OPERATION SPECIFICATION FOR FLANGE AND VALVE CONNECTION INSTALLATION

 The operation organization of the valve is best placed at 1.2m away from the operating ground, which will be in line with the chest. When the base of the valve exceeds 1.8m above the operating ground from the handwheel, the more operated valves and safety valves should be provided with the operating way. For pipelines with more valves, the valves should concentrate on the way as far as possible for easy operation.

 

1. Flange surfaces of valves and piping shall be undamaged, scratched, and kept clean. Especially when using metal gaskets (elliptical or octagonal cross-section), the grooves of flange should be consistent with gaskets, and red lead should be applied to match the flange to ensure its good sealing condition.

 

2. The verticality of the flange surface on the piping and the center line of the piping and the error of the bolt hole of the flange should be within the allowable range. Valves and piping centerlines should be aligned before installation.

3. When connecting two flanges, first of all, the sealing surface of flange and gasket should be compressed evenly, so that the flange can be connected by the same bolt stress.

 

4. When tightening bolts, wrenches matching nuts should be used. When tightening bolts with hydraulic and pneumatic tools, the injection should exceed the specified moment.

 

5. Flange fastening should avoid uneven force, and should be tightened in symmetrical and intersectional order.

 

6. After installation of flange, make sure that all bolts and nuts are firm and even.

 

7. The material of bolts and nuts must conform to the regulations. After tightening, it is advisable for the bolt head to expose two pitches from the nut.

 

8. Fastening bolts and threads. In order to prevent loosening caused by vibration, gaskets should be used. In order to avoid adhesion between threads during tempering, anti-adhesion agent (molybdenum disulfide) should be applied to the threads during installation.

 

9. For high temperature valves above 300 degrees Celsius, flange connecting bolts, cap fastening bolts, pressure sealing bolts and packing cap bolts must be tightened again after the temperature rises.

 

10. Low temperature valves are installed at atmospheric temperature. In practical application, when the medium passes through, it becomes a low temperature state. Flanges, gaskets, bolts and nuts will shrink due to the formation of temperature difference, and because the materials of these parts are different, their linear expansion coefficients are also different, forming a very leaky environmental condition. From this objective situation, when fastening bolts at high temperature, it is necessary to adopt the moment which takes into account the shrinkage factors of components at low temperature.

Valve equipment shall be in accordance with the valve operation instructions and relevant regulations. Careful inspection and careful construction should be carried out during the construction process. Before valve equipment, the equipment should be carried out after qualified pressure test, carefully check whether the specifications and types of valves are in accordance with the drawings, check whether all parts of the valves are flawless, whether the opening and closing valves are rolling sensitively and freely, whether the sealing surface is harmful, and so on. After admitting correctness, the equipment can be carried out.