[Code of Federal Regulations] [Title 33, Volume 2] [Revised as of July 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 33CFR157.45] [Page 472] TITLE 33--NAVIGATION AND NAVIGABLE WATERS CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PART 157--RULES FOR THE PROTECTION OF THE MARINE ENVIRONMENT RELATING TO TANK VESSELS CARRYING OIL IN BULK--Table of Contents Subpart C--Vessel Operation Sec. 157.45 Valves in cargo or ballast piping system. When a tank vessel is at sea and the tanks contain oil, valves and closing devices in the cargo or ballast piping system or in the transfer system must be kept closed except they may be opened for cargo or ballast transfer to trim the vessel.