There are a number of defect types that occur in welds in rail.
These can all be detected in principle but there are practical difficulties
with all the methods in use brought about by the railway
environment. Consequently, the most common, and mandatory,
inspection method is visual inspection with various other
inspection methods required if visual inspection reveals any
problems.
None of the methods in routine use produces automatic,
auditable records of inspection integrity.
Techniques are in development for examinations that would
reduce the requirement for skilled operators and produce complete
records of the test.
Once a weld is in service it is inspected as equivalent to plain
rail by all the methods in routine use. ❖