19 CFR 158.13 - Allowance for moisture and impurities.
(a) Application by importer -
(1) Petroleum and petroleum products. An application for an allowance in duties under section 507, Tariff Act of 1930, as amended (19 U.S.C. 1507), for all detectable moisture and impurities present in or upon imported petroleum or petroleum products shall be made by the importer on Customs Form 4315. The application shall be filed with the port director within 10 days of the port director's receipt of the gauging report or within 10 days of Customs acceptance of the entry's invoice gauge.
(2) Other products. An application for an allowance in duties under 19 U.S.C. 1507 for products other than petroleum or petroleum products for excessive moisture or other impurities not usually found in or upon such or similar merchandise shall be made by the importer on Customs Form 4315. The application shall be filed with the port director within 10 days after the report of weight or gauge has been received by the port director or within 10 days after the date upon which the entry or a related document was endorsed to show that invoice weight or gauge has been accepted by the Customs inspector or other Customs officer.
(b) Allowance by port director. If the port director is satisfied after any necessary investigation that the merchandise contains moisture or impurities as described in paragraph (a) of this section, he shall make allowance for the amount thereof in the liquidation of the entry.