See Service Details

Tube failures are the leading cause of forced boiler outages affecting reliability and efficiency. Alstom's Materials Technology Center metallurgists perform in-depth investigations to determine the cause of tube failures.

ALSTOM delivers more than a metallurgical explanation. With each analysis, we provide useful definitive recommendations upon which our customers can act up to improve their stations' availability and to extend the life of power plant components. Complementing what we believe is the most comprehensive metallurgical service in the industry, ALSTOM's engineers understand boiler design, manufacturing and operations.

The result is a unique tube sample analysis service upon which ALSTOM's customers have come to rely.

Failure Analysis

All tubing failure analyses includes the following as a minimum:

• Visual examination characterizing the physical condition of the tubing to identify evidence of secondary damage that might suggest a particular failure mechanism
• Chemical analysis to verify conformance to the material specification and to detect compositional anomalies that could affect the serviceability of the tubing
• Preparation of metallographic specimen(s) so that macrostructral and microstructural features can be evaluated in the areas of interest
• Tubing hardness measurements and comparison to expected values as a basis for assessment of service induced degradation
• Evaluations of fracture surfaces using a scanning electron microscope and analysis if OD and ID deposits using Energy Dispersive Spectrometry (EDS) are included as required
• A formal report of the results including, where possible, the root cause of the failure and recommendations for corrective actions

Remaining Life Estimate

ALSTOM practices a specialized and proven approach for generating a remaining life estimate for steam-touched ferritic tubing.

Examination such as oxide scale measurements and the degree of carbide spheroidization provide only some of the inputs for ALSTOM's remaining life estimate. A detailed dimensional analysis specifically geared to detect evidence of swelling is used as a confirming or cross-check to ALSTOM-developed remaining life program estimates.

The combination of the two approaches, as well as ALSTOM's engineering judgment and understanding of boiler design, manufacturing, unit operation, maintenance practices and metallurgy provide superior remaining life estimates to customers.

ALSTOM also includes:

• A dimensional analysis including measurements of the OD, ID, wall thickness at multiple locations around the circumference and along the length of the tube sample
• Visual examination characterizing the physical condition of the tubing
• Chemical analysis to verify conformance to the material specification and to detect compositional anomalies that could affect the remaining life of the tubing
• Hardness testing
• Metallographic examination(s)
• Formal report

Serviceability Assessment

Water wall tubes, stainless steel steam-touched reheater and superheater tubes, and ferritic to stainless steel dissimilar metal welds (DMWs) are assessed for serviceability. Whether we are examining tubing from a time-dependent or time-independent region of the boiler, ALSTOM engineers weigh evidence of damage against multiple factors and influences before providing a rigorous assessment of the tube or DMW's serviceability.

Examples of the important factors ALSTOM takes into consideration include the operating environment, boiler design, time of service, cycling, fuel type, material type, and pressure/stress conditions.

As part of its assessment, ALSTOM performs the following analyses:

• Internal deposit analysis and density accumulation testing on waterwall tubes; chemical cleaning recommendations. Care is taken to note erosion/corrosion, pitting, or other damage mechanisms affecting serviceability.
• The variety of issues mentioned above in addition to wastage, scaling, creep cavities, swelling, etc. are taken into account when determining serviceability of stainless steel steam-touched reheater and superheater tubes.
• For ferritic to stainless steel dissimilar metal welds, the type of weld (pressure, induction or fusion), filler material, etc. are taken into account. The weld is examined for fissuring, micro-cracking and creep cavities.

ALSTOM also includes:

• Visual examination
• Dimensional analysis
• Chemical analysis
• Hardness testing
• Metallographic examination(s)
• A formal report including ALSTOM's assessment of serviceability

Increasing Your Competitive Edge

ALSTOM's Tube Sample Analysis Service is another example of the ALSTOM commitment to provide products and services to improve performance and reduce maintenance, with the goal of increasing your competitive edge. You can learn more about ALSTOM's Boiler Tubing capabilites by visiting our pressure parts website.