Community Research and Development Information Service - CORDIS


During recent years cracking of AISI 304L type composite floor tubes in recovery boilers has been a subject of active research both in North America and in Scandinavia. The first reports concerning composite floor tube cracking came into public in late 1980s in Scandinavia and already in the early 1990s it was recognised that the composite tube cracking was a widespread problem throughout the pulp and paper industry.

Cracks typically initiate in the stainless steel cladding and penetrate through the cladding to the stainless steel/low alloy steel interface, where the cracks normally grow along the interface and do not penetrate into the low alloy steel. This kind of corrosion problems may exist in addition to floor tubes also in air ports and smelt spout openings. Most failure analyses support environment assisted cracking (EAC) mechanism although thermal fatigue (TF) failures have also been observed.

This paper summarises current knowledge concerning the thermal, environmental, mechanical and metallurgical effects on cracking phenomena. Attention is paid to the possibility for mitigation of the recovery boiler failures with new alternative materials. ls.

Additional information

Authors: POHJANNE P, VTT Manufacturing , VTT (FI);MKIP M, VTT Manufacturing , VTT (FI);OKSA M, VTT Manufacturing , VTT (FI);SAARINEN P, Helsinki University of Technology. Laboratory of Engineering Materials, (FI);HNNINEN H, Helsinki University of Technology. Laboratory of Engineering Materials, (FI)
Bibliographic Reference: An oral report given at: Baltica V-2001, International Conference on Condition & Life Management for Power Plants. Held in: Porvoo Finland, 6-8 June, 2001
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