Hydraulic test issues
Thread Content
Article 3.8.2 of JB/T4735-97: When a container needs to undergo a hydraulic test, but the liquid filling height required for the hydraulic test is higher than the specified liquid storage height, and the design does not allow it, a combined hydraulic and pneumatic test can be used. ． ． ． ． ． Then inject compressed air into the upper part of the container until the gas phase space pressure reaches the test pressure value required by the drawing. ask: Will the gas phase space be dangerous during experiments? Is it safe?
No matter what pressure test the gas phase space is, it is dangerous and unsafe.
This is a tough question! In the petrochemical industry, generally speaking, the pressure for hydraulic tests is higher, set at 1.5 times the working pressure of the equipment, and the pressure for pneumatic tests is set at 1.1 times. Special equipment is made according to the design instructions. If you use a pneumatic test to replace a hydraulic test, if you use hydraulic parameters, you should carefully consider the safety.
For filters in the petrochemical industry, the hydraulic test is 1.25 times the design pressure when the temperature is not high.； When the design temperature is too high, the hydraulic test is 1.5 times the design pressure. For the air pressure test, it is the same as the design pressure. When designing the equipment, special attention must be paid to the selection and calculation of key components in the equipment. If there is a problem with one of them, no matter what the test is, it will be more dangerous. Among them, the air pressure test is generally not done because it is more dangerous.
Actually this is like this. The design pressure is greater than 0 and less than 0.1mpa. If only the air pressure test of the design pressure does not play a verification role, there is a 99% chance that the water pressure test will increase the basic investment. Therefore, the water is filled to the height of the liquid level and then inflated in the upper space to achieve the function of checking the bottom plate and the lower cylinder. It would be a lie to say that there is no danger at all because the pressure is so small. The water pressure test is also a little dangerous. To put it bluntly, there is a danger of having a ball when the air pressure is less than 0.1 MPa.
I have a question that I don’t understand. What is the danger in the air pressure test?
It is generally rare for you to ask you questions. It is very dangerous when doing hydraulic and pneumatic tests. When you are doing experiments on ordinary equipment. It is 0 where the test pressure is greater than the working pressure. 5 times must not be higher than the design pressure. Otherwise, the equipment will be damaged. And the preparation work when doing the test must be in place (for example. Set up a cordon). Also, is your equipment vertical or horizontal? If it is horizontal, have you done a drop-bearing test? If so, the liquid level of your equipment is at the required position for your test. Also consider whether the filter liquid will create pressure at a certain temperature. It is different from pipelines. The air tightness test of pipelines is 0. 4Mpa(G). Large pipelines also need to be blasted, which is very dangerous``
Air pressure tests generally involve certain risks, so regulations require on-site supervision by the safety department for air pressure tests.
Theoretically speaking, any pressure test is dangerous! But for normal pressure vessels, such a small pressure is actually not very dangerous, even if it explodes, it will be fine. .
It is obvious that the shock wave generated during the explosion is more harmful to gas than liquid. This is what we don't want to see.
The pressure is not high and there should be no major dangers.
This problem is really rare. The pressure is relatively small. The problem should not be too big or it must be careless.
The hydraulic test for high towers may have requirements for the foundation and load of the tower. In some cases, the water filling is too slow to meet the construction requirements. In other cases, the hydraulic test cannot be carried out during winter construction. Therefore, air pressure testing is used instead. The danger of air pressure testing is far greater than that of water pressure testing. Therefore, safety protection and isolation must be carried out when using air pressure testing to ensure safety during the pressure testing process.
However, generally speaking, those who can do hydrostatic testing generally do not agree that it is too dangerous to use air pressure testing instead of air pressure testing. However, in terms of cost, hydrostatic testing is more expensive than air pressure testing.
I have a question that I don’t understand. What is the danger in the air pressure test? The danger lies in the compressibility of gases! Liquids can be considered incompressible.