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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