To demonstrate the viability of the newly developed ferritic materials P92 and P122, a fabrication and installation trial was made in parallel to the construction of a coal fired USC boiler at ELSAM in Denmark. In the boiler, designed for steam parameters 290 bar/580°C/580°C/580°C, three out of 28 superheater outlet collectors, otherwise made of P91, were replaced by two collectors of P92 and one of P122. The Danish authorities accepted the demonstration project under the following conditions: 1. Collector design should be in accordance with the ASME Boiler and Pressure Vessel Code, Section 1, using materials properties for P92 and P122 given in ASME Boiler and Vessel Code Cases 2179 and 2180 respectively. 2. Fabrication of the collectors should be in accordance with "Danish Power Companies' Joint Conditions for Welding on Pipe Systems" 3. Welding procedure, Procedure Qualification and Welder Qualification to be witnessed by third body inspector before approval by the Danish authorities 4. Final quality control of the collectors - NDT, heat treatment and hydrostatic testing - to be witnessed by third body inspector before approval by the Danish authorities. 5. Inspection of the collectors including NDT on specified welds every two years after commissioning. The collectors were manufactured and approved by the Danish authorities, and finally installed in the boiler in 1998 where they have been in service without any problems since the commissioning of the power plant. The results from the first on site NDT inspection after two years in service did not reveal any sign of crack initiation or structural degradation in or adjacent to the welds.
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