Page 280 - Handbook of Structural Steel Connection Design and Details
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Welded Joint Design and Production
Welded Joint Design and Production 265
and moisture. However, those issues seem to pose less of a problem
than do the management-oriented issues.
Generally, gasless welding processes, such as self-shielded flux
cored welding, and shielded metal arc welding are preferred for field
welding. Gas metal arc, gas tungsten arc, and gas-shielded flux cored
arc welding are all limited due to their sensitivity to wind-related gas
disturbances. Regarding managerial issues, it is imperative that field
welding conditions receive an appropriate increase in the monitoring
and control area to ensure consistent quality. The AWS D1.1 code
imposes the same requirements on field welding as on shop welding.
This includes qualification of welders, the use of welding procedures,
and the resultant quality requirements.
3.9.7 Inspection
To ensure weld quality, a variety of inspection activities is employed. The
AWS D1.1 code requires that all welds be inspected, specifically by
means of visual inspection. In addition, at the engineer’s discretion and
as identified in contract documents, nondestructive testing may be
required far finished weldments. This enables the engineer with a
knowledge of the complexity of the project to specify additional inspec-
tion methodologies commensurate with the degree of confidence required
for a particular project. For seismically loaded structures, and connec-
tions subject to high stress levels, the need for inspection increases.
In-process visual inspection. The D1.1 code mandates the use of in-
process visual inspection. This activity encompasses those operations
performed before, during, and after welding that are used to ensure
weld quality. Before start-up, the inspector reviews welder qualification
records, welding procedure specifications, and the contract documents
to confirm that applicable requirements are met. Before welding is
performed, the inspector verifies fit-up and joint cleanliness, examines
the welding equipment to ensure it is in proper working order, verifies
that the materials involved meet the various requirements, and con-
firms that the required levels of preheat have been properly applied.
During welding, the inspector confirms that appropriate WPS para-
meters are being achieved and that the intermediate weld passes
meet the various requirements. After welding is completed, final bead
shapes and welding integrity can be visually confirmed. In spite of its
apparent simplicity, effective visual inspection is a critical component
for ensuring consistent weld quality.
Nondestructive testing. There are four major nondestructive testing
methods that may be employed to verify weld integrity after the weld-
ing operations are completed. None is a substitute for effective visual
inspection as outlined previously. No process is completely capable of
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