Section 157.600 - Purpose and applicability(a) The purpose of this subpart is to establish mandatory safety and operational requirements to reduce environmental damage resulting from the discharge of other non-petroleum oil.(b) This subpart applies to each tank vessel specified in § 157.01 of this part that- (1) Is 5,000 gross tons or more;(2) Carries other non-petroleum oil in bulk as cargo or cargo residue; and(3) Is not equipped with a double hull meeting § 157.10d of this part, or an equivalent to the requirements of § 157.10d , but required to be equipped with a double hull at a date set forth in 46 U.S.C. 3703a (b)(3) and (c)(3) .