How to test the airtight of heat exchanger?

In the "Pressure Vessel Periodic Inspection Rules", the following requirements for airtight test operation of heat exchanger are specified:

1. When the pressure vessel is tested for air tightness, the safety accessories shall be fully assembled;

2. the pressure rises slowly, when the test pressure reaches 10% should be suspended when the pressure, the sealing parts and welds to check, if no leakage or abnormal phenomenon can continue to boost;

3. step-up should be increased step by step, each level can be 10% to 20% of the test pressure, between each level should be appropriate to maintain pressure to observe whether the abnormal phenomenon;

4. to reach the test pressure, the inspection without leakage and abnormal phenomena, holding pressure of not less than 30min pressure is not reduced is qualified. It is forbidden to use continuous pressurization to maintain the same test pressure;

5. When there is pressure, do not fasten the bolt or repair work.

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