Leak detection forms an important part of quality control step in welded components and assemblies. In recent past, designers have been specifying leak tightness as per different codes like ASME, ASTM,BIS etc. to different degrees of leak tightness as demanded by their intended use. In nuclear technology, because of radioactive hazard considerations, leak tightness of high degree (Around 1x10~(-8) std.cc/sec.) is generally specified on many components and assemblies. To detect leaks of this order mass spectrometer type helium leak detectors are extensively used. Normally helium leak detection is being carried out at room temperature, However in many applications the components I assemblies operate at higher temperature. for increased performance reliability of these components / assemblies at higher temperature, it is desirable to do helium leak testing at higher temperature simulating the operating conditions. Hence since past few years designer's have been specifying helium leak testing at higher temperature. One such facility has been designed, developed and fabricated at author's plant to carry out helium leak testing at 350°/550°C on special nuclear components by bombing technique. This is being done for the first time in the country. This paper describes the techniques of high temperature helium leak testing and gives details of test set-up, test method, calibration procedure and test results etc.
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