A boiler can be hydrostatically tested using water at what temperature?

• A. 100° F
• B. 50° F
• C. 212° F
• D. 32° F

Answer: (A)

During hydrostatic testing, water is used to pressurize the boiler to check for leaks and strength. The temperature of that test water matters because heating the water causes thermal expansion, which adds extra pressure independent of the boiler’s actual strength. Keeping the test water near room temperature and not exceeding about 100°F minimizes this unwanted pressure, giving a more accurate assessment of the vessel’s integrity without risking thermal stress. Water hotter than that, like boiling at 212°F, would artificially raise pressure and could damage components or mask leaks; very cold water could introduce other issues. So using water at about 100°F is the standard practice, making that temperature the correct choice.