Why are many gas lines found to be undersized?

Many gas lines are found to be undersized primarily because of the addition of equipment not originally planned for. When a system is first installed, calculations are made to determine the appropriate size of the gas lines based on the expected load. However, over time, as businesses expand or change their operations, new appliances and equipment that require gas may be added. If the original line was sized only for the initial load without accounting for future growth or equipment additions, it can result in a situation where the existing gas line cannot handle the increased demand. This can lead to insufficient gas supply for the new appliances, which can affect performance, safety, and efficiency.

The other factors listed can contribute to problems in a gas system, but they do not specifically address the sizing issue as directly as the addition of unplanned equipment. Using low-quality materials can affect durability and safety, incorrect installation can lead to leaks or operational issues, and using industrial pipes in domestic applications introduces compatibility issues rather than directly affecting the sizing of the existing gas lines. Thus, the most significant reason for undersized gas lines is often the incremental demands placed on a system through the addition of equipment that wasn't included in the original design.