What is the minimum hydrostatic test requirement for shutoff valves, in relation to the rated service pressure?

The minimum hydrostatic test requirement for shutoff valves in relation to the rated service pressure is indeed four times the rated service pressure. This requirement ensures that the valves can withstand pressures well above their normal operating conditions, thereby demonstrating their integrity and performance under potential stress scenarios.

During the hydrostatic testing process, valves are filled with water and subjected to pressure levels significantly higher than what they will experience in regular service. Testing valves at four times the rated service pressure provides a safety margin, allowing for any potential weaknesses in the material or construction to be identified before the valves are put into service.

This heightened testing requirement is crucial in maintaining safety standards and reliability in systems that utilize compressed natural gas, as it helps to prevent leaks and failures that could lead to dangerous situations. By ensuring that shutoff valves can handle such extreme pressures, operators can be more confident in the overall safety and integrity of the CNG distribution system.