damage the valve seat.
2, routine maintenance
The valve seat is the area where the pipeline valve is most likely to be contaminated. In order to ensure freedom of movement of the valve seat, should be cleaned once a year, through the mouth of the valve regularly check the sealing. Auxiliaries of the valve is often very little adjustment, at least once a year to switch and inject the right amount of grease to prevent the ball and the valve seat and the ball between the valve seat and the sub-mill. The good technical characteristics of the buried all-welded ball valve allow the entire gas line to be welded (all welded), enhancing the overall resistance to the pipeline (including the valve), the ability to resist geological hazards (such as geological collapse). Reducing the possibility of leakage. Valve reliability to improve life expectancy, installation and maintenance is also very convenient.