Specific definition of the hydrotest pressure in the standards
Thread Content
GB150.1 4.6.1.6 Pressure vessels under external pressure shall be subjected to a pressure test using internal pressure, with the test pressure in accordance with the provisions of 4.6.2.3. 4.6.2.3 Hydrostatic test for externally pressurized vessels: Test pressure = 1.25 times the design pressure. One of the containers I have here has a jacket; the design pressure for its inner cylinder is -0.1/0.35, the design temperature is 148°C, and the material used is S31603 ； The jacket’s design pressure is 0.4, the design temperature is 152°C, and the material used is S30408. Based on these specifications, should the actual design negative pressure for the inner cylinder be (-0.1) – 0.4 = -0.5? The hydrostatic test pressure would then be 1.25 * 0.5 = 0.6. I’m not sure if this understanding is correct
According to the above regulations, the actual designed negative pressure of the inner cylinder is -0.1 MPa, while the designed pressure of the jacket is 0.4 MPa. The hydrostatic test pressure is 1.25 times the design pressure; therefore, the hydrostatic test pressure for the inner cylinder is 1.25 * (-0.1) MPa = -0.125 MPa. Please note that the hydrotest pressure cannot be a negative value; therefore, in this case, the hydrotest pressure should be set to 0. .
You’re probably working in the pharmaceutical industry. First, you need to determine whether there will be any operating conditions where positive pressure exists inside the clamping sleeve despite the presence of internal or negative pressure. Based on the most severe operating conditions, rather than the literally maximum ones. The pharmaceutical industry experiences negative pressure during steam sterilization, and at this time the jacket usually does not function. If the device encounters the kind of operating conditions you mentioned, then proceed according to your understanding.
The container is pressure-tested separately, independent of the design pressure of the jacket
Does no one look at the blueprints? The requirements on the drawings are more than you think.
1. Pressure tests include hydraulic tests, pneumatic tests, and combined gas-liquid tests. Hydraulic tests generally use water as the test medium; there is no such term as “hydrostatic test” in the technical nomenclature； 2. For the pressure test, you calculate the test pressure using either the design pressure or the maximum allowable operating pressure (the pressure approved for use at reduced levels). The issue you mentioned is something that needs to be taken into consideration during the design process ； 3.-0.10 MPa is not within the range of GB/T150-2011 ； 4. For the pressure test of jacketed equipment, test the inner cylinder first and then the jacket ； 5. The requirements for the voltage withstand test will be clearly stated in the as-built drawings.
I didn’t understand your third point – isn’t -0.1 Mpa within the range specified in GB150?
Bro, it’s fine to perform cross-talk, but when you do it in such a serious manner, it can mislead people
Thank you for the answer! Do you mean that it is confirmed that if internal pressure of -0.1 and jacket pressure of 0.4 occur simultaneously, the actual hydraulic test pressure should be calculated as 1.25*0.5=0.6?
Thank you for such a detailed answer. But the second point is still a bit vague; do you mean that the hydrostatic test should be carried out using the most stringent negative pressure value, namely 0.5*1.25=0.6? Thirdly, according to GB150, a value of -0.1 MPa can be used together with the formulas provided there to determine the thickness and confirm the hydrostatic test pressure.
Yes, based on the information you provided, if the design pressure of the inner cylinder is -01 MPa and the design pressure of the jacket is 04 MPa, then the actual hydrostatic test pressure should be calculated as 125 times the internal pressure, that is, 125 * (-01) = -12.5 MPa. However, the hydrostatic test pressure cannot be negative, so it needs to be set to 0; therefore, the actual hydraulic test pressure should be 0 MPa. .