During a pressure test, the test object is connected to a test machine with a closed test room. Most tests are carried out with a liquid as test medium. The pressure is increased by adding medium. Energy is loaded into the test object. The moment the test object proves not to be strong enough during pressurization, a rupture can occur and the stored energy is released. Test medium will be released with great force and depending on the setup, the test object or parts of it may shoot away. This can damage the test room, As a result the test room needs to be repaired to withstand the impact of a subsequent test.
Factors affecting safety
There are several factors that influence safety in pressure testing. An important factor is the maximum pressure. The more pressure, the more the test medium is compressed and the more it expands. The volume also has an influence. Is a small quantity tested or a tank of 4000 liters. With a larger volume, more medium and therefore more energy is added. In the event of a rupture, more energy is released. The same is true for test objects that have a certain degree of elasticity. When a hose has an expansion of 10%, it also requires 10% more medium. There will be more energy storage.
The most dangerous and underestimated factor affecting safety is air inclusion. When air inclusion occurs in a test object, a dangerous situation arises. The danger is in the compressibility of air. Air stores a great deal of energy under pressure. Air inclusion occurs if, for example, a thick hose lies flat on the floor or on the bottom of the test room. There is a high risk of air inclusion in this setting. In the event of a fracture, the stored energy is released and the object can move in all directions. The stored energy is more than 1000 times higher with gas compared to liquid at a test pressure of, for example, 1000 bar. In the event of a rupture, we therefore do not speak of a leakage, but of an explosion.
How is safety guaranteed?
Carrying out a pressure test safely is a priority. There are several aspects to consider to ensure the pressure test is safe. For example, an emergency stop is safety aspect number one. It may sound logical, but it does not always appear to be present on the test machine. The test process can be stopped immediately with an emergency stop. A second aspect is a double-walled test room, so that the housing of the test machine is not damaged in the event of a loose test object. A double lock ensures that no pressure can be built up as long as the lid or door is still open. A human error is immediately prevented.
Heavy locks and sufficient hinges ensure that the test room door remains in place and does not get knocked out. Vent valves allow escaping air to be released more quickly. In addition, stainless steel panels ensure that there is no weakening due to corrosion. All these aspects together ensure that the objects are tested in a safe test room. For the protection of personnel and to prevent damage to the testing machine.
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