VENT SYSTEM AND LOADING CRITERIA FOR AVOIDING TANK OVERPRESSURIZATION

The extent of cargo tank overpressure during transfer operations was analyzed, taking into account cargo properties, tank characteristics, loading rate, and vent system design. It was found that typical venting systems in use today have more than adequate capacity for gas venting, but inadequate capacity for liquid overfill. The margins of safety for gas venting appear to be about a factor of three in loading rate and a factor of ten in the effective length to diameter ratio of the vent system. Cargo volatility has a relatively small effect on the potential overpressure hazard. For the case of liquid overfill, the maximum permissible ratio of loading rate (cu-ft per sec) to vent cross sectional area (sq-ft) is 9 ft/sec. Many cargo transfer operations currently equal or exceed this value. Furthermore, tank failure would be expected less than one minute after the tank becomes liquid full. (Author)

• Corporate Authors:

  Little (Arthur D), Incorporated

  Acorn Park
  Cambridge, MA  United States  02140
• Authors:
  • Wilson, RPJ
  • Raj, PKP
• Publication Date: 1977-9

Media Info

• Pagination: 87 p.

Subject/Index Terms

• TRT Terms: Container tanks; Loading and unloading; Marine safety; Pressure relief valves; Safety equipment; Safety valves; Tankers; Ventilation systems; Vents
• Old TRIS Terms: Cargo tanks; Loading handling; Overpressure; Tank venting; Tanker loading; Tanker safety; Venting
• Subject Areas: Marine Transportation; Safety and Human Factors;

Filing Info

• Accession Number: 00167368
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: ADL-77396-3 Final Rpt., USCG-D-59-77
• Contract Numbers: DOT-CG-42357-A
• Files: NTIS, TRIS
• Created Date: Dec 27 1978 12:00AM