Final answer:
A high pressure leak test is essential when adding more than 20 feet to an existing gas piping system to ensure safety and efficiency, as gas moves from areas of high to low pressure and leaks can result in hazardous conditions.
Step-by-step explanation:
When adding a section of more than 20 feet to an existing gas piping system, it is indeed crucial to perform a high pressure leak test. Gas systems operate based on the fundamental principle that gas moves from an area of high pressure to an area of low pressure. This characteristic implies that any leaks present would allow gas to escape, potentially creating safety hazards or affecting the efficiency of the system. Performing a high-pressure leak test ensures that the new and existing sections are properly sealed and can maintain the required pressure without leaks.
Moreover, considering example B.4.2, gas stored at high pressures requires containers that can withstand significant pressure and safety factors to account for unexpected conditions, such as fires. These stringent requirements highlight the importance of ensuring the integrity of gas systems. Regular testing, especially when modifications like adding significant lengths to piping are made, is imperative for safety and functionality.