Radiography - Coggle Diagram
transmission of ionising radiation through a material
film or fluorescent screens
to detect changes in density and thickness
internal and surface breaking defects.
types of radiation
absorbs less radiation than the parent material
image appears black
Pipeline weld inspections - internal - using X or gamma-ray crawlers.
Pipe weld inspections - external - using X and gamma-ray.
Welders' test pieces - permanent record.
Last castings - for void and segregation content.
Pipework corrosion surveys - using double-wall double-image shots with gamma radiation.
Submarine or surface ship insert welds.
decay of unstable radioactive isotopes
Half life -5-26 years
Energy level - 1,170-1,330keV
Half life - 32 days
Energy level - 50-300keV
Half life - 74 days
Energy level - 300-600keV
lead lined container
milliamperage controls the quantity of radiation
Benson Line focus
controls the energy level / penetrating power
Image quality indicators (IQIs)
assess the contrast and definition of the radiographic image
placed on shims
across the object
Radiograph sensitivity = Diameter of smallest visible wire / Thickness of test object x 100%
In weld radiography a sensitivity of 2% or better is aimed for.
Step-hole type = Diameter of smallest visible hole / Thickness of test object x 100%
Ionising radiation is a serious health hazard.
A time consuming process when film development is taken into account.
Expensive both in capital costs and in providing radiographic film.
Two sides of test piece have to be accessible.
Interpretation of radiographs requires skill.
Can be sensitive to defect orientation and so can miss planar flaws.
A permanent record is produced.
Good for measuring volumetric defects (porosity, inclusions).
Can be used on a wide variety of materials.
The method makes it possible to inspect in accessible structures and assemblies.