A method is developed to nondestructively estimate stresses in bent pipes using a magnetic anisotropy sensor. The values measured by the magnetic method contain both stresses generated during manufacture and by external loads.Out-of-plane bending test and in-plane bending test using a mandrel elbow were performed. The values obtained by the magnetic method were regressed to Rodabaugh & George's theoretical equation for a bent pipe. From the regression curve obtained, it was possible to obtain the external moment that was purely applied to the bent pipe. The stress range where measurement is possible is smaller than that in a straight pipe, because the residual stress is greater than that of a straight pipe. If the theoretical stress calculation equation by Rodabaugh & George was used, it was possible to separate the residual stress from the stress produced by the external load, based on the magnetic method due to inplane bending and out-of-plane bending.

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