Analysis of cracking of co-extruded recovery boiler floor tubes

Conference · Fri Aug 01 04:00:00 EDT 1997

OSTI ID:527887

Keiser, J R; Taljat, B; Wang, X L ^[1]

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1. and others

Cracking of the stainless steel layer in co-extruded 304L/SA210 tubing used in black liquor recovery boilers is being found in an ever-increasing number of North American pulp and paper mills. Because of the possibility of a tube failure, this is a significant safety issue, and, because of the extra time required for tube inspection and repair, this can become an economic issue as well. In a project funded by the U.S. Department of Energy and given wide support among paper companies, boiler manufacturers, and tube fabricators, studies are being conducted to determine the cause of the cracking and to identify alternate materials and/or operating procedures to prevent tube cracking. Examination of cracked tubes has permitted characterization of crack features, and transmission electron microscopy is providing information about the thermal history, particularly cyclic thermal exposures, that tubes have experienced. Neutron and x-ray diffraction techniques are being used to determine the residual stresses in as-fabricated tube panels and exposed tubes, and finite element modeling is providing information about the stresses the tubes experience during operation. Laboratory studies are being conducted to determine the susceptibility of the co-extruded 304L/SA210 tubes to stress corrosion cracking, thermal fatigue, and corrosion in molten smelt. This paper presents the current status of these studies. On the basis of all of these studies, recommendations for means to prevent tube cracking will be offered.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 527887
• Report Number(s): CONF-971060--1; ON: DE97007761
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BOILERS
CRACK PROPAGATION
PAPER INDUSTRY
SPENT LIQUORS
STAINLESS STEEL-304L
STRESS CORROSION
THERMAL FATIGUE
TUBES