33 C.F.R. § 401.73 Cleaning tanks—hazardous cargo vessels.
Title 33 - Navigation and Navigable Waters
Cleaning and gas freeing of tanks shall not take place: (a) In a canal or a lock; (b) In an area that is not clear of other vessels or structures; and (c) Before gas freeing and tank cleaning has been reported to the nearest Seaway station. [55 FR 48599, Nov. 21, 1990]
Title 33: Navigation and Navigable Waters
PART 401—SEAWAY REGULATIONS AND RULES
Subpart A—Regulations
Dangerous Cargo
§ 401.73 Cleaning tanks—hazardous cargo vessels.

