A 4" natural gas pipe must be purged with inert gas before servicing. What is the maximum length of pipe before purging is required?

In the context of natural gas systems, purging is a critical safety procedure that is required to remove any combustible gas from a pipeline before servicing. This is particularly important because even a small amount of natural gas can pose a significant risk of explosion or fire when maintenance is being performed.

The requirement to purge a section of pipe depends on its length and configuration. For a 4" natural gas pipe, purging is mandated when the length exceeds 15 feet. This standard is in place to ensure that the risk of having combustible gases present is minimized, especially in longer segments where gas may accumulate or persist.

Therefore, the maximum length of pipe before purging is necessary is established at 15 feet, indicating that any section that exceeds this length must undergo purging with inert gas to ensure the safety of the technicians and the integrity of the system while being serviced.