This book presents guidelines on quantitative and qualitative measures of the geometric features and imperfections of welds to ensure that it meets the fatigue strength requirements laid out in the recommendations of the IIW (International Institute of Welding). Welds that satisfy these quality criteria can be assessed in accordance with existing IIW recommendations based on nominal stress, structural stress, notch stress or linear fracture mechanics. Further, the book defines more restrictive acceptance criteria based on weld geometry features and imperfections with increased fatigue strength. Fatigue strength for these welds is defined as S-N curves expressed in terms of nominal applied stress or hot spot stress. Where appropriate, reference is made to existing quality systems for welds.In addition to the acceptance criteria and fatigue assessment curves, the book also provides guidance on their inspection and quality control. The successful implementation of these methods depends on adequate training for operators and inspectors alike. As such, the publication of the present IIW Recommendations is intended to encourage the production of appropriate training aids and guidelines for educating, training and certifying operators and inspectors.

This book presents guidelines on quantitative and qualitative measures of the geometric features and imperfections of welds to ensure that it meets the fatigue strength requirements laid out in the recommendations of the IIW (International Institute of Welding). Welds that satisfy these quality criteria can be assessed in accordance with existing IIW recommendations based on nominal stress, structural stress, notch stress or linear fracture mechanics. Further, the book defines more restrictive acceptance criteria based on weld geometry features and imperfections with increased fatigue strength. Fatigue strength for these welds is defined as S-N curves expressed in terms of nominal applied stress or hot spot stress. Where appropriate, reference is made to existing quality systems for welds.In addition to the acceptance criteria and fatigue assessment curves, the book also provides guidance on their inspection and quality control. The successful implementation of these methods depends on adequate training for operators and inspectors alike. As such, the publication of the present IIW Recommendations is intended to encourage the production of appropriate training aids and guidelines for educating, training and certifying operators and inspectors.

Engineering structures for reliable function and safety have to be designed such that operational mechanical loads are compensated for by stresses in the components bearable by the materials used. Vhat is "bearable"? First of all it depends on the properties of the chosen materials as well as on several other parameters, e.g. temperature, corrosivity of the environment, elapsed or remaining serviceable life, unexpected deterioration of materials, whatever the source and nature of such deterioration may be: defects, loss of strength, embrittlement, wastage, etc. DEFECTS and PROPERTIES of materials currently determine loadability. Therefore in addition to nondestructive testing for defects there is also a need for nondestructive testing of properties. The third type of information to be supplied by nondestructive measurement pertains to STRESS STATES under OPERATIONAL LOADS, i.e. LOAD-INDUCED plus RESIDUAL STRESSES. Residual stresses normally cannot be calculated; they have to be measured nondestructively; well-approved elastomechanical finite element codes are available and used for calculating load-induced stresses; for redundancy and reliability, engineers, however, need procedures and instrumentation for experimental checks.