X = 0.55 * Y (Eq. 1)
Where:
X = Number of calendar days allowed to complete corrective action or increase coking time; and
Y = Current coking time for the oven, hours.
For the purpose of determining the number of calendar days allowed under Equation 1 of this section, day one is the first day following the day you observed an opacity in excess of 30 percent for any short battery or 35 percent for any tall battery. Any fraction produced by Equation 1 of this section must be counted as a whole day. Days during which the oven is removed from service are not included in the number of days allowed to complete corrective action.
40 C.F.R. §63.7291