What is the most likely cause if all of the flange bolts in an insulated flange show high resistance?

When all of the flange bolts in an insulated flange show high resistance, this can indicate an issue related to the insulation properties of the flange assembly. In particular, the presence of high resistance typically suggests that there is an insulating gasket that is functioning as intended, creating a separation in electrical conductivity between the flanges.

If there were a short across the insulating flange gasket, the expectation would be for low resistance measurements, indicating that electrical paths are being formed incorrectly across what should be an electrically insulating barrier. However, the observation of high resistance implies that the insulation is intact and performing properly, preventing current from passing through.

In contrast, issues like a defective bolt or stud would more likely lead to instability or failure of the bolted joint rather than solely high resistance readings. A voltage surge could also cause erratic behavior but is less likely to consistently show high resistance across all bolts unless extensively affecting the entire assembly. Similarly, while a failed grounding cell or decoupler could introduce issues with grounding and electrical isolation, it would not specifically result in uniformly high resistance readings across all bolts, but rather an inconsistency in measurements depending on the area affected.

Therefore, the indication of high resistance in all bolts points specifically to the insulating gasket functioning correctly, confirming that choice