What is the most significant defect to be checked while performing the visual inspection of welds?

After welding, visual inspection can detect a variety of surface flaws, including cracks, porosity and unfilled craters, regardless of subsequent inspection procedures. Dimensional variances, warpage and appearance flaws, as well as weld size characteristics, can be evaluated.

Before checking for surface flaws, welds must be cleaned of slag. Shotblasting should not be done before examination, because the peening action may seal fine cracks and make them invisible. The AWS D1.1 Structural Welding Code, for example, does not allow peening "on the root or surface layer of the weld or the base metal at the edges of the weld."

Visual inspection can only locate defects in the weld surface. Specifications or applicable codes may require that the internal portion of the weld and adjoining metal zones also be examined. Nondestructive examinations may be used to determine the presence of a flaw, but they cannot measure its influence on the serviceability of the product unless they are based on a correlation between the flaw and some characteristic that affects service. Otherwise, destructive tests are the only sure way to determine weld serviceability.

Undercut, surface crack, Lack of fusion.burn through.

Cracks and Discoloration Solid inclution, Rootpass,   

cracks -cavities-incomplet fustion-miscelinous -solid inclusion-imperfect shap

lack of fusion

incomplete pentration

porosity 

undercut

lack of fusion 

incomplete pentration

Welders’ certificates, Slag cleaning, Incomplete welds

Under cut,Capping defects,Slag,Creater crack,Ark stricks,under fills,porosity

Weld bead profile inlcuding undercuts/underfills if any, all of which could act as stress raisers, need to be primarily checked. Toes need to be smoothly blended to ensure no sudden change is there in the weld contour. These are the most basic and the most missed out aspects while performing visual inspection.

Befor welding starat compleet chek out the External Tump And weld Metal and filer Metal