LONG TERM MOORING AND ANCHORING OF LARGE STRUCTURE AND DRILLING UNITS. (RELIABILITY AND SAFETY OF ANCHOR CHAIN SYSTEMS)

The experience from the rough and stormy North Sea has given new and valuable information on anchor chain and anchoring systems. A series of failures which have occurred during the last four years, did initiate an extended investigation to find the reason of these failures. These investigations consisted of, in chronological order: 1) Metallurgical Lab. Failure Investigations. 2) Study of Bending Strength and Strain. 3) Full Scale Bending Tests with Natural Flaws. 4) Dynamic Field Stress Measurements. 5) Ultrasonic Investigations of Sub-stud Cracks. 6) Basic Anchor Chain Testing; -- Full scale study of the importance of flaws, -- Development of full scale toughness test method, weld region. 7) Strain Gauge Measurement during Anchor Chain Proof Tests. To complete the picture, the following items were studied: 8) Chain Link Stresses in fairleads. 9) The Possibility of Stating a Real Fracture Load. 10). Anchor Chain Quality. -- Base material and anchor chain specifications. 11) Anchor Chain Production, Quality Assurance. 12) Anchor Chain System. -- Fairlead design. Service conditions. -- Maintenance. -- Chain accessories. Some of the anchor chain manufacturers have already today achieved a high level of consistant quality through a good workmanship or reliable automatization of vital production steps. By taking into consideration the proposed modifications and precautions, it is believed that anchor chain systems shall give a reliable and safe operation performance.

  • Supplemental Notes:
    • This paper was presented at the 12th Annual OTC in Houston, Texas, May 5-8, 1980.
  • Corporate Authors:

    Offshore Technology Conference

    6200 North Central Expressway
    Dallas, TX  United States  45206
  • Authors:
    • Berg, A
    • Taraldsen, A
  • Publication Date: 1980

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Filing Info

  • Accession Number: 00325766
  • Record Type: Publication
  • Source Agency: Offshore Technology Conference
  • Report/Paper Numbers: Volume 3 Proceeding
  • Files: TRIS
  • Created Date: Mar 12 1981 12:00AM