The test pressure for gas pipes should be no less than how many times the proposed maximum working pressure?

The correct answer is that the test pressure for gas pipes should be no less than 1 1/2 times the proposed maximum working pressure. This requirement is set to ensure the integrity and safety of the gas piping system.

By specifying that the test pressure must be 1 1/2 times the maximum working pressure, the code accounts for potential variations and unforeseen stresses that may occur in real-world usage. This ratio provides a sufficient safety margin to identify any leaks or weaknesses in the system before it is put into operation.

Testing at this increased pressure helps ensure that the materials and joints can withstand operating conditions, thereby enhancing overall safety and reliability. If the pressure was set at 1 time the maximum working pressure, it would not provide an adequate safety buffer, potentially allowing hazardous conditions to develop unnoticed. A ratio of 2 or 3 times, while it might sound safer, could be impractical in terms of the stresses imposed on the piping materials and joints, as well as the operational challenges it introduces during testing.

Thus, testing at 1 1/2 times the maximum working pressure strikes an effective balance between safety and practicality in maintaining the gas piping systems according to the standard practices outlined in the National Fuel Gas Code.