An Eddy Current scanner has been developed that rapidly inspects composite overwrapped metallic pressure vessels liners and thin wall metallic pressure vessels for small external and internal surface cracks. Flaws detection sensitivity is greater than any other inspection method currently available.

1. Eddy Current Testing of COPVs
Project Overview
An Eddy Current scanner has been developed that rapidly inspects composite
overwrapped metallic pressure vessels liners and thin wall metallic pressure
vessels for small external and internal surface cracks. Flaws detection sensitivity
is greater than any other inspection method currently available.
Relevance
Flaw detection in metallic liners used in Composite Overwrapped Pressure
Vessels (COPVs) has been a major problem, especially considering the trend
toward thinner liners. Flaws can grow with vessel pressure cycling causing
leakage or possible vessel rupture. To preclude this, the liner must be inspected
prior to wrapping. The industry has used florescent dye penetrants to inspect for
flaws, however this is time consuming, subject to human error, and lacks the
necessary sensitivity and consistency for critical flaws in thin vessels.
Furthermore, dye penetrant cannot be used to inspect the liner after wrapping
when autofrettage can grow flaws.
Outcome
Following fabrication of an internal eddy current probe, numerous scans were
recorded to determine the sensitivity of the system. The system was able to
detect flaws as shallow as 0.006” with widths as narrow as 0.003”. The team is
currently working to acquire test articles containing even narrower flaws in order
to push the limits of the system. Key members of the test team include NASA
Project Manager Regor Saulsberry, operators and experimenters Ralph
Lucero, Kyle Carver, Charles Nichols, Paul Spencer, and NASA graduate student
Dan Wentzel who is the internal probe designer.
External and Internal Eddy Current System Internal Eddy Current Attachment Low Resolution Internal Survey Scan
Zoom View of Indications from the Survey
Scan Shown Above
Internal Attachment Scanning a Specialized
Flanged Test Article
External Application of an Eddy Current Probe