Historically, boiler tube failures (BTF) have been the primary cause of loss of availability of fossil-fuel and combined cycle power plants and it remains a significant problem for the industry today. Implementation of a BTF prevention program has been proven to save the plant operators millions of dollars by just maintaining the availability of the plant. This 6-month-long project was conducted to identify guidelines for the best practice of BTF prevention. The study also addresses the factors that affect the performance and effectiveness of such programs. This report also includes a review and analysis of several BTF prevention programs from a number of worldwide conventional and CCGT (Combined Cycle Gas Turbine ) power plants. These serve as good examples to the reader to understand the effectiveness and implementation of such programs.
In general, the aim of the BTF program is to improve overall plant reliability through reduction in the number of boiler tube failures. A review of a number of BTF prevention programs from participating plants has revealed that some plants follow a well-documented BTF prevention program while others follow a step-by-step procedure to prevent boiler tube failures. It was observed that most of the BTF prevention programs/procedures studied included all important measures required for BTF management. After reviewing a number of BTF prevention programs from participating plants and other information from internationally available programs, best practice guidelines for a BTF prevention program have been developed in this project. Methodologies for the integration of the BTF prevention program into risk-based management have also been provided in this report. Even though most of the participating plants do have an approach that includes the measures required to prevent/ reduce boiler tube failures, the reliability performance varied from plant to plant. One of the main reasons for this may be lack of proper implementation of the program. A plant may possess a well-developed BTF prevention program, but its success depends on proper implementation and execution of the program. Some guidelines have been provided to show where most effort should be focused to enable a plant to have some measure of success in implementing the program and controlling BTF.
A section has been included in this report containing discussion on the important factors and issues related to BTF prevention. The report also provides detailed information on specific damage/failure mechanisms that affect various tube components of the boiler units and implementation of appropriate engineering solutions which is crucial to avoid repeat failures. The selection of appropriate tube materials with different grades from ASME/ASTM and European standards are also presented.
This detailed report has been divided into different sections to make it more readable. A large number of references have been provided at the end of each section for the reader to gain further background information if required.
Keywords:Tube, Conventional Boilers, Heat Recovery Steam Generator (HRSG) Boilers, Failure, Prevention, Materials, Damage Mechanisms, Risk Based Inspection (RBI), Metallurgical Investigation, Root Cause Failure Analysis, Guidelines