SELECTION OF SAMPLES FOR LABORATORY EVALUATION
If possible, remove the entire failure region with some adjacent sound
If failure sites are numerous, try to select samples of failure sites with
different appearances and/or from locations with potential differences in operating conditions.
In many cases, it is useful to remove mating components, as well as the
failed parts, e.g. collect the nuts from failed fasteners or gears and bearings with a failed
For large structures, obtain material sample(s) well away from the failure
to allow comparison of materials properties, e.g. sample a ruptured boiler tube at the failure
and in a colder region, such as near the tube sheet.