1. Before the overall large air separation unit cold test. Fractionation should be fully heated and blown out. Air turbine compressor, turbine expander, air pre-cooling system, molecular sieve purification system and electrical, instrumentation and control system must be ready for operation.
2、The operation of the cold test is carried out in accordance with the operating instructions of the large air separation unit, in order to cool the distillation tower, the main condenser and other major large air separation unit to as low a temperature as possible, fighting all the containers in the cold box, the outer surface of the pipeline frost, and should be maintained for at least 2 hours.
3. In the cold test process, personnel should be organized to enter the cold box must wear cold hats, gloves, cotton clothing, etc. Strictly check the leakage parts and make marks. For cold valve, low temperature film adjustment valve can be used to tighten the nut with special tools. And should pay attention to the valve is not stuck phenomenon, cold test is over, but also natural reheat, as long as the cold box manhole cover can be opened, should be airtight test, but also dynamic test, so all the bolts, flange connections, valves and other parts shall be tightened once. To pay special attention to the tightening of the valve can not be completely closed state.
4. The overall cold test of large air separation unitshould generally be carried out twice， according to the test leakage and treatment.
