I assume your question comes up by QW-193.1.3 (a) and (e) (Acceptance Criteria — Macro‐Examination, Tube‐to‐tubesheet tests) – unfortunately you do not mention the paragraph.
Please remember QW-193 is very similar to Article F-3 of the old ASME VIII/2 and was removed from ASME VIII/2 and added in ASME IX with the Edition 2004, Addenda 2006.
Have a look at this old Article F-3 for a better clarification:
“ARTICLE F-3 SPECIAL REQUIREMENTS FOR TUBE-TO-TUBESHEET WELDS
....
AF-334 Examination
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The weld throats of all sections (minimum leakage path) shall be not less than two-thirds of the specified tube wall thickness and shall be free from cracks on visual examination with 10 magnification.”
That means minimum leakage path is the shortest route for a leak (for a fillet weld = throat thickness).
