The MOC of tube is TU 15 CD 205 .The service life of tube is 7 years before failure. The steam temperature & pressure of tube are and 450?C and 140 kg/cm2 respectively. The tube has OD 63.5mm and ID 5.5mm. Tubes are located horizontally with flue gas passes vertically.
Scanning Electron Microscopy (SEM): Upon SEM examination conducted by engineers at TCR, it revealed presence of inter-granular cracks and presence of numerous creep cavities at grain boundary. Presence of micro-cracks are observed more towards outer surface and near by crack region. Severity of cracks and cavity reduces when we move away from the main crack.
Microstructure Examination: Crack displayed inter-granular nature of propagation with many small parallel cracks adjacent to main crack is observed. This maginification was done at the TCR Engineering laboratory using a Leco Image Analyser at 300X.
In present case the failure of tube seems to have occurred due to long term over- heating, above allowable design temperature, could be due to higher velocity of flue gas at this region or impingement of flue gases on tube surface facing flue gas or improper steam flow.
In a bottom fired furnace tube failure have experienced service of 14 months against the normal life of 6 to 7 yrs. MOC of tube is 25 Cr/35 Ni. The average tube metal temperature remains between 1000 to 1100 ºC temperatures. As per the manufacturer data, these tubes are designed for 1150ºC. The pressure inside the tube is 1 kg/cm2 g.
Scanning Electron Microscopy (SEM): SEM analysis conducted by failure investigation team from TCR Engineering revealed a progressive nature of fracture especially towards OD side.
However, majority evidences on fracture surface were masked under heavy scaling, which is generally expected under such service.
Microstructure Examination: The crack is associated with carburizing more so at outer surface with decreasing the depth of carburizing towards ID. Another important evidence of crack originating from outer diameter and progressing towards ID. This maginification was done at the TCR Engineering laboratory using a Leco Image Analyser at 300X.
In present case the failure of tube has occurred due to localized overheating, which reduced ductility and failed under operational vibrations. TCR recommends looking in to the possibility of development of high temperature at the time of decoking operation.
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Upon SEM examination conducted by engineers at TCR, it revealed presence of inter-granular cracks and presence of numerous creep cavities at grain boundary. Presence of micro-cracks are observed more towards outer surface and near by crack region. Severity of cracks and cavity reduces when we move away from the main crack.
Crack displayed inter-granular nature of propagation with many small parallel cracks adjacent to main crack is observed. This maginification was done at the TCR Engineering laboratory using a Leco Image Analyser at 300X.
SEM analysis conducted by failure investigation team from TCR Engineering revealed a progressive nature of fracture especially towards OD side. 
The crack is associated with carburizing more so at outer surface with decreasing the depth of carburizing towards ID. Another important evidence of crack originating from outer diameter and progressing towards ID. This maginification was done at the TCR Engineering laboratory using a Leco Image Analyser at 300X.
After 8-years of useful service life, a steam turbine was reported to have been working with abnormal vibrations. When turbine was opened five blades of 8th stage were found in broken condition from the root. Steam turbine operates with steam temperature of 770?F & working pressure at 568.3 Psi. 
Fracture surface kept under SEM show multiple origins of the fracture and clearly shows progressive mode of failure. Fig. suggest rubbing of the metal surface where the failure had occurred. 
Low magnification examination was done by the failure Analysis and Investigation team from TCR Engineering to find out the corrosion characteristics. Internal surface of pipe, weld and elbow showed severe corrosion on pipe. The close-up view of corroded surface inside the pipe show effect of general corrosion and flow pattern. Leakages observed in the form of openings between weld and pipe.
Uniform dissolution at ID is observed under microstructure examination at a magnification of 300x at the TCR Engineering laboratory in India.
Premature failure of integral pinion shaft was reported at a cement mill. The shaft failed after service life of approximately 15,000 hours (625 days) against intended design life of 30 years. The shaft is made from EN 10083-1 (1991) 30CrNiMo8 with through hardened and tempered to achieve 310-335 BHN. The shaft rotates at 133 to 134 RPM. The failure of the shaft noticed in form of cracks. Cracks were observed at 45deg to the longitudinal axis of shaft. 
Fracture surface at thread region shows relatively flat fracture whereas further fracture shows brittle nature with chevron marks. Fracture surface below thread region at keyway disclosed multiple ridges with relatively coarse fatigue striations.
SEM done by TCR Engineering revealed intergranular fracture with intergranular cracks. A fracture is brittle and shows inter-granular mode. Presence of fine cracks is observed.
Microstructure examinations at various section reveled that, general condition of shaft is in hardened and tempted condition. Further microstructure revealed presences of inter-granular cracks. The cracks are moving on prior austenitic grain boundaries and are observed filled with oxides. Presence of oxide inside the cracks is most important evidence in present case. This was done at a magnification of 560X at the TCR Engineering Services laboratory.