10.017  UT Acceptance Criteria - FEMA-353 vs. AWS D1.1

I need some advice on the UT acceptance criteria for CJP welds. The welding inspector for the project that I'm working on claims that the acceptance criteria specified in AWS D1.1 differs from that specified in FEMA-353, and he is asking us to specify which criteria they should use. Our project uses special moment resisting frames, so the welds at the connections and the column splices are critical elements. The project specifications state the following:   "Ultrasonic testing (UT) shall be conducted by the Owner's Testing Agency for the percentage of joints designated in Table 2-1. UT shall be performed in accordance with AWS D1.1." FEMA-353 is cited elsewhere in the specifications but not in regards to UT. I looked at AWS D1.1 and cannot determine if or how it differs from FEMA-353. I also reviewed AWS D1.8 and it appears to match FEMA-353 and thus adds to my confusion.

What concerns me about the specification is that I'm sure that the differences between AWS D1.1 and FEMA-353/D1.8 were not taken into account when the provision was written. That's why I need the clarification. Should we be using D1.8 or D1.1 or both?

-- Structural Engineer from Oakland, CA.

7/23/06 - Response prepared by Dave Palfini, Principal, ASNT Level III, and AWS SCWI, Testing Engineers, Inc., San Leandro

AWS D1.1 has two ultrasonic testing procedures and acceptance criteria. The primary one, used for decades and most commonly accepted, is contained in Section 6, Part F.

Annex K, referenced in FEMA-353, UT Examination of Welds by Alternate Techniques, is relatively new. Since FEMA-353 was not specified for ultrasonic testing in the project documents, AWS D1.1, Section 6, Part F would be the procedure to be used. Some reasons for this are as follows:

FEMA-353, Section 5.8.3 allows the engineer the option of either AWS D1.1 Annex K or Table 6.2 (Section 6, Part F).

Annex K (moved to Annex S in 2006), states, "This annex is non-mandatory unless specified in the contract documents."

AISC 341s1-05 and AWS D1.8-06 specify AWS D1.1, Section 6, Part F unless alternative procedures are approved by the engineer.

7/23/06 - Response prepared by Doug Williams, Consulting Metallurgical and Welding Engineer

If given the choice, I prefer the D1.1 criteria, primarily because there are precious few UT technicians that can accurately and reliably size flaws in 3 dimensions. As the welding inspector suggests in his original request, the FEMA-353 criteria may not be as conservative as D1.1, particularly considering the lower probability of detection and accuracy of sizing for technicians whose experience is predominantly with the D1.1, Sec. 6, Parts C & F criteria and methods.