Section 157.146 - Similar tank design: Inspections on U.S. tank vessels(a) If a U.S. tank vessel has tanks similar in dimensions and internal structure, the owner or operator may submit a written request to the Officer in Charge, Marine Inspection, of the zone in which the COW system is inspected, for only one of those tanks to be inspected under § 157.140(a)(1) .(b) Only one tank of a group of tanks similar in dimensions and internal structure is inspected under § 157.140(a)(1) , if the Officer in Charge, Marine Inspection, accepts the request submitted under paragraph (a) of this section.