VERIFICATION OF REPAIR PAINTING EFFECT OF CORRODED WEATHERING STEEL BY EXPOSURE TEST

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Yuka Sugiyama ◽  
Toshihiko Aso ◽  
Atsumi Imai ◽  
Hiroaki Matsumoto
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Steel Surface ◽  
Steel Bridges ◽  
The Other ◽  
Weathering Steel ◽  
Water Leakage ◽  
Exposure Test ◽  
Repair Technique ◽  
Organic Zinc

Weathering steel generates dense protective rust on the steel surface. Since this protective rust would reduce corrosion speed, weathering steel can be used without any painting. Furthermore, the Life Cycle Cost of unpainted steel bridges would be lower than ordinary painted steel bridges. Due to these advantages, many weathering steel bridges have been constructed in recent years. Unfortunately, the generation of anomalous rust has been reported in some bridges, cause of water leakage or deicer. It is necessary to repair these bridges, but the repair technique for corroded weathering steel has never been established yet. This study aims to clarify the effect of various repair painting for corroded weathering steel by performing an exposure test. The exposure test has been carried out from September 2015 to Okinawa and Yamaguchi. Test in Okinawa is supplied airborne salt, and the test in Yamaguchi is not supplied airborne salt. Specimens, which produced anomalous rust, were repaired by 19 methods and exposed. As a result, it is effective to repair by organic zinc-rich paint in the area with airborne salt. On the other hand, it is appropriate to remove rust and salt on the steel surface by blasting in the area which is not supplied airborne salt.

Wide Gap Braze Repair Using Vertically Laminated Repair Scheme

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Doug Nagy ◽  
Xiao Huang
Keyword(s):  
Life Cycle ◽  
Intermetallic Compounds ◽  
Life Cycle Cost ◽  
Historical Development ◽  
Braze Alloy ◽  
The Other ◽  
Laminated Structure ◽  
Considerable Saving ◽  
The Past ◽  
Wide Gap

Repair of after-service gas turbine hot section superalloy components provides considerable saving in life-cycle cost of engines. Whereas a number of methods have been used in the past to repair these superalloy components, wide gap brazing technology has provided a practical alternative to repair difficult-to-weld alloys with substantial damages. In this paper, the historical development of wide gap repair technologies is reviewed first. Subsequently, the recent development in utilizing a vertically laminated structure to repair a large and deep gap (up to 16 mm) in one brazing cycle will be discussed. The microstructure resulted from this repair scheme will be evaluated and compared with conventional wide gap braze with slurry and that of the Liburdi powder metallurgy (LPM™) process. It is observed that in conventional wide gap brazing with premixed slurry, the presence of intermetallic compounds can be effectively reduced by reducing the ratio of braze alloy to gap filler, which, however, also contributes to the increased occurrence of macroscopic voids in the wide gap joint. The LPM™ method, on the other hand, can achieve a macroscopically void-free repair of gap (up to 6 mm) and minimize the formation of intermetallics. By using a vertically laminated repair scheme it is shown that the process is able to repair a deeper gap (up to 16 mm) with no macroscopic defects and reduced intermetallic compounds.

Life-cycle cost-effective optimum design of steel bridges

2004 ◽  
Vol 60 (11) ◽  
pp. 1585-1613 ◽  
Author(s):  
Kwang-Min Lee ◽  
Hyo-Nam Cho ◽  
Young-Min Choi
Keyword(s):  
Life Cycle ◽  
Optimum Design ◽  
Life Cycle Cost ◽  
Cost Effective ◽  
Steel Bridges

Wide Gap Braze Repair Using Vertically Laminated Repair Scheme

2008 ◽  
Author(s):  
Doug Nagy ◽  
Xiao Huang
Keyword(s):  
Life Cycle ◽  
Intermetallic Compounds ◽  
Life Cycle Cost ◽  
Historical Development ◽  
Braze Alloy ◽  
The Other ◽  
Laminated Structure ◽  
Considerable Saving ◽  
The Past ◽  
Wide Gap

Repair of after-service gas turbine hot section superalloy components provides considerable saving in life-cycle cost of engines. Whereas a number of methods have been used in the past to repair these superalloy components, wide gap brazing technology has provided a practical alternative to repair difficult-to-weld alloys with substantial damages. In this paper, the historical development of wide gap repair technologies is reviewed first. Subsequently, the recent development in utilizing vertically laminated structure to repair large and deep gap (up to 16 mm) in one brazing cycle will be discussed. The microstructure resulted from this repair scheme will be evaluated and compared to conventional wide gap braze with slurry and that of LPM™ process. It is observed that in conventional wide gap brazing with premixed slurry, the presence of intermetallic compounds can be effectively reduced by reducing the ratio of braze alloy to gap filler which however, also contributes to the increased occurrence of macroscopic voids in the wide gap joint. The LPM™ method, on the other hand, can achieve a macroscopically void-free repair of gap (up to 6 mm) and minimize the formation of intermetallics. By using a vertically laminated repair scheme it is shown that the process is able to repair a deeper gap (up to 16 mm) with no macroscopic defects and reduced intermetallic compounds.

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