Texas Compressed Natural Gas (CNG) Delivery Truck Driver Practice Exam

A shutoff valve must be capable of withstanding four times the rated service pressure during a hydrostatic test. This requirement ensures that the valve can handle extreme pressures that may occur during operation without failing. The hydrostatic test is a critical assessment for pressure-containing components in a gas system, as it verifies the integrity and reliability of the valve under conditions that exceed normal operating pressures. This fourfold safety factor is crucial for maintaining system safety, allowing for the possibility of pressure surges, temperature variations, and material fatigue over time. Therefore, design standards for shutoff valves stipulate that they must meet this stringent testing criterion to ensure that they can safely function and prevent leaks or catastrophic failures in the event of pressure anomalies.