Life assessment of boiler pressure parts. Volume 7, Life assessment technology for superheater/reheater tubes: Final report

Technical Report · Mon Nov 01 04:00:00 EST 1993

OSTI ID:10132004

Grunloh, H J; Ryder, R H ^[1]

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1. General Atomics, San Diego, CA (United States)

The severe environment in which superheater and reheater tubes operate can lead to premature failure by the interaction of possible damage mechanisms. One such mechanism, creep-rupture, has been studied extensively and the means of measuring the extent of such damage and the methods of assessing its effects on the remaining service life of superheater/reheater tubes are the subjects of this volume. A study was initially performed to identify techniques in current use in industry for measuring parameters that are pertinent to the creep-rupture damage mechanisms. A plan was implemented to apply these techniques in the field, at two selected host utility boilers, and in the laboratory. The field studies included tracking failure histories, assembling representative sets of plant operating data, installing inlet and outlet pad-type thermocouples, designing and installing in-furnace chordal-type thermocouples, conducting component-wide steamside oxide and tube wall thickness surveys, and selecting and extracting tube samples for laboratory evaluations. The laboratory studies included metallographic measurement of steamside oxide and tube wall thicknesses, accelerated creep-rupture testing, including tube burst tests and miniature uniaxial creep-rupture tests, and ultimate tensile strength testing. Evaluations on the use of ultrasonic methods for measuring oxide and tube wall thickness are offered, newly-developed creep-rupture life and creep strain rate models are presented, and recommendations are made concerning the optimal stress formula for use in damage assessment and remaining life calculations. Recommendations are made for use of an integrated application of inspection and calculational methods incorporating simplified probabilistic techniques to efficiently conduct component-wide evaluations.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (United States); General Atomics, San Diego, CA (United States); Babcock and Wilcox Co., New Orleans, LA (United States)
• Sponsoring Organization: Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 10132004
• Report Number(s): EPRI-TR--103377-V7; ON: UN94007943
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200104
36 MATERIALS SCIENCE
360105
BOILERS
COMPONENTS
CORROSION AND EROSION
CORROSION FATIGUE
CREEP
FOSSIL-FUEL POWER PLANTS
IN-SERVICE INSPECTION
OXIDATION
SERVICE LIFE
SUPERHEATERS
TUBES