Creep life estimation of reformer alloy using 0-projection method- A neuro fuzzy approach

This paper deals with creep life assessment and deformation behavior of 11 years service exposed primary hydrogen reformer tube made up of HP40 grade of steel using the theta-projection method. Constant load creep tests have been performed at 870 degrees C under the stress range of 50-68 MPa. The generated creep data exhibit a sig-nificant amount of scatter under identical stresses. The existence of scatter in the creep deformation data leads to substantial amount of uncertainty in the estimation of theta-parameters and hence in the assessment of creep life. An adaptive neuro fuzzy based model is proposed to study the effect of variation of these parameters on creep life prediction. The model has been compared with the experimental findings.