Life assessment of high temperature headers

摘要

High temperature superheater and reheater headers have been a necessary focus of any boiler life extension project done by the electric utilities. These headers operate at high temperatures in excess of 900 deg F and are subject to thermal stresses and pressure stresses that can lead to cracking and failure. Babcock & Wilcox Company's investigation of these problems began in 1982 focusing on P11 materials (1~1/4Cr-~1/2Mo). Early assessment was limited to dimensional analysis methods which were aimed at quantifying swell due to creep. Condition assessment and remaining useful life analysis methods have evolved since these initial studies. Experience coupled with improved inspection methods and analytical techniques has advanced the life assessment of these hgih temperature headers. In the discussion that follows we will porovide an overview of B&W's approach to header life assessment including the location and causes for header failures. Inspection techniques and analysis methods which are all directed at determining the remaining useful life of these high temperature headers.