How are petrochemical plants subjected to strength testing or airtightness testing?
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I recently encountered a troublesome issue and would like to seek advice from the experts here. The fertilizer plant was shut down for 5 months; before it can be restarted, a gas-tightness test is required. The normal operating pressure range of the device is quite wide, from negative pressure to 16.0 MPa. There are currently the following issues that require expertise to resolve: 1. The entire device has multiple pressure levels, and according to the requirements for airtightness testing, it is necessary to isolate the sections with different pressure levels and conduct tests on each section separately. However, since the design originally aimed to prevent leaks at the flanges by using direct welding connections, it is not possible to isolate them with blind plates. 2. The pressure of nitrogen or air is relatively low, and it cannot reach above 1.0 MPa. After major overhauls in the past, we would fill it with nitrogen to a pressure of 0.7–0.8 MPa and maintain that pressure to detect leaks. But it has been shut down for 5 months now, so I don’t dare to do that. Faced with such a problem, I would like to ask experts how to solve it? 3. Do other refineries have compressors designed specifically for airtightness testing?
1. For airtightness testing, systems at different pressure levels don’t require blind flanges; valves can be used for isolation instead. 2. After a long period of downtime, it is recommended not to raise the pressure too much at first – check for leaks first, and only then increase the pressure gradually. 3. There are specialized air compressors that can generate very high pressures