I do not have the code to hand, however from memory your option 2 is the correct one.

I would not bet any money on it though before I read the code again.

To calculate sensitivity for a DWDI (Double Wall Double Image) technique, the job thickness you should consider is option 3:(5.54+1.5)X2

This is because in DWDI, the X-ray beam passes through two walls (each with its own thickness, including weld reinforcement), so the effective thickness for sensitivity calculation is the sum of both walls.

Refer to Section V of ASME BPVC (Article 2, Mandatory Appendix I), where guidelines for determining sensitivity and thickness for DWDI are typically discussed. Ensure to verify your calculation with the specifics of the code edition you're using.

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option 3