NDT Level III Personnel Qualification Certification for UT - Leak Testing Outline
About Leak Testing (LT)Leak Testing is used to detect through leaks using one of the four major LT techniques: Bubble, Pressure Change, Halogen Diode and Mass Spectrometer Testing.
- Bubble Leak Testing relies on the visual detection of a gas (usually air) leaking from a pressurized system; Pressure Change Leak Testing can be performed on closed systems only-- detection of a leak is done by either pressurizing the system or pulling a vacuum then monitoring the pressure.
- Halogen Diode Leak Testing is done by pressurizing a system with a mixture of air and a halogen-based tracer gas-- after a set period of time, a halogen diode detection unit, or "sniffer", is used to locate leaks.
- Mass Spectrometer Leak Testing can be done by pressurizing the test part with helium or a helium/air mixture within a test chamber then surveying the surfaces using a sniffer, which sends an air sample back to the spectrometer.
This examination is 4 hours in length, having 135 questions of equal value.
- Principles theory
- Physical principles in leak testing
- Principles of gas flow
- Proper selection of LT as method of choice
- Leak testing standards
- Detector/instrument performance factors
- Vacuum pumps
- Bubble testing practices and techniques
- Absolute pressure testing equipment
- Absolute pressure hold testing of containers
- Absolute pressure leakage rate testing of containers
- Analysis of data for determination of accurate results
- Halogen testing equipment
- Helium mass spectrometer testing equipment
- Bubble test
- Pressure change/measurement test
- Halogen diode detector leak test
- Mass spectrometer leak testing
- Helium mass spectrometer vacuum testing by dynamic method
- Helium mass spectrometer vacuum testing by static method
- Basic techniques and/or units
- Test materials and equipment effects
- Effects of temperature and other atmospheric conditions
- Calibration for testing
- Probing/scanning or measurement/monitoring
- Leak interpretation evaluation
- Acceptance and rejection criteria
- Leak testing procedures
- Leak testing specifications
- Safety and Health
- Safety considerations
- Safety precautions
- Pressure precautions
- Safety devices
- Hazardous and tracer gas safety
- Types of monitoring equipment
The number in parentheses following each reference is the ASNT catalog number.