[en] The report describes the execution of a strain gage plan to determine fit-up stress levels in a bypass line in the recirculation system of a boiling water reactor. In addition to the experimental work, an analysis method is developed to determine the forces and moment acting throughout the line using the results from a limited number of strain gage locations. The general level of stress measured and calculated in the line was low. The peak axial strain measured with strain gages gave a tensile stress of 2.3 ksi at the outlet-side weldolet. The analysis showed that the maximum calculated axial stress in the line occurred at the inlet-side elbow with a magnitude of 4.3 ksi. This level of stress is the sum of construction fit-up and dead weight and is not significant when compared with total stress levels in BWR bypass lines from service-induced and residual welding stresses