Which test checks the joint tightness under pressure?

• A. Joint Tightness Test
• B. Valve Seat Tightness Test
• C. Hydrostatic/Pneumatic Test
• D. System Drop Test

Answer: (C)

Testing joint tightness under pressure is achieved with a hydrostatic/pneumatic test. This approach seals the system and then applies pressure using liquid or gas, watching for any pressure drop or visible leaks. If joints or connections aren’t sealing properly, the pressure will decrease or leaks will appear, confirming which joints need attention and ensuring the entire system can hold pressure as intended.

The other options don’t fit as well because they describe more specific or different checks: a Joint Tightness Test typically targets a particular joint rather than the whole system; a Valve Seat Tightness Test checks the sealing of a valve’s seating surfaces when the valve is closed, not the system’s overall joints under pressure; a System Drop Test focuses on the system’s response to a deliberate pressure drop rather than verifying tightness of joints under operational pressure.