What is the minimum length of a nipple that can be used for a sediment trap on a gas line?

The minimum length of a nipple used for a sediment trap on a gas line is indeed 3 inches. A sediment trap is a design feature intended to collect any condensate or sediment that may accumulate in the gas line, preventing it from entering the appliance. The 3-inch length is specified because it provides adequate volume to capture these materials while also ensuring that the gas flow is not significantly restricted. This standard helps to maintain the overall efficiency and safety of the gas system.

Using a nipple shorter than this could compromise the effectiveness of the sediment trap and allow sediments or moisture to reach the appliance, potentially leading to operational issues or safety hazards. Therefore, the requirement for a minimum length of 3 inches balances functionality and safety in gas line installations.