| 摘要 |
Air is passed under pressure into a pipe under test and into a reference chamber connected to the pipe by a valve while recording at intervals of every few seconds the temperature in the reference chamber the temperature in the pipe and the absolute pressure in the reference chamber When the test pressure has been reached the valve is closed and the differential pressure between the pipe and the reference chamber is measured. The valve is opened to equalise the pressure and then closed again and the differential pressure drift rate is measured. This is repeated several times. A computer is used to calculate a creep prediction curve. A comparison is made to see whether the pressure drift rate due to creep and leak only in the pipe independent of any temperature change in the pipe is trending towards crossing the curve or not.
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