The International Building Code (IBC) did not require ultrasonic testing (UT) of complete joint penetration (CJP) welds at all from the IBC 2000 code through the IBC 2009 code. However, during that time, IBC required the special inspector to be on-site full-time to inspect the CJP welds during project construction. This requirement for full-time inspection of CJP welds in the field was deleted from the IBC code with the 2012 edition.
The 2012 IBC shifted the oversight of steel construction and steel special inspections to the AISC 360 model code (specifically AISC 360-10, Chapter N). This shift replaced the old IBC code terms “periodic” and “continuous” inspection with the new AISC 360 terminology, “observe” and “perform” tasks. While AISC 360, Chapter N, no longer requires full-time visual inspection, it still requires non-destructive testing (NDT), such as UT, on CJP welds in certain Risk Categories (II, III, and IV) and in seismic applications to ensure internal weld quality and integrity.
AISC 360, Chapter N, Section 5b, “Quality Control and Quality Assurance,” was first introduced in AISC-10. The 30 pages of Chapter N replaced the old AISC 360, Chapter M, which was a single page. Section 5b clearly requires UT of applicable CJP welds in material 5/16” thick or greater, including both field and fabrication shop welds. The project shop welds should be subjected to UT prior to shipping the steel elements to the project site for a host of reasons. When code-required UT is performed at the project site, the paint must be removed to reveal CJP welds before UT, which can be expensive. Performing UT in the fabrication shop results in significant cost savings for the project owner. The code allows the fab shop staff to conduct the UT inspection under the supervision of the QA special inspector, subject to the approval of the building official and the Engineer-of-Record.
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AISC 360, Chapter N, Section 5b
For structures in risk category III or IV, UT shall be performed by QA on all complete-joint-penetration (CJP) welds subject to transversely applied tension loading in butt, T-, and corner joints, in material 5/16 inches thick or greater. For structures in risk category II, UT shall be performed by QA on 10% of CJP groove welds in butt, T-, and corner joints subject to transversely applied tension loading in materials 5/16 inch thick or greater.
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For more information or further enthusiastic discourse on topics of CODE, please contact Alan Tuck at: [email protected] or 540.344.7939.
