Recent Techniques for Life Assessment of Boiler Components

Gourishanker, S (2001) Recent Techniques for Life Assessment of Boiler Components. In: UNSPECIFIED.



Boiler components like headers, pipes and tubes operating at high temperatures-high pressures have only limited life due to the accumulation of creep damage during the normal /abnormal operating periods of the boiler. The rate of damage accumulation is to be assessed in these components in such a way that they do not lead to catastrophic consequences in the boiler, causing thereby loss of power generation and concomitant lower availability of steam generators. Although the methodology adopted for the assessment of residual creep life of high temperature headers is well defined, large number of techniques are employed to evaluate the damage rate, both on the base material and on the weldment. In addition to normal routine non-destructive methods,like ultrasonic testing, surface replication etc., a few advanced techniques like on-line strain monitoring by photogrammetry, post-exposure accelerated creeprupture test on miniature specimen, extricated from headers and shot punch tests are adopted. In the case of pipes, both destructive and non-destructive tests are carried out. Advanced techniques like Hardness Differential Method (HDM) and Replica Strain Monitoring (RSM) are developed to evaluate especially mid-life weldment cracking. The other advanced techniques are UT noise analysis, Magnetic Barkhausen Emission (BME) for damage assessment and Fibre-Optic-Remote-Monitoring-of-Structures (FORMS) for effective and cost-benefit analysis of critical piping systems. A host of techniques are available for estimating the remnant life of boiler tubes. A few off-line methods viz. Laser Shearography for detecting tube defects like erosion and corrosion, and ultrasonic measurement of internal steam side oxide scale thickness for creep damage assessment are practised. A new on-line monitoring technique, called Thin Layer Activation (TLA) is employed for measuring the rate and extent of tube metal erosion/corrosion. In this lecture, the above mentioned life assessment methods and prediction procedures will be dealt extensively.

Item Type:Conference or Workshop Item (UNSPECIFIED)
Uncontrolled Keywords:Replica Strain Monitoring
Divisions:Material Science and Technology
ID Code:2771
Deposited By:Sahu A K
Deposited On:19 Apr 2011 21:44
Last Modified:13 Jan 2012 12:06
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