Radiographic testing, in which X-rays or a gamma source such as iridium-192 pass through the weld onto film or a digital detector, recording internal discontinuities as density differences. It shows volumetric flaws like porosity, slag and incomplete penetration well, and planar flaws like lack of fusion only when they line up with the beam. Image quality indicators verify sensitivity, and the area is cleared during exposures.
RT crew shoots tonight after nine, everybody's off the rack by then.
A clean film is not proof of a sound thick weld: lack of fusion lying at an angle to the beam can be invisible on RT.
Also heard as
- radiography
- X-ray
- film
- digital radiography
Do not mix it up with
- UT: RT records a picture of density differences and favors volumetric flaws, while UT reads sound reflections and is better at planar flaws like cracks and lack of fusion.
Related terms
Shot
Shop word for a radiograph of a weld, or the act of X-raying it, as in the weld got shot.
UT
Ultrasonic testing: finding internal flaws by sending high-frequency sound into a weld and reading echoes.
Porosity
Gas bubbles trapped in weld metal as it freezes, showing as round holes on the surface or on film.
Slag inclusion
Nonmetallic slag trapped inside a weld instead of floating out to the surface.
Wagon tracks
Radiographer slang for two parallel lines of slag trapped along the edges of a root pass.