46 C.F.R. § 153.434 Heat transfer coils within a tank.
Title 46 - Shipping
When a cargo tank contains any quantity of cargo, a cargo cooling or heating system having coils within the tank must keep the heat transfer fluid at a pressure greater than the pressure exerted on the heating or cooling system by the cargo. [CGD 78–128, 47 FR 21209, May 17, 1982]
Title 46: Shipping
PART 153—SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS
Subpart B—Design and Equipment
Cargo Temperature Control Systems
§ 153.434 Heat transfer coils within a tank.

