I am ultrasonically testing a PQR plate prior to mechanical testing and I came across a situation. I just bought a DSC block so that I can have a more portable option for calibration. I used it for the first time on this plate and I was finding a -0.5 Db indication about 1" long. I decided to break out my IIW type 2 to compare and make sure I was getting consistent results. With my IIW calibration the indication was exactly the same location (depth and length) except the indication is now 5Db.

I did some google fu and found some previous posts in this forum that talked about having to use the IIW block and the DSC block in conjunction with each other and finding the difference in reference level and adjusting to match. From what people were saying, AWS D1.1-06  6.23.1 said to do this.

I do not see any such reference in AWS D1.1-20, did something change or am I just missing it? 8.27.2.4 and G2.4.1 have the same verbiage for "attaining a horizontal reference line height indication". I am also going to ask my level III for some direction but his specialty is not in AWS so I figured I would ask you guys as well.