Erosion-corrosion in a very localized section -6 in(152 mm) x 3 in (76mm) -of two bottom Ubends of a reformer heater led to leakage and subsequent fire damage. The 6.625 in diameter (168 mm) x 0.321 in (8 mm) wall 1 1/4Cr - 1/2 Mo steel tubes were in service for 25 years. The two affected tubes ID’s were in the SE coil section. Visual and metallurgical analyses did not reveal any signs of long term creep darnage or overheating. Normal ultrasonic thickness measurements taken during shutdowns did not detect the damage that was located at or just below the refractory interface. The melted rundown material observed in the tubes and headers was identified as extraneous metal fines. Limited thickness data showed no apparent problems with the top and bottom headers or the other three coils. Sections of the fbrnace tubes were selected for visual and life assessment analyses. Inspection plans, procedures and process flow analyses were provided to help identify trouble spots. Techniques utilized to prioritize and schedule tube replacements for similar furnaces in the unit are discussed. Keywords – Reformer, Heater Tube, U-Bend, Erosion-Corrosion, 1 1/4Cr - 1/2 Mo steel