How to check for airtightness after the pre-operational purging of the production unit is completed
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After the pre-operational purging of the production unit is completed, how can it be made airtight? The system’s design pressure ranges from -0.01 MPa to 3.0 MPa – how should airtightness be ensured in such cases, and what precautions should be taken? I have encountered situations where airtightness testing was carried out at low pressures during startup, only to experience leaks at high pressures; this is extremely dangerous! ! ! ! !
In November, we completed the airtightness testing of a set of equipment with pressure levels similar to those of yours; the two distillation towers were connected together, and the designed maximum pressure was 0.35 MPa. We filled it with compressed air at 0.25 MPa and maintained that pressure for 24 hours. No overpressure was detected, so further airtightness testing was not necessary, as the distillation towers are equipped with burst discs for protection
But you need to know that the operating pressure of our reactor is 2.6 MPa; airtightness at 0.2 MPa is simply not reliable. Moreover, it is a hydrogen-handling facility, and any leakage would be extremely dangerous
Does this question seem a bit too broad? We usually use soapy water to check for leaks; if a leak is found, it’s sufficient for the delivery staff to tighten it up, while in some cases the gasket needs to be replaced. If there is anything wrong, please feel free to point it out
A simple home method for airtightness, using bubbles. In some situations, bubbles cannot be used; instead, testing instruments are required, which increases the number of maintenance points and failure points. Some also rely on human judgment. High-pressure airtightness still needs to be ensured at the manufacturing plant. If there is any damage at the site, the manufacturer must conduct another inspection. After all, safety first.
Especially in areas with high pressure, it is essential to ensure a tight seal; otherwise, if a leak is detected after material is introduced, the consequences can be very serious. The air compressor can be used to increase the pressure to the normal design value; during this process, the airtightness is checked in three steps, namely by raising the pressure to 1.0 Mpa, 2.0 Mpa, and 3.0 Mpa.
The pressure testing range should cover the normal operating pressure! Both high pressure and low pressure need to be tested
In our company, the airtightness is required to be at least 1.2 times the designed pressure, and leak checks are carried out using soapy water; any leaks are not allowed.
Seal the sections one by one; at the connections between high pressure and low pressure, start with the high-pressure side first. However, install a bleed valve at the low-pressure side and keep it slightly open to prevent high pressure from leaking into the low-pressure area
Don’t you do pressure tests? Using water pressure is better than air pressure for detecting leaks. Our unit is small; prior to operation, it undergoes purging, a hydrostatic test is carried out, and any leaks are repaired after the pressure test, with the airtightness pressure remaining between 0.8 and 1.0. The maximum pressure of the device is 2.5; it is considered qualified if the pressure remains stable for a certain period of time. Our system contains hydrogen and NH3. But I’m not sure if what we’re doing is proper; this is the way we have handled the airtightness check after parking and before driving over the years.
To distinguish between hydrostatic testing and airtightness testing, hydrostatic testing generally requires a certain pressure level, which is 1.2 times the design pressure. Airtightness testing, also known as tightness testing, does not require such high pressures; moreover, airtightness testing is generally not permitted for pressure vessels/pipelines, as it can be extremely dangerous if the vessel/pipeline fails under these conditions. The design specifications for the airtightness test pressure will specify requirements