46 C.F.R. § 154.528 Piping joints: Flange type.
Title 46 - Shipping
(a) A flange must be one of the following types: (1) Welding neck. (2) Slip-on. (3) Socket weld. (b) If the piping is designed for a temperature between −10 °C (14 °F) and −55 °C (−67 °F), the pipe flange may be a: (1) Slip-on type, if the nominal pipe size is 100 mm (4 in.) or less; (2) Socket weld, if the nominal pipe size is 50 mm (2 in.) or less; or (3) Welding neck. (c) If the piping is designed for a temperature lower than −55 °C (−67 °F), the pipe flange must be a welding neck type.
Title 46: Shipping
PART 154—SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES
Subpart C—Design, Construction and Equipment
Cargo and Process Piping Systems
§ 154.528 Piping joints: Flange type.
