ASME BPVC Section V: NDT Method Discipline

What the standard covers

The section covers NDT methods, their qualification and the discipline around documentation. A composites programme reads it for the method practice rather than for acceptance criteria, because the acceptance limits for a blade come from IEC 61400-5 Table G.1 while the method discipline comes from a code like this one.

What it demands

• A defined method with documented technique and qualification
• Calibration records that tie the run to a reference
• A recording threshold and a disposition for every indication above it
• Documentation a qualified reviewer can follow without the operator present

How it lands on a blade scan

The section matters on a composites programme as a pattern rather than a clause. The documentation chain it implies, coverage maps, daily calibration on reference blocks and an indication log above a recording threshold, is the same chain IEC 61400-5 expects at a certification audit. When a system generates that chain automatically per blade serial, a 3-day audit becomes a 3-hour document review. That is the practical value of borrowing method discipline from a code written for another industry, the discipline transfers even when the code does not.

How to apply it to a blade

Run these checks in order. By Step 5 the scan plan has the threshold, the geometry and the record it needs.

1. Fix the acceptance threshold. Start from the threshold the zone carries, not from the method you happen to own. IEC 61400-5 Section 11 asks for volumetric detection of indications 6 mm and larger in the laminate plane, and DNV-ST-0126 tightens the leading edge to 3 mm, so the threshold is set before the probe is chosen.
2. Read the geometry off the drawing. Measure the thickness and the curvature the probe has to travel. A spar cap up to 80 mm of unidirectional laminate and a root transition of changing radius are two different scan problems, and the radius decides how the array is coupled.
3. Choose the modality pair. Pick modules by defect geometry, not by habit. PAUT images planar separations that lie parallel to the plies, TOFD catches volumetric clusters whatever their orientation, and running both on a 256-channel system puts the two mechanisms in one pass.
4. Automate the scan path. Put the probe on an encoder-driven carriage and let the path, not the technician, set coverage. A 600 mm spar cap falls to one longitudinal pass at 500 mm/s on a linear array, where a single-element probe needs 20 parallel passes and runs about five times longer.
5. Lock the evidence chain. Write the coverage map, the daily calibration and the indication log to the blade serial while the scan is running. It is the difference between a 3-day type-certification audit and a 3-hour document review, and it is what ISO 9712 qualification is there to sign.

The numbers below are drawn from the equipment records and field campaigns this site already publishes, not from a generic catalogue.