What is a standard method to verify brazed joint integrity for fluid systems?

• A. Radiographic inspection only.
• B. Visual inspection alone.
• C. Dye penetrant testing.
• D. Pressure testing (or leak testing) with inert gas or water; optionally helium leak testing for high sensitivity.

Answer: (D)

Testing for leaks by pressurizing the brazed joint is the standard way to verify fluid-system integrity. By applying pressure with an inert gas or water and then watching for pressure loss or visible leaks, you directly assess whether the joint can seal under service-like conditions. Using an inert gas keeps the test safe and avoids chemical reactions, while water allows easy visual indication of leaks as bubbles. If you need the highest sensitivity, helium leak testing can be added because helium difuses through very small leaks and can be detected with specialized equipment.

This approach is preferred because it confirms the primary function of the joint—to prevent fluid escape—under actual or representative operating pressures. Other methods look at surface condition or internal features but don’t guarantee sealed performance. Radiographic inspection shows internal structure but not whether a leak exists under pressure; visual inspection and dye penetrant testing can identify surface flaws but cannot reliably reveal hidden leaks or overall joint sealing.