Analysis of floating-head heat exchanger bolts failure
Authors
Gligorijević, Bojan R.Katavić, Boris T.
Alil, Ana
Jegdić, Bore V.
Ristić, Marko
Prokolab, Milan
Conference object (Published version)
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As-received floating-head heat exchanger bolts were broken (BB) and deposite-coated. The aim was to estimatea cause of their failure. The new bolts of the same material were used as a reference material (reference bolt –RB). After visual and radiographic examination, their chemical composition, structure and room-temperaturemechanical properties were determined and compared. Comparison was made with the values set by standard,as well. Afterwards, fractography was performed on fractured surfaces of tensile specimens and originally(during exploitation) BBs to try to get an impression about bolts failure mechanism. Qualitative analysis ofdeposite was employed in order to confirm was there any possible influence of surroundings during their failurein terms of corrosion-assisted cracking. Chemical composition of RB and BB materials was analyzed by use ofspectrophotometry and structure properties with light optical microscope (LOM). Fractured surfaces of tensilespecimens and of BBs, as well ...as deposite chemistry, were analyzed by use of Scanning Electron Microscopywith Energy Dispersive System (SEM-EDS). BBs had an approximately three times higher sulphur content andlesser manganese content, lower ductility and higher strength values comparing to those of the RBs. Generally,fracture surfaces of both, RB and BB tensile specimens have a similar rosette-like macro-appearance. The onlydifference is that the radial marks in the case of the RBs are rougher. The surface has a more fibrous area andshear lip presence. Fracture mode can be characterized as dimple rupture and micromechanism as microvoidcoalescence. In the case of BB tensile specimens, the mixed presence of dimples and cleavage facets wasnoticed. The macrofractography of originally broken surfaces shows a rough and complex topography offracture surfaces indicating on a possibility that bolts failure has been a result of complex loading conditions.Presence of sulphur- and chlorine-containing particles on the fracture surfaces of BBs and in deposite reveals apossibility that failure was environmentally-assisted.
Keywords:
bolts / chemical and structure analysis / mechanical testing / SEM-EDS / fracture mechanismSource:
Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania, 2011, 1-9Publisher:
- Timisoara, Romania : SUDURA publising house
Funding / projects:
- Investigation and Optimization of the Technological and Functional Performance of the Ventilation Mill in the Thermal Power Plant Kostolac B (RS-MESTD-Technological Development (TD or TR)-34028)
Institution/Community
IHTMTY - CONF AU - Gligorijević, Bojan R. AU - Katavić, Boris T. AU - Alil, Ana AU - Jegdić, Bore V. AU - Ristić, Marko AU - Prokolab, Milan PY - 2011 UR - https://cer.ihtm.bg.ac.rs/handle/123456789/7500 AB - As-received floating-head heat exchanger bolts were broken (BB) and deposite-coated. The aim was to estimatea cause of their failure. The new bolts of the same material were used as a reference material (reference bolt –RB). After visual and radiographic examination, their chemical composition, structure and room-temperaturemechanical properties were determined and compared. Comparison was made with the values set by standard,as well. Afterwards, fractography was performed on fractured surfaces of tensile specimens and originally(during exploitation) BBs to try to get an impression about bolts failure mechanism. Qualitative analysis ofdeposite was employed in order to confirm was there any possible influence of surroundings during their failurein terms of corrosion-assisted cracking. Chemical composition of RB and BB materials was analyzed by use ofspectrophotometry and structure properties with light optical microscope (LOM). Fractured surfaces of tensilespecimens and of BBs, as well as deposite chemistry, were analyzed by use of Scanning Electron Microscopywith Energy Dispersive System (SEM-EDS). BBs had an approximately three times higher sulphur content andlesser manganese content, lower ductility and higher strength values comparing to those of the RBs. Generally,fracture surfaces of both, RB and BB tensile specimens have a similar rosette-like macro-appearance. The onlydifference is that the radial marks in the case of the RBs are rougher. The surface has a more fibrous area andshear lip presence. Fracture mode can be characterized as dimple rupture and micromechanism as microvoidcoalescence. In the case of BB tensile specimens, the mixed presence of dimples and cleavage facets wasnoticed. The macrofractography of originally broken surfaces shows a rough and complex topography offracture surfaces indicating on a possibility that bolts failure has been a result of complex loading conditions.Presence of sulphur- and chlorine-containing particles on the fracture surfaces of BBs and in deposite reveals apossibility that failure was environmentally-assisted. PB - Timisoara, Romania : SUDURA publising house C3 - Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania T1 - Analysis of floating-head heat exchanger bolts failure SP - 1 EP - 9 UR - https://hdl.handle.net/21.15107/rcub_cer_7500 ER -
@conference{ author = "Gligorijević, Bojan R. and Katavić, Boris T. and Alil, Ana and Jegdić, Bore V. and Ristić, Marko and Prokolab, Milan", year = "2011", abstract = "As-received floating-head heat exchanger bolts were broken (BB) and deposite-coated. The aim was to estimatea cause of their failure. The new bolts of the same material were used as a reference material (reference bolt –RB). After visual and radiographic examination, their chemical composition, structure and room-temperaturemechanical properties were determined and compared. Comparison was made with the values set by standard,as well. Afterwards, fractography was performed on fractured surfaces of tensile specimens and originally(during exploitation) BBs to try to get an impression about bolts failure mechanism. Qualitative analysis ofdeposite was employed in order to confirm was there any possible influence of surroundings during their failurein terms of corrosion-assisted cracking. Chemical composition of RB and BB materials was analyzed by use ofspectrophotometry and structure properties with light optical microscope (LOM). Fractured surfaces of tensilespecimens and of BBs, as well as deposite chemistry, were analyzed by use of Scanning Electron Microscopywith Energy Dispersive System (SEM-EDS). BBs had an approximately three times higher sulphur content andlesser manganese content, lower ductility and higher strength values comparing to those of the RBs. Generally,fracture surfaces of both, RB and BB tensile specimens have a similar rosette-like macro-appearance. The onlydifference is that the radial marks in the case of the RBs are rougher. The surface has a more fibrous area andshear lip presence. Fracture mode can be characterized as dimple rupture and micromechanism as microvoidcoalescence. In the case of BB tensile specimens, the mixed presence of dimples and cleavage facets wasnoticed. The macrofractography of originally broken surfaces shows a rough and complex topography offracture surfaces indicating on a possibility that bolts failure has been a result of complex loading conditions.Presence of sulphur- and chlorine-containing particles on the fracture surfaces of BBs and in deposite reveals apossibility that failure was environmentally-assisted.", publisher = "Timisoara, Romania : SUDURA publising house", journal = "Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania", title = "Analysis of floating-head heat exchanger bolts failure", pages = "1-9", url = "https://hdl.handle.net/21.15107/rcub_cer_7500" }
Gligorijević, B. R., Katavić, B. T., Alil, A., Jegdić, B. V., Ristić, M.,& Prokolab, M.. (2011). Analysis of floating-head heat exchanger bolts failure. in Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania Timisoara, Romania : SUDURA publising house., 1-9. https://hdl.handle.net/21.15107/rcub_cer_7500
Gligorijević BR, Katavić BT, Alil A, Jegdić BV, Ristić M, Prokolab M. Analysis of floating-head heat exchanger bolts failure. in Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania. 2011;:1-9. https://hdl.handle.net/21.15107/rcub_cer_7500 .
Gligorijević, Bojan R., Katavić, Boris T., Alil, Ana, Jegdić, Bore V., Ristić, Marko, Prokolab, Milan, "Analysis of floating-head heat exchanger bolts failure" in Proceedings of the 9th International Conference “Structural integrity of welded structures”, 03-04.11.2011, Timisoara, Romania (2011):1-9, https://hdl.handle.net/21.15107/rcub_cer_7500 .