(2) Influence of process conditions on weld formation
1) Influence of weld groove shape and clearance. When other conditions are the same, increasing the groove depth and width will increase the weld penetration, slightly reduce the weld penetration width, and significantly reduce the reinforcement.
2) Effect of flux stack height. The height of flux stack shall ensure that the arc is buried around the wire electrode, generally 25~40mm. When using bonding flux or sintered flux, the flux stack height is 20%~50% higher than that of melting flux from low dry density. The larger the flux stack height, the larger the weld reinforcement and the shallower the penetration.
3) The inclination angle of welding wire, welding nozzle and workpiece also has a greater impact on weld formation. During the welding of all welded pneumatic ball valves, the welding nozzle and welding wire shall be vertical to the surface of the dry workpiece as far as possible.

4、 Precautions for repair and maintenance of pneumatic ball valve:
(1) After running the pipeline system for a period of time, the movable ball valve often suffers from natural loss and some faults, so it is necessary to carry out regular maintenance and overhaul.
(2) Online maintenance of pneumatic ball valve
1. Close the upstream and downstream block valves of the ball valve. Bleed to remove the pressure in the pipeline before and after the ball valve.
2. Keep the pneumatic ball valve fully closed. Remove the startup pipeline.
3. Screw out the screws to remove the pneumatic actuator and driver flange together.
4. Remove the key on the valve rod, unscrew the screw, remove the packing gland and take out the packing.
5. Take out the O-ring from the packing gland.
6. Check the removed parts, repair or replace them if damaged, and clean all parts.
7. Clean and lubricate the sealing surface of stuffing box and O-ring installation groove.
8. Install new packing and new O-ring.
9. Install the packing gland, fasten it with screws, and install the key.
10. Install the pneumatic actuator flange and driver together and fasten them with screws.
11. Connect the pneumatic pipeline and operate the driver to check the opening and closing flexibility of the valve.
12. Install the pipeline and conduct air tightness test according to the pipeline requirements