Villy Inspection Case Share(lesson for procurement):
A Costly Crack-Why Your PO Must Address ET Blind Zones

The Case: ExxonMobil Golden Pass LNG Project (GPX, 2020)
During a routine inspection of the tube-to-tubesheet assembly, our surveyor discovered a crack at the end of a tube.
Independent Lab Analysis (SGS) Conclusion for this crack:
- The tube's material properties (mechanical, hardness, chemistry) were fully compliant.
- The root cause was a defect in the original billet end. This defect, carried through manufacturing, resulted in a crack because the standard Eddy Current Testing (ET) blind zone at the tube end was not addressed.
The Corrective Action (NCR Closure):
The supplier had to implement extensive and costly measures:
1. Perform Liquid Penetrant Testing (PT) on both ends (200mm) of all finished tubes.
2. Perform PT on both ends of all tubes in warehouse stock.
3. For future production: Cut 200mm from both ends after ET to physically remove the blind zone material.
Note: Cutting this length was not originally planned, highlighting added cost and material planning challenges.
The Key Lesson for Procurement:
The ~200mm blind zone at tube ends is a well-known limitation of standard ET. However, common standards (like ASTM) do not mandate how to manage it.
If your Purchase Order (PO) or ITP is silent on this point, suppliers will typically only perform a basic visual check on the ends, leaving a critical quality risk uncovered.
Our Professional Advice:
True quality control means proactively managing known risks. On your next tubing RFQ/PO, explicitly specify one of these solutions:
"Supplemental 100% UT or PT inspection on both tube ends (min. 200mm)."
"A defined length (e.g., 200mm) shall be removed from both ends after ET."(Plan for longer billets).
Clear specifications prevent costly surprises, rework, and project delays.