The underwater wet welding method for repairing of submerged structural members has been intensively developed during the last years. It is an economical and especially more time-independent procedure. The shortened repair duration is a major advantage in regions with rough sea climate as the North Sea area. During research projects the weldability and fatigue performance of pipe-patch connections have been tested. These joints are in use for repairing of collision indents. The shape of the actual used repair patch was optimized to the requirements of underwater wet welding at high tensile strength steels as BS4360 Gr 50D. Steel materials in this grade show problems in regard to high hydrogen susceptibility, and therefore cold cracking. The fatigue behavior of the patch-welded pipe structural member has been investigated. First test series were carried out using as-welded joints. In a second part of the project, post-weld-treated connections were tested. The weld seams on these joints were partially ground or hammer peened. The test results have been evaluated by means of the hot-spot concept and then faced with actual code requirements. Extensive strain gage measurements and finite-element calculations have been carried out to provide the stress state in the structural details.

Issue Section:
Research Papers
Topics:
Maintenance, Pipes, Testing, Welding, Fatigue, Steel, Climate, Collisions (Physics), Cracking (Materials), Finite element analysis, Fracture (Process), Hammers, Hydrogen, North Sea, Seas, Shapes, Strain gages, Stress, Structural elements (Construction), Surface roughness, Tensile strength
1.
H.-G., Schaffstall, and R., Schaefer, “Naßschweißen unter Wasser-Entwicklungsaktivita¨ten fu¨r die Meerestechnik” (Underwater Wet-Welding—Activities in Development for Marine Technologie), DVS-Band 31, Deutscher Verlag fu¨r Schweißtechnik, Du¨sseldorf, 1979.
2.
C. E. Grubbs, “Underwater Wet Welding—A State of the Art Report,” Proceedings of the 12th International Conference on Offshore Mechanics and Arctic Engineering, ASME OMAE, Vol. III-A, pp. 111–118, 1993.
3.
C. L. Tsai, “Underwater Wet Welding Cuting and Inspection,” Welding Journal, Feb. 1995.
4.
P. Szelagowski, H. Stu¨hff, H.-G. Schafstall, I. Pachniuk, and J. Blight, “Wet Welding—An Available Alternative for Platfrom Repair,” GKSS-Forschungszentrum Geesthacht GmbH/Comex Services, Marseille, 1994.
5.
R. Pohl, H. Petershagen, and A. Krohn, “Gestaltung und Betriebsfestigkeit von Unterwasser-Reparaturschweißungen an Offshore-Konstruktionen” (Design and Fatigue Strength of Underwater Repair-Welding on Offshore Constructions), Institut fu¨r Schiffbau der Universita¨t Hamburg, Bericht Nr. 568, 1996.
6.
DIN 17100: “Allgemeine Bausta¨hle-Gu¨tevorschriften” (Steels for General Structural Purposes—Quality Standard), Beuth Verlag, 1973.
7.
S. J. Maddox: Fatigue Strength of Welded Structures, Abington Publishing, Cambridge 1991.
8.
Almar-Naess A., Fatigue Handbook-Offshore Steel Structures, Tapir, 1985.
9.
A. Hobbacher: “Fatigue Design of Welded Joints and Components,” Recommendations of IIW Joint Working Group XIII-XV, XIII-1539-96/XV-845-96, Abington Publishing Cambridge, 1996.
10.
“Rules and Regulations. I—Ship Technology, Part 1: Seagoing Ships, Chapter 1 Hull Structures (1-1-1),” Germanischer Lloyd, 1997.
11.
W. Fricke, H. Petershagen: “Anwendung o¨rtlicher Konzepte auf die Betriebsfestigkeit schiffbaulicher Konstruktionen” (Application of the Local Concept for Fatigue Strength of Ship Structures), Berechnung, Gestaltung und Fertigung von Schweißkonstruktionen im Zeitalter der Expertensysteme, EXPERT’91, DVS-Band 133, Deutscher Verlag fu¨r Schweißtechnik, 1991.
12.
H. Petershagen, W. Fricke, and H. Paetzold, Fatigue Strength of Ship Structures, Germanischer Lloyd, 1997.
13.
E. Haibach: “Betriebsfestigkeit—Verfahren und Daten zur Bauteilberechnung” (Fatigue Strength), VDI-Verlag, 1989.
14.
Department of Energy: “Rules for the Design, Construction and Maintenance of Offshore Structures,” HMSO, London 1990.
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