How Many Kinds of Pressure Tests Are There?

The pressure test of heat exchanger includes hydraulic test and pneumatic test.
 
In principle, the pressure test should be mainly hydraulic test. It is often called hydro-static test when clean water is used for the test. If other liquids are used as the test medium, the medium should be non-hazardous and its temperature should be lower than the boiling point. When a flammable liquid is used for a hydraulic test, the test temperature must be lower than the flash point of the flammable liquid. At the same time, there should be no fire source near the test site, and it should be equipped with appropriate fire fighting devices.
 
The air pressure test can be carried out according to the design drawings when the pressure vessel cannot be completely filled with liquid due to structural or supporting reasons, and the pressure vessel whose operating conditions do not allow residual test liquid. For example, the volume of the container is too large to bear the weight of water, such as large spherical tanks, cement foundations, pillars and other occasions with such difficulties; the structure is complex, and the hydraulic test is not enough to fully test the pressure of each part. Because only gas phase load is considered in the structure design, the load produced during the hydro-static test will bring damage to the structure, or the medium of hydro-static test will cause corrosion damage to the shell wall and inner lining of the container.