Abstract
On many occasions repairs are undertaken to ferritic steel weldments on plant either during construction or to remove service induced
defects. These repaired weldments are subsequently put into service with or without a post-weld heat treatment. In either case, but
particularly for the latter, there is a need to accommodate the associated residual stresses in structural integrity assessments such as those
based upon the R6 failure avoidance procedure. Although in some circumstances the residual macro-stresses developed within weldments of
components and structures can be calculated this is not so readily achieved in the case of residual stresses introduced by repair welds.
There is a range of physical and mechanical techniques available to undertake the measurement of macro-residual stresses. Of these X-ray
diffraction has the advantage that it is essentially non-destructive and offers the potential for evaluating stresses, which exist in the near
surface layer. Although for many structural integrity assessments both the magnitude and distribution of residual stresses have to be
accommodated it is not practical to make destructive measurements on weld repaired components and structures to establish the through
section distribution of stresses. An approach is to derive a description of the appropriate macro-stresses by a combination of measurement and
calculation on trial ferritic steel repair weldments. Surface measurements on the plant can then be made to establish the relationship between
the repaired component or structure and the trial weld and thereby improve confidence in predicted stresses and their distribution from the
near-surface measured values. Hence X-ray diffraction measurements at the near-surface of the plant weldment can be used to underwrite the
quality of the repair by confirming the magnitude and distribution of residual stresses used for the integrity assessment to demonstrate
continued safe operation.
q 2004 Elsevier Ltd. All rights reserved.
Translated title of the contribution | A strategy for accommodating residual stresses in the assessment of repair weldments based upon measurement of near surface stresses |
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Original language | English |
Pages (from-to) | 339 - 346 |
Number of pages | 8 |
Journal | International Journal of Pressure Vessels and Piping |
Volume | 82 |
Publication status | Published - 2005 |