This amendment clarifies a pipeline safety regulation regarding the period for comfirmation or revision of a pipeline's maximum allowable operating pressure (MAOP). Under the present regulation, the MAOP of a pipeline must be confirmed or reduced within 18 months after a population increase near the pipeline results in a more restrictive class location. Some operators have misinterpreted this rule to preclude confirmation of the pre-existing MAOP at a date beyond the 18-month period if the initial action taken is to reduce the MAOP. The amendment makes it clear that confirmation by pressure testing may occur at any time after the 18- month period, if the initial compliance action was to reduce the MAOP under § 192.611(b).