CARGO TANK CLEANING AND VAPOR CONCENTRATION STUDIES, S.S. RALPH B. JOHNSON

The results of vapor concentration tests taken during a ballast voyage are presented. Sampling occurred before, during and after tank cleaning, done either by Butterworthing or the "Yo-Yo" procedure. The tank vapor concentrations were expressed in terms of flammability levels at 50, 30 and 10 foot levels. One hour after stripping, the atmosphere at the 50 and 30 foot level was within the flammable range. Forty hours after stripping all sampling levels tended toward homogeneity above the upper flammability limits. Ballasting left vapor concentrations in the flammable range at the 30 and 10 foot level while the vapor concentration at the 50 foot level remained above the upper flammability level. In time, the tank atmosphere became uniform throughout and concentrations remained around the middle of the flammable range. Butterworthing reduced the vapor concentrations slightly and tended to make the tanks homogeneous. The Yo-Yo procedures succeeded in cleaning the tank for clean ballast but did not gas-free the tank to a level considered safe for man to enter. Gas-free tanks were then accomplished by ventilation after ballasting.

• Corporate Authors:

  Chevron Research Company

  576 Standard Avenue, P.O. Box 1627
  Richmond, CA  United States  94802
• Authors:
  • Cates, M F
• Publication Date: 1970-7-27

Media Info

• Pagination: 28 p.

Subject/Index Terms

• TRT Terms: Cleaning; Flammability; Storage tanks; Vapors
• Old TRIS Terms: Gas freeing; Gas vapor concentration; Tank cleaning; Vapor flammability levels
• Subject Areas: Maintenance and Preservation; Marine Transportation; Safety and Human Factors;

Filing Info

• Accession Number: 00043953
• Record Type: Publication
• Source Agency: Mine Safety Appliances Research Corporation
• Files: TRIS
• Created Date: May 4 1973 12:00AM