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ML00170 - Sep.2020

MIC in Aluminum Brass Tubes

Micrography of a transverse section of the tube, close to the leakage point. The thickness is localized reduced where the internal passive layer was ruptured, and the chemical effect of the biological proliferation created a high corrosion rate.

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of a of the , close to the point. The thickness is localized reduced where the internal passive layer was ruptured, and the chemical effect of the biological proliferation created a high rate.
M

Material

Aluminum Brass
  • UNS C68700
Ds

Description

Several that were operating during 6 years in a marine (seawater in the tube and steam in the shell) had suffered from the internal side of the tubes. The mechanism is a localized dissolution with caused by (MIC).

C

Chemistry (% in weight)

Tube analysis

75.6Cu; 21.5Zn; 0.01Fe; 0.034Sn; 2.2Al; 0.005As.

Associated Images
Visual aspect of the internal side of the tube, after longitudinal cut, presenting the region of leakage. The tube, that is 1.6mm thick, presented several points of localized diissolution .
457
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface AspectDf - Localized Thinning
Macrography of a transverse section of the tube close to the leakage point, evidencing a localized thinning from the internal side of the tube.
65
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Localized Thinning
Visual aspect of the internal side of the tube, after longitudinal cut, presenting regions where the internal layer is fully stained.
55
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Aspect Before AnalysisDf - Internal Surface
Detailed aspect, by a low magnification microscope, of the internal side of the tube, after longitudinal cut. The tube, that is 1.6mm thick, presented several points of localized corrosion leading to leaks.
46
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface AspectDf - Localized Corrosion
Uniform granular microstructure of the aluminum brass, monophasic alpha.
44
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Alpha
Micrographic detail of the granular structure of the aluminum brass, monophasic alpha.
44
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Alpha
Detailed aspect, by a low magnification microscope, of the internal side of the tube with deposits.
36
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface AspectDf - Internal Surface
Scanning electron microscopy of the internal surface of the tube, showing that under the deposits there are regions of localized corrosion.
30
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface Aspect by SEMDf - Internal Surface
Microscopic detail, by scanning electron microscope, of a region where there is a localized dissolution at the internal surface of the tube. The deposits are adhered at the surface and under the deposits, the analysis indicated increased sulfur levels, suggesting SRB (sulfate reduced bacteria) effects.
31
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface Aspect by SEMDf - Pitting
Scanning electron microscopy aspect of the region inside of a pit. The aspect is of a chemical attack, generated by the metabolic by-products of the adhered microorganism. The effect is of a localized dissolution and the granular tube microsctruture is revealed.
40
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Surface Aspect by SEMDf - Corrosion
Micrography of a transverse section of the tube, close to the leakage point. The thickness is localized reduced where the internal passive layer was ruptured, and the chemical effect of the biological proliferation created a high corrosion rate.
26
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Localized Thinning
Micrography of a transverse section of the tube at the localized reduced thickness point. Close to the internal surface.
28
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Internal Surface
Micrographic detail of a transverse section of the tube at the localized reduced thickness point. Close to the internal surface.
26
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Internal Surface
Macrograhy of
5
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - Transverse Section AspectDf - Localized Thinning
MIC in Aluminum Brass Tubes
2
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Localized Corrosion
MIC in Aluminum Brass Tubes
2
VIEW
ML00170 / Sep.2020
MIC in Aluminum Brass Tubes
M - Aluminum BrassP - Seamless tubeAp - MaritimeCd - Preferential Dissolution
Cm - FeCl3+HCl+Ethanol Etched MicroDf - Close to the Internal Surface