STRESS IN TANKERS' CAST IRON MANIFOLD FLANGES

In the past, when rubber dock hose was used for cargo transfer, tanker manifold piping and presentation flanges commonly were constructed of cast iron due to its relatively high corrosion resistance. With the advent of all-metal marine loading arms, the low strength cast iron manifolds occasionally failed from the higher loads imposed by the arm. The present trend is to supply new tankers with steel manifolds that have higher ultimate tensile strengths and are more ductile than cast iron. However, to insure safe operations at marine terminals, when a wide range of vessels is encountered, manifold stress analyses still must be executed based on the lower strength cast iron. To improve these analyses, Exxon Research and Engineering Company (ER&E) conducted laboratory studies of stresses in cast iron manifolds utilizing strain-gauged cast iron spools. Also the effect of different bolting procedures, gasket type, and gasket material on the critical stress were studied. The lab test bolting procedures examined in the tests were representative of actual field practices at marine terminals. The major study result is that stresses in cast iron manifolds may be much higher than previously believed. Measured stresses roughly ranged between 5000 to 15000 psi versus the allowable stress for cast iron of 3500 psi assumed (based on ASTMA126 gray pit cast iron with an ultimate strength of 21000 psi).

Media Info

  • Features: References;
  • Pagination: p. 525-532

Subject/Index Terms

Filing Info

  • Accession Number: 00138255
  • Record Type: Publication
  • Source Agency: Offshore Technology Conference
  • Report/Paper Numbers: V3, OTC 2664 Proceeding
  • Files: TRIS
  • Created Date: Sep 4 1976 12:00AM