Hydrostatic testing for portable propane cylinders is typically required every how many years?

• A. Every 2 years
• B. Every 3 years
• C. Every 4 years
• D. Every 5 years

Answer: (D)

Hydrostatic testing checks that a cylinder can safely hold its pressure over time without leaking, distorting, or failing. For portable propane cylinders, the standard interval is every five years. During the test, the cylinder is filled with water and pressurized to a level higher than its normal service pressure; this reveals any weaknesses in the wall or fittings by showing leaks, bulges, or distortion. If the cylinder passes, it’s stamped with a new test date indicating it’s good for another five years.

Why five years? Corrosion and metal fatigue develop gradually, so a five-year interval catches significant deterioration before it becomes dangerous, while keeping downtime reasonable. Shorter intervals would impose unnecessary testing without a proportional safety gain, and longer intervals could miss emerging flaws.