PRESSURE AND VACUUM RELIEF SYSTEMS FOR TANKERS

The authors question the requirement of many authorities for a flame screen below any pressure vent. The velocity of released gases will always exceed the speed of flame propagation. This is perhaps one of the rules which tends to obscure the major problem because any loss of inlet pressure can have a very detrimental effect upon the operation and efficiency of a high velocity jet stream valve. A flame screen mounted below the valve only serves to impair the performance of the valve and does nothing to increase safety. Gas inerting will remove one hazard i.e. that of fire of an explosion in a tank but it only reduces the hazard caused by the release of hydrocarbon gases into the atmosphere. One must also have some regard for the toxic effects of hydrocarbon vapors: this is in a sense a secondary hazard because the consequences are neither so sudden or so devastating but nevertheless concentrations at deck level of only 4 per cent of Lower Explosion Limit can have a toxic effect upon the crew. This toxic effect is even more serious when hydrogen sulphide, aromatics or organic lead compounds are present in the cargo.

  • Corporate Authors:

    North East Coast Inst of Engineers & Shipbuilders

    Bolbec Hall, Westgate Road
    Newcastle upon Tyne,   England 
  • Authors:
    • Paterson, IWF
    • Watson, P B
  • Publication Date: 1974-7

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00080014
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: May 1 1975 12:00AM