L. Vonbernus et al., CURRENT IN-SERVICE INSPECTIONS OF AUSTENITIC STAINLESS-STEEL AND DISSIMILAR METAL WELDS IN LIGHT-WATER NUCLEAR-POWER-PLANTS, Nuclear Engineering and Design, 151(2-3), 1994, pp. 539-550
A tendency towards growing requirements for the inspection of austenit
ic piping can be observed in several countries. In Germany the revised
KTA rule demands the UT inspection of austenitic and dissimilar metal
welds in piping with diameters of 200 mm or more. On the basis of exp
erience gained from austenitic piping with integranular stress corrosi
on cracking (IGSCC), longitudinal waves and mode conversion techniques
are used. Depending on the geometry, material and grain orientation,
spurious signals can be observed which require additional evaluation o
r analysis measurements. A promising new technique is based on horizon
tally polarized shear (SH) waves generated by electromagnetic acoustic
transducers (EMATs). Investigations in the laboratory and field inspe
ctions showed that SH waves are well suited for the detection of longi
tudinal flaws, especially where the weld can be examined from one side
only. For the complete solution of a given inspection problem SH wave
s can be combined with well-known standard techniques in order to prov
ide redundant information for the characterization and sizing of indic
ations. The investigation of possibilities of SH waves showed that the
problem of cast austenitic steel inspection might not be solved using
this technique. However, measurements using low frequency UT transduc
ers showed promising results.