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Leakage Testing (LT)

Leakage testing is focused on the detection of the imperfections in the solid boundary-line, which allow escaping of liquids (in presence of the pressure gradient). This method is able to detect imperfections of the material failure of metallurgical or technological process or in-service induced imperfections, mechanical joints (welds, solved, cemented and soldered joints).

The dimension of the leak is represented by the volume of the substances passing through the leakage per unit of time. Basically two general types of exams are recognized - integral test (for determination of the total value of the leakage) and localization test (focused on the determination of the leakage position).

Testing methods / techniques

• method of measurement of micro-flow (overpressure/vacuum)
• pressure change method (increase / decrease of the pressure, overpressure of the liquid, gas, ...)
• bubble method (overpressure, vacuum with vacuum box)
• penetration method (Liquid penetrant passes through the examined object)
• helium method - tracer gas method (test medium is He, overpressure, vacuum, ...)
• other (ultrasound scanning, ...)

The suitable method and technique is determined in accordance with required test sensitivity, tested part character (shape, construction, dimensions (volume), ...), legal requirements, and customer's requirements.

Methodic requirements for LT testing are established by standards, codes specifications and customers' requirements.


LT testing in accordance with EN is based on the following standards
Basic EN standards with relationship to LT are

• EN 1518 - Characterization of mass spectrometer leak detectors
• EN 1593 - Bubble emission techniques
• EN 1779 - Criteria for method and technique selection
• EN 13184 - Pressure change method
• EN 13185 - Tracer gas method
• EN 13192 - Calibration of reference leaks for gases
• EN 13625 - Guide to the selection of instrumentation for the measurement of gas leakage

The most important and the most often required standards and specifications for LT are ASTM E 1003 (Hydrostatic testing) ASTM E 515 (bubble method), ASTM E 493, 498, 499, 1066 (mass spectrometer), than ASME Code and other.

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