Hydraulic test of ball tank

How to carry out the hydraulic test of the ball tank?
After the completion of the installation of the ball tank, the pressure test and gas tightness test should be carried out according to the provisions of the drawings.
Pressure test must be set at the top and bottom of the ball tank each with the same range and calibrated pressure gauge.
The range of the selected pressure gauge is about 2 times the test pressure, but should not be less than 1.5 times or more than 4 times the test pressure.
The diameter of the pressure gauge should not be less than 150mm. Test pressure to the top of the ball tank pressure gauge reading shall prevail.
The opening of the ball tank reinforcement ring should be in the pressure test before the passage of 0.4 ~ 0.5MPa compressed air to check the quality of the weld.
Hydraulic test is generally used water, when needed, can also be used will not lead to the occurrence of dangerous other liquids.
The test pressure is as specified in the drawings. The temperature of the liquid during the test should be below its flash or boiling point.
For hydraulic tests on carbon steel, Q345R and normalised 15MnVR steel spherical tanks, the temperature of the liquid shall not be lower than 5°C; for other low alloy steel spherical tanks (excluding low temperature spherical tanks), the temperature of the liquid shall not be lower than 15°C during the hydraulic test. If the steel and plate thickness and other factors caused by the material without ductile transformation temperature increases, it is necessary to correspondingly increase the test liquid temperature.
Test ball tank should be set up at the top of the exhaust port. When filling the liquid, the air in the ball tank should be exhausted. During the test, the outer surface of the spherical tank should be kept dry. During the test, the pressure should be slowly increased to 50% of the test pressure, hold for 15 minutes, then all the welds and connections of the ball tank for penetration inspection, to confirm that there is no leakage and then continue to increase the pressure. When the pressure rises to 90% of the test pressure, hold for 15min and again carry out a leak check to make sure there are no leaks before increasing the pressure. When the pressure rises to the test pressure, hold it for 30min, then reduce the pressure to the design pressure and carry out inspection to make sure there is no leakage. After the hydraulic test is completed, the liquid should be drained and the tank should be blown dry with compressed air. When draining the liquid, it is strictly forbidden to discharge in situ.
Ball tank refilling and liquid discharge process, should be observed in the following processes for the settlement of the foundation:
Before filling the liquid; when filling the liquid to a height of 1/3 of the diameter of the spherical shell; when filling the liquid to a height of 2/3 of the diameter of the spherical shell; after filling the liquid for 24h; after releasing the liquid. The amount of settlement should be measured for each pillar foundation and each pillar foundation should settle evenly. The settlement difference of the foundation shall not be greater than Db/1000 (Db is the diameter of the centre circle of the foundation, mm) after releasing the liquid, and the settlement difference of the adjacent pillar foundation shall not be greater than 2mm.
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