The only inspection techniques that have shown potential to determine, in a non-intrusive fashion, the mechanical stress on armour wires of flexible risers are the electromagnetic-based ones. Because the flexible pipeline is a complex multilayered structure of steel and thermoplastics, traditional inspection techniques cannot be used. Some electromagnetic methods are known to be able to run through the outer polymeric layer to sense the wires but the obtained data are very difficult to interpret. To date there is still no reliable and definitive solution to this problem, neither in the market nor in research groups. This present work analyses how the different electromagnetic techniques can be employed on inspection or monitoring of riser integrity. Experiments and simulations are used to discuss the advantages and limitations of each technique. Besides the purely electromagnetic methods, a novel solution is proposed based on electromagnetic acoustic resonance (EMAR). This technique produces ultrasonic waves on the wire using electromagnetic transducers (EMAT) and is able to estimate the mechanical stress by measuring the frequency of the acoustic resonances. A new line shape calculation is proposed to the acoustic resonances of EMAR. Previously, the spectral data was fitted by a Lorentzian function. The new function is shown to be significantly superior, explaining features of the spectrum not previously described and achieving much better agreement with experimental data. Experiments with flexible pipelines show the viability of using EMAR to estimate the mechanical stress of the wires, even through the outer sheath in some circunstances. The limitations of this technique are discussed, along with possible forms of usage and the pending developments for its effective deployment on the field.