Corrosion Authority
Diagnostic

DC Interference Troubleshooting

Use evidence before diagnosis

This diagnostic uses observation → controlled checks → possible interpretation → next action. A potential shift or bond-current magnitude alone is not an automatic diagnosis.

Structure responds when a suspected rectifier is interrupted

Supported interpretation: the controlled source influences the measured electrical condition.

Still required: current/path/gradient and spatial evidence before concluding damaging discharge or its location.

More-negative shift with source ON

Possible interpretation: pickup/cathodic influence is plausible.

Check next: current/path/gradient evidence, IR drop, mixed potentials, and geometry. Do not treat the shift as proof of harmlessness or current direction.

Less-negative or more-positive shift with source ON

Possible interpretation: discharge/anodic influence is plausible.

Check next: confirm mechanism and location with current/path evidence. Potential alone is not proof of damaging discharge.

Bond current changes or reverses

Possible interpretation: source state is changing current transfer or relative driving conditions.

Check next: declared sign convention, synchronized source states, affected/interfering potentials, and current-path evidence. Reversal does not locate every pickup/discharge area.

Longitudinal current changes along the structure

Possible interpretation: net pickup/discharge within a segment is plausible.

Check next: interpret section balance using the declared current-direction convention and correlate with source and spatial evidence.

One area becomes more positive while another becomes more negative

Possible interpretation: a spatial discharge/pickup pair is plausible.

Check next: confirm with source, current, gradient, and geometry evidence.

Mitigation improves one location but worsens another

Supported interpretation: current distribution has been redistributed.

Next action: reassess the network and verify affected, interfering, and other relevant systems rather than accepting one improved reading as system-wide success.

Could this be normal CP attenuation?

If the pattern can be explained by normal CP distribution/attenuation and there is no external-source correlation, use Current Distribution & Attenuation. Unexpected attenuation is not automatically interference.

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