Hydraulic test of the spherical tank

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1. After the installation of the spherical tank is completed, pressure tests and airtightness tests shall be carried out in accordance with the specifications in the drawings. II. During the pressure test, a pressure gauge with the same range and calibrated properly must be installed at both the top and bottom of the spherical tank. It is advisable to choose a pressure gauge with a range of about 2 times the test pressure, but it should not be less than 1.5 times or more than 3 times the test pressure. It is advisable that the diameter of the pressure gauge be no less than 150 mm. The test pressure is based on the reading of the pressure gauge at the top of the spherical tank. III. Before the pressure test, compressed air at a pressure of 0.4~0.5 MPa should be introduced into the opening reinforcement rings of the spherical tank to check the quality of the welds. IV. Hydrostatic Test 1. Water is generally used for hydrostatic tests; other liquids that do not pose a risk can also be used if necessary. 2. The test pressure shall comply with the provisions of Article 3.11.2 of GB 12337-2014. 3. Test temperature: (1) The temperature of the liquid during testing should be below its flash point or boiling point. (2) When conducting hydraulic tests on spherical tanks made of Q345R, Q370R, and 07MnMoVR, the liquid temperature must not be lower than 5℃ ； When conducting hydraulic tests on Q245R and other low-alloy steel spherical tanks, the liquid temperature must not be lower than 15°C. If factors such as plate thickness cause the material’s plastic transition temperature to increase, the testing temperature must be raised. 4. Test requirements: (1) An exhaust port should be provided at the top of the spherical tank during testing. The air inside the spherical tank must be exhausted when filling it. During the test, the outer surface of the spherical tank should be kept dry. (2) During the test, the pressure should be increased gradually; once it reaches 50% of the test pressure, it should be held at that level for 15 minutes. Afterward, a leak check should be conducted on all the welds and connections of the spherical tank, and only after confirming no leaks are present should the pressure be increased further. (3) When the pressure rises to the design pressure, hold it for 10 minutes, then conduct another leak check; only after confirming no leaks are present should the pressure be increased further. (4) When the pressure rises to the test pressure, hold it for 30 minutes, then reduce the pressure to the design pressure and conduct an inspection; no leakage is considered acceptable. (5) After the hydraulic test is completed, the liquid should be drained, and the tank should be dried out using compressed air. During drainage, it is strictly prohibited to discharge directly on site. 5. Requirements for foundation settlement; (1) During the process of filling and draining the spherical tank, the settlement of the foundation should be monitored at the following stages: before filling ； When the liquid level reaches 1/3 of the sphere shell diameter ； When the liquid level reaches 2/3 of the sphere shell diameter ； After 24 hours of being filled with liquid ； After draining the liquid. (2) The settlement of each pillar foundation should be measured, and the foundations of all pillars should settle evenly. After fluid drainage, the differential settlement of the foundation shall not exceed Db/1000 (where Db is the diameter of the base circle, in mm), and the differential settlement between adjacent pillar foundations shall not exceed 2 mm. When exceeded, measures should be taken to address it.