NDT - Non-Destructive Testing Leak Testing Techniques Questions and Answers

Question 1

A technician must verify the integrity of a hermetically sealed electronic component for a deep-space satellite, where even a minuscule leak is unacceptable.
Which of the following leak testing methods offers the highest sensitivity for this application?

Accepted Answer

Helium mass spectrometer testing

Answer

Bubble emission testing

Answer

Halogen diode detector testing

Answer

Absolute pressure leak testing

Question 2

When selecting a tracer gas for leak testing, which of the following is a critical property for ensuring high sensitivity and minimizing false readings?

Accepted Answer

Low background concentration in the atmosphere

Answer

High molecular weight to prevent rapid dispersion

Answer

Chemical reactivity with the test object's surface

Answer

High visibility under ultraviolet light

Question 3

An inspector is performing a leak test on a large vessel that has been pressurized with a helium-air mixture. The inspector moves a probe connected to a mass spectrometer over the exterior surface of the vessel to pinpoint the location of any leaks. What is this specific technique called?

Accepted Answer

Detector probe technique

Answer

Tracer probe technique

Answer

Pressure decay method

Answer

Bubble immersion technique

Question 4

During a bubble leak test using a soap solution on a pressurized gas line, the technician observes a single, large bubble that forms immediately upon application and then remains without growing or bursting. What is the most likely interpretation of this observation?

Accepted Answer

Entrapped air from the initial application of the solution

Answer

A very large, high-pressure leak is present

Answer

The test solution has too high a viscosity

Answer

A very small leak or "weep" is present

Question 5

Which of the following is a standard unit used to express a leak rate, representing a throughput of gas?

Accepted Answer

Atmosphere cubic centimeters per second (atm·cm³/s)

Answer

Pascals per second (Pa/s)

Answer

Liters per minute (L/min)

Answer

Pounds per square inch per hour (psi/hr)

Question 6

Which of the following leak testing methods relies on monitoring the change in pressure inside a sealed component over a specified period to determine if a leak is present?

Accepted Answer

Absolute pressure testing

Answer

Halogen diode testing

Answer

Mass spectrometer testing

Answer

Bubble emission testing