Page 45 - Handbook of Structural Steel Connection Design and Details

Fasteners and Welds for Structural Connections

30 Chapter One

been completed, inspected, and accepted. Before paint is applied, spat-
ter, rust, loose scale, oil, and dirt should be removed.
AWS D1.1 presents details of techniques acceptable for welding build-
ings. These techniques include handling of electrodes and fluxes.

1.3.6 Weld quality
A basic requirement of all welds is thorough fusion of weld and base
metal and of successive layers of weld metal. In addition, welds should
not be handicapped by craters, undercutting, overlap, porosity, or
cracks. (AWS D1.1 gives acceptable tolerances for these defects.) If
craters, excessive concavity, or undersized welds occur in the effective
length of a weld, they should be cleaned and filled to the full cross sec-
tion of the weld. Generally, all undercutting (removal of base metal at
the toe of a weld) should be repaired by depositing weld metal to
restore the original surface. Overlap (a rolling over of the weld surface
with lack of fusion at an edge), which may cause stress concentra-
tions, and excessive convexity should be reduced by grinding away of
excess material (see Figs. 1.13 and 1.14). If excessive porosity, exces-
sive slag inclusions, or incomplete fusion occur, the defective portions
should be removed and rewelded. If cracks are present, their extent
should be determined by acid etching, magnetic-particle inspection, or
other equally positive means. Not only the cracks but also sound metal
2 in beyond their ends should be removed and replaced with the weld
metal. Use of a small electrode for this purpose reduces the chances
5
of further defects due to shrinkage. An electrode not more than ⁄32 in in

Figure 1.13 Profiles of fillet welds.

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