Welding Imperfections according to BS EN ISO 6520-1

Definitions:
Imperfection Any deviation from the ideal weld.
Defect          An unacceptable imperfection.

BS EN ISO 6520-1 standard classifies the geometric imperfections in fusion welding dividing them into six groups:

1. Cracks. 

Imperfection produced by a local rupture in the solid state, which may arise from the effect of cooling or stresses. Cracks are more significant than other types of imperfection as their geometry produces a very large stress concentration at the crack tip making them more likely to cause fracture.

also read: Definition and Types of Cracks according to BS EN ISO 6520-1
2. Cavities. 

Cavity may be either gas cavity due to entrapment of gas or due to shrinkage caused by shrinkage during solidification.


3. Solid inclusions. 

Solid foreign substances trapped in the weld metal


4. Lack of fusion and penetration.

Lack of union between the weld metal and the parent metal or between the successive layers of weld metal.


5. Imperfect shape and dimensions. 

An irregular groove at the toe of a run in the parent metal or previously deposited weld metal due to welding. Characterised by its depth, length and sharpness.


6. Miscellaneous imperfections.

Local damage to the surface of the parent metal adjacent to the weld.