Abstract

For many decades it has been known that one can accurately define the fault size in weld joint by the use of non destructive examination (NDE). Because of different materials, loaded in an extended level of varieties which additionally suffer under different corrosion attack condition, the dilemma is arising how to assess reliably the allowable fault size in different weld joint parts. The presence of faults is obvious but the possibilities to reveal them are limited and not always possible. For the structure capacity of bearing under high loading the weld joint faults size and their distribution are the essential parameters. The larger the allowable fault size anticipated, the safer the welded structure, the easiest the detection of the fault size by NDE methods can be. Thus, for assessing the safety of complex loaded welded structure, machine parts or equipment life time, it is obligatory to consider the requirements of different "Fitness for Purpose" systems. The article presents the possibility of assessing the detected fault by means of NDE if the material fracture toughness of the area where the fatigue crack tip located is known. The fatigue crack represents the severest possible discontinuity that can occur in a welded joint. The principles of HW Guidance on Assessment of The Fitness for Purpose of Welded Structures - IIW/IIS-SST-1 157-90 and BS PD 6493 and separately ET model that treats mis-matched weld joints are shown and used.

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Source: Conference Proceedings of the 4th International Conference of the Slovenian Society for Nondestructive Testing, 24 - 25 April 1997, Ljubljana, Slovenia.
Pages:257 - 270

Publisher:
Slovenian Society for Nondestructive Testing, Faculty of Mechanical Engineering, Askerceva 6, SLO 1000 Ljubljana, Slovenia. Tel +386 61 177 12 03, Fax +386 61 218 567, Email: janez.grum@fs.uni-lj.si.