Enabling you to identify and mitigate the intrinsic risk in your operations, supply chains and business processes.
Evaluating how your products and services meet and exceed quality, safety, sustainability and performance standards.
Validating the specifications, value and safety of your raw materials, products and assets.
Tube Sample Analysis
This blog is the second in a series discussing boiler tube condition assessments. While these basics might be familiar to many, this second installment will serve as a refresher to the experienced and an introduction to novices. Tube failures, which range from pinhole leaks to ruptures, require shutting down a boiler to repair. Once the failed section has been cut out and replaced and the boiler restarted, the first question which should come to mind is, "Why did the tube fail?" The most effective method of determining the failure mechanism is to perform a metallurgical analysis.
What should you expect from this analysis? The results are partly under your control, i.e., sample preparation. Here are a few things which you can do to ensure successful analysis:
Typically, the laboratory will utilize the following techniques:
Additional or alternative techniques may be used on an as-needed basis. The analysis will determine the failure mechanism, but will seldom identify the root cause. Additional measures, typically involving instrumentation monitoring or operating history review, are required to determine the condition(s) responsible for the failure.
The report should provide the failure mechanism, potential root cause(s), and recommendations for future actions to determine root cause(s) and prevent failures.
Once the report is received and reviewed, it's important to not just put the report away and move onto the next project. The results should be input into the plant data management software, such as Intertek's AWARETM software. If the plant does not have this type of software, consider installing it. Historical records are an important part of moving from a reactive maintenance program (i.e., replacing tube failures as they occur) to a preventative or proactive maintenance program (using examination techniques such as TubeAlert to determine the current condition and future examination intervals), and allows for maintenance or replacement activities during planned as opposed to forced outages.
For additional information on tube samples, contact the author or Henry Vaillancourt at firstname.lastname@example.org (408) 636-5382.
Clayton Q. Lee, Director, Thermal Engineering, Intertek Asset Integrity Management (AIM). The author has over thirty years of experience consulting to the power industry in the areas of heat transfer, fluid mechanics, stress analysis and fracture mechanics. He has authored several sponsored applied research reports used by the power industry.