Life Assessments

Knowing the remaining useful operating life of your boiler, HRSG and associated balance-of-plant is a key parameter for effective management of your thermal power plant.

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A remaining life assessment (RLA) entails careful analysis to assess the impact that time and process conditions have had on the boiler and steam generation plant components up to the present time, and what the impact will be in the future based on projected operating scenarios. The components of greatest interest are the pressure parts(piping, vessels and boiler/HRSG tubing) but other areas such as casing and ductwork also need to be considered. In any life assessment, a detailed understanding of potential component degradation mechanisms is fundamental, as is accounting for how these are affected by the operation to date the and projected operating regime . Depending on the specifics of the unit, these mechanisms can include creep and creep-fatigue, fatigue and corrosion fatigue, flow-assisted corrosion (FAC), underdeposit corrosion, fireside attack and water & gas-side fouling.

If a boiler or HRSG are forced to move into cyclic or load-shifting operation due to changes in market conditions, this can invalidate the assumptions of the boiler’s original OEM design life assessment. At a minimum, it leads to greater challenges in managing the boiler pressure part integrity over the entire powerplant service life.

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The ageing of plant assets presents a real problem for owners and operators. The viability of future operation can be called in to question when a boiler or HRSG begins experiencing failures, reducing availability and the bottom line. The decision to run, re-rate, replace or retire is one that can only be answered by in-depth, cross-discipline analysis. In particular, the gap between engineering and economic questions can be difficult to bridge.
Tetra aims to address both questions by first understanding the degree of degradation to the pressure parts:

• Superheaters and Reheaters
• Evaporators and Waterwalls
• Drums
• Economisers and Preheaters
• Valves

The deliverable from the RLA study is a comprehensive report that provides a clear basis for planning inspections and repairs or replacements moving forward.

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Related Engineering & Analysis Services

Finite Element Analysis (FEA)

Finite Element Analysis (FEA) provides advanced analysis on HRSG components to determine the effects of fatigue, thermal stress and other associated occurrences and prevent losses in efficiency and/or failures.

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Fitness for Service

A fitness for service (FFS) evaluation is a process for assessing the structural integrity and safety of components that may have experienced damage and deterioration during their service life.

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Boiler Process Modelling and Simulation

Tetra Engineering provides a full-scope service for the modelling and operation analysis of all types of natural or forced circulation Power Boiler and HRSGs, including supercritical and once-through designs. This can be integrated into a full plant model to incorporate the steam turbine and steam cycle balance of plant.

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Flow Accelerated Corrosion Assessment (FAC)

Identify and prevent tube and pipe thinning caused by flow-accelerated corrosion (FAC) to avoid ruptures and leaks.

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Optimized NDE

Risk-based inspection (RBI) is an approach for ranking the priority of inspection and maintenance according to an assessed risk to the component or system integrity. One key aspect of any RBI program is to carefully select the locations for non-destructive examination (NDE) that are most susceptible to damage, according to the component's design and past and project operating mode, while considering the resources and time available during an upcoming inspection. Using multi-disciplinary experience and tools (thermal simulation, life assessment, structural calculations….) Tetra will help you get the most out of your NDE campaigns, by providing pre-outage planning, on-site supervision and post-inspection review.

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Root Cause of Failure (RCA)

Knowing the fundamental causes leading to failure is essential to mitigate the risk of the failure repeating. Tetra Engineering calls on an interdisciplinary team to assess the failure (or degradation) and determine the root cause.

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Performance & Efficiency Assessments

Services to help you evaluate how your operating performance has changed since the plant / boiler was commissioning, or to help you check the potential performance impact of planned modifications before they are implemented.

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