Welding Defects and Conditions.
The face of the weld is a comparatively wide band, which is the actual width of the bead covering the entire area to be
examined. The cover bead area should have enough density to distinctly show surface ripples. But it should not be so
dark as to obscure subsurface regions.
This appears on the radiograph as a dark line of some width at the junction of the weld and the plate. A fine line in
this darker area may indicate a crack at the fusion line and should be further investigated.
Excessively High Cover.
Where radiation exposure is satisfactory, a cover bead of this kind will appear as a very transparent area, obscuring all
but major subsurface defects. When such an excessively high cover bead extends for a considerable distance, the bead
should be ground and re-examined so that cracks or other hard-to-find defects may not be overlooked.
Either on the bead or plate next to the weld, this will appear on the radiograph as a light spot. Although not a defect in
itself, splatter may cover some more serious defects.
Arc Tracks and Burns.
These result from carelessness on the part of a welder in striking an arc at the side of the welding groove. Such tracks
are readily recognized on the radiograph. A burned spot may show a small "star" or lines radiating from the center
which are actually cracks in the plate. In the cover bead these are frequently heavy, leaving an almost blank area on
the film and obscuring subsurface defects. These are points that frequently harbor inclusions and cracks.
These will appear in the weld as rather fine lines, either parallel to or transverse to the weld. Such surface cracks are
frequently found near or at the edge of the weld, or follow a ripple across the weld.
Narrow Cover Bead.
This may indicate either of two conditions. The bead may actually be of less width than the subsurface weld, in which
case a differential in density will be noted between the edge of the weld, or the plate material may be mismatched.
Offset Cover Bead.
Where the cover bead is not placed directly over the remainder of the weld, the radiograph will show the relative
positions of the cover and root beads. In severe cases these two beads may be side by side instead of superimposed;
such a condition may definitely weaken the weld structure.
Gas pockets are usually spherical and are readily recognizable as dark spots the intensity of which varies directly with
their diameter. Gas pockets are not peculiar to any one spot in the weld and may be fairly well scattered.
Slag and Wagon Tracks.
Isolated slag deposits usually form an irregular body and are most frequently found at the edge or fusion line of the
particular bead. The most frequent type of slag deposits are found between the first or root pass and the second pass.
Such slag deposits may be quite long and appear as lines of some width. Where such lines are found on both sides of
the root bead they are commonly referred to as "wagontracks." These frequently have considerable length but seldom
are of excessive width. Isolated slag pockets on the other hand frequently have decided width as well as length.
Generally, the density of a slag inclusion is rather uniform throughout.
In the path of radiation these are readily distinguished as fine lines of considerable length but without great width.
Generally, they do not follow a straight course. At an angle to the source of radiation, cracks are difficult to recognize