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How to properly install the valve in the high pressure steam pipe

Update:10-06-2019
Summary:

The high-pressure steam pipe installation valve is gene […]

The high-pressure steam pipe installation valve is generally welded, and the argon arc welding is generally used for the bottom cover welding. High pressure and steam must strictly guarantee the safety of the pressure and the safety of the seal. Therefore, many welding shut-off valves are widely used in thermal power plants.

Before installing the valve in the high-pressure steam pipeline, the inner and outer surfaces of the pipe fittings shall be inspected. The quality of the pipe shall not be lower than the relevant national standards. The pipe valve must have the quality certificate of the manufacturer and all the high-pressure steam pipes. The inspection and approval shall be carried out to the supervision department in a timely manner. In addition, the valves used in high pressure steam lines must be tested for pressure strength and stringency.

When the high-pressure steam pipe is installed, the surface of the welding groove of the high-pressure steam pipe should be smooth, free of cracks, no heavy skin, no barb, no unevenness, no slag, no oxide, no iron cutting, etc. The slope of the end face shall not be greater than one percent of the outer diameter of the pipe and shall not exceed 3 mm.

For the installation weld of high-pressure steam pipe, the visual inspection must be carried out. The width of the weld should be 2mm beyond the edge of the groove. The height of the weld bead should conform to the design regulations. The shape should be smooth and the surface should not have cracks. Defects such as stomata and slag inclusions shall not be more than 0.5 mm. After the appearance inspection of the high-pressure steam pipeline is qualified, it shall be carried out according to the specifications or design drawings. In addition, the high-pressure steam pipe welds should be 100% radiographic inspection, the quality level should not be lower than II, the inspection of unqualified welds should be repaired and repaired, and repair welding and repair welding are prohibited.

The pipe supports and hangers of the high-pressure steam pipe installation valve have two forms: fixed bracket and sliding bracket. The fixed branch and hanger must be installed according to the design requirements and should be fixed before the compensator is pre-stretched. When sliding brackets and hangers are installed, the sliding surface shall be clean and flat, and there shall be no skew or jamming. The installation position should be offset from the center of the support and the surface to the opposite direction of the displacement, and the offset should be one-half of the thermal displacement value of the high-pressure steam pipeline.

The high pressure steam pipe compensation device mainly has various types of compensators. It should be pre-stretched according to the thermal displacement value of the high pressure steam pipe before installation.

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