The electric ball valve mainly depends on the pipe to play the role of expansion and contraction. The function and strength design of the electric ball valve is mainly the design of the pipe. Different designs and combinations of pipes can make the pipe stretch, compress or bend, thus forming three basic forms of electric ball valve: axial, transverse and angular
1. The size and technical requirements of the connecting flange and end pipe of the electric ball valve and the pipeline shall comply with the corresponding standard end pipe connection, and the pipe orifices at both ends shall be provided with a 30 degree+/- 2.5 degree groove.
2. When the end pipe of the electric ball valve is rolled steel welded pipe, the perimeter tolerance and roundness tolerance of the external end of the end pipe shall comply with relevant regulations.
3. Circumferential welds connecting pipes and end pipes shall be welded by argon tungsten arc welding or consumable electrode arc welding. When the wall thickness of a single layer of pipe is greater than 2mm, electric arc welding can be used.
4. When assembling the electric ball valve, protective measures shall be taken for the pipe to prevent welding arc burning through the pipe and welding slag splashing on the pipe. The welds of each part of the electric ball valve shall be free of cracks, pores, slag inclusions and other defects, and the undercut depth shall not be greater than 0.5mm.
5. The appearance and geometric dimensions of the electric ball valve shall be inspected after assembly and welding. Coaxiality tolerance of both ends of electric ball valve: 5mm when the nominal diameter is less than or equal to 500mm; When the nominal diameter is greater than 500mm, it is 1% of the nominal diameter and less than or equal to 10mm. The perpendicularity tolerance between the two end faces of the electric ball valve and the main axis shall be 1% of the nominal diameter and less than or equal to 3mm. If the electric ball valve is pre stretched before delivery, the factory length tolerance after pre stretching shall also meet the requirements. The free state length of the electric ball valve and the factory length after pre stretching shall be inspected respectively.
6. After the pressure bearing weld of the electric ball valve is welded, the pressure test shall be carried out on the pressure bearing weld, and the test pressure shall be 1.5 times of the design pressure. According to the volume of the electric ball valve, hold the pressure for 10~30min, check whether there is leakage at each part of the electric ball valve, and the ratio of the wave distance under pressure to the wave distance before pressure shall not exceed 1.15.