The owner or operator of a VOC storage tank with an external floating roof shall perform the following actions:

1. (a) A visual inspection of the secondary seal gap during semi-annual inspections; and

2. (b) When the roof is equipped with a vapor-mounted primary seal, annual measurement of the secondary seal gap in accordance with the following procedure:

   1. (1) The length and width of all gaps around the entire circumference of the secondary seal shall be measured in each place where a 0.32 cm or 0.125 in. uniform diameter probe passes freely, without forcing or binding against the seal, between the seal and tank wall; and
   2. (2) The sum of the areas of the individual gaps shall be calculated.

Source. #7788, eff 10-31-02; ss by #9802, eff 10-31-10 (from Env-A 804.19); ss by #12762, eff 5-1-19