Hydraulic test

1. The hydraulic pressure experiment is an experiment to check the tightness of the pressure-bearing components of the boiler. The scale of the hydraulic pressure experiment should include all the pressure-heating surface system of the boiler, and the steam and water pipes and accessories within the body scale. It is an important measure to ensure the safe operation of the boiler. One.

2. The hydraulic pressure experiment is divided into two types: operating pressure experiment and overpressure experiment. The operating pressure experiment should be carried out at any time according to the requirements of maintenance and inspection. The experimental pressure is the steam pressure at the outlet of the high temperature superheater (5.29Mpa). The overpressure test is generally used for the condition of replacing more pressure-bearing components in the boilers of new equipment and boiler maintenance, and the test pressure is 1.25 times (7.29Mpa) the operating pressure of the drum. The overpressure test and the working pressure water pressure test are generally based on the secondary door. It is forbidden that both the primary door and the secondary door participate in the water pressure experiment.

Steps of water pressure experiment:

1. After the inspection and preparation before the hydraulic test, the boiler can be supplied with water according to the "boiler water supply" rule.

2. After filling up with water, you can slowly increase the pressure when there is no leakage, and the pressure increase speed should be controlled at 0.1 ~ 0.3MPa / min. When the boiler is boosted, it is necessary to use the feed water bypass door to control the pressure. When the pressure rises to When the operating pressure is 10% (0.53Mpa), the pressure increase should be suspended for a comprehensive and detailed inspection.

3. If the condition is outstanding, you can continue to increase the pressure. When approaching the operating pressure, special attention should be paid to the pressure rise speed must be slow and uniform, and to prevent exceeding the operating pressure. When the pressure rises to the operating pressure, the boost is stopped immediately, and the boiler is carried out. Take a full look and watch for pressure drops over 20 minutes. It is assumed that no leakage or wetting of the weld is found during inspection, no residual deformation of the pressure-bearing parts, and the pressure drop within 20 minutes does not exceed 0.2Mpa to be qualified.

4. Assume that the boiler needs to perform the overpressure test, and it should be carried out slowly and evenly after the working pressure test is qualified. Before the overpressure experiment is performed, the safety valve should be “compressed to death”, and the in-situ water level meter should be decommissioned. The inspector can slowly increase the pressure after stopping the operation and returning to the field.

5. When the pressure rises to 1.25 times of the operating pressure, the pressure increase should be suspended, and the time must be maintained for 20 minutes (any inspection is not allowed during this time), and the pressure drop does not exceed 0.2Mpa to qualify.

6. After the experiment is completed, the pressure should be slowly reduced. When the operating pressure is reduced, the inspector can enter the site and check again. After the inspection is completed, the pressure can continue to be reduced.

7. When the pressure drops to 0.1Mpa, open the air valve, restore the "pressed dead" safety valve, put the steam level meter in place, and drain the water to the bottom visible level. (Tell the laboratory staff before discharging the water, if the water quality is qualified, it should be recycled, otherwise drain it.)

8. After the hydraulic pressure test, the test results and problems found in the review should be recorded in the shift record book.

9. Qualified specifications for hydraulic test:

① After 20 minutes of pressure increase to a regular value, the pressure drop does not exceed 0.2Mpa.

② There is no water leakage or wetting in the welded joints of the pressure-bearing parts.

③ There is no trace of residual deformation of the pressure-bearing parts.