Archives du mot-clef Failure analysis

Failure analysis of copper tube

Publié le par
Répondre

A new interesting paper in « Engineering Failure Analysis » published on ScienceDirect.com. This paper reports the failure analysis of a leaked copper tube used in a refrigerating plant for carrying polyol ester oil for lubrication and cooling of compressor bearings. Failure had occurred at the bent region of the tube in the form of a wide diametric crack.

More information : Failure analysis of copper tube used in a refrigerating plant.

Stress corrosion cracking in 316L stainless steel

Publié le par
Répondre

A new interesting paper in « Case studies in Engineering Failure Analysis » published on ScienceDirect.com.

There were three consecutive occurrences of bellows failure in a particular pressure safety valve (PSV) of a petroleum refinery within a time span of one week. The bellows were made of 316L grade austenitic stainless steel, and the PSV was mounted on one of the vessels of vacuum gas oil service in a hydrocracker unit. Metallurgical analysis of the failed bellows revealed that the failure had occurred by stress corrosion cracking (SCC). This paper brings out the detail of investigation carried out.

Validation of F-16 Wing Attachment Fitting bolts

Publié le par
Répondre

A new paper in  « Engineering Failure Analysis » published on ScienceDirect.com.

During a modification programme, the Wing Attachment Fitting (WAF) cadmium-plated steel bolt assemblies from 33 F-16 aircraft were cleaned in a non-approved chemical solution, a paint stripper. This removed much of the cadmium plating, leading to in-service superficial rusting of some bolt ends and nuts. The OEM and chemical manufacturer became concerned about possible hydrogen embrittlement of the bolts owing to exposure to the paint stripper. This paper brings out the detail of investigation carried out.

Failure analysis of a martensitic stainless steel roll

Publié le par
Répondre

Sciencedirect.com report an article published in « Engineering Failure Analysis » : the failure analysis of a martensitic stainless steel (CA-15M) roll manufactured by centrifugal casting and used in cast glass rolling was carried out. The crack propagation began in the internal surface of the roll. Tensile thermal stresses in the internal surface of the roll associated with microstructural embrittlement (network of interfacial carbide and porosities) are thought to be the main causes for the premature failure of the roll. Finally, materials selection was performed to replace the CA-15M stainless steel with another class of stainless steel for centrifugal casting.

Failure analysis techniques for a 3D world

Publié le par
Répondre

The proliferation of advanced IC package configurations is driving the need for new tool failure analysis (FA) tool development. Although scientists and engineers in the semiconductor industry developed new tools and techniques based on Moore’s Law, with its need to analyze ever-smaller devices, the advent of three-dimensional packaging schemes requires new tools. In this paper they quickly review the existing tools used for package-level FA and introduce several new techniques that aid with this type of analysis. They also discuss the problems and challenges moving forward for this type of tool development.

Cracking of an austenitic stainless steel lance pipe

Publié le par
Répondre

Kiln of a lime plant, a part of an integrated steel plant, converts limestone (CaCO3) into lime (CaO) by heating at a temperature of around 900 °C using coke oven gas as a fuel. Coke oven gas is a by-product of the coke plant, which contains mainly hydro-carbons. The coke oven gas is lanced into the kiln through a number of pipes attached to the kiln. The lance pipes are cracking prematurely within 6 months of their service against an expected service life of 3 years.  The analysis of cracking of the lance pipe is presented in this article. It will be published in Engineering Failure Analysis in December 2013.

More information at : Cracking of an austenitic stainless steel lance pipe in a lime calcining plant.

Delamination and discoloration of photovoltaic module

Publié le par
Répondre

Discoloration and delamination (D&D) of encapsulant in a photovoltaic (PV) module affect the electrical characteristics. Therefore, in this study D&D-induced degradations are investigated with a 25-year-old PV module. The average power output of 25-year-old PV modules decreased by 17.9% compared to initial value. However, insulation properties have been stable over 25 years. Electroluminescence image shows that discoloration has an effect on the cell degradation. The effect of D&D on the light reflectance and transmittance is evaluated by performing a trapezoidal integration with the standard global reference spectrum. Failure analysis reveals that delamination occurs at the interface between encapsulant and solar cell and also shows that corrosion of solder occurred near delamination site

More at :http://www.sciencedirect.com/science/article/pii/S0026271413002370?np=y

Il s’agit d’un article présenté au Symposium européen sur la fiabilité des Electron Devices, Physique et analyse de défaillance

Service fatigue cracking in an aircraft bulkhead exposed to a corrosive environment

Publié le par
Répondre

 

This paper presents a supporting case study that examines fatigue cracks that were detected in an F/A-18 Hornet bulkhead during post-service testing and teardown. The in-service phase of the cracking had significant evidence of oxidation on their surfaces which indicated an exposure to a mildly corrosive environment. Both the service and laboratory phases of the cracking were the subject of quantitative fractography and estimates of the crack growth rates were made. A comparison of the in-service and the in-test phases of crack growth indicated that no notable effect on the service part of the fatigue crack could be attributed to its exposure to the service environment.

Read the article on http://www.sciencedirect.com

Failure analysis of solenoid valve components

Publié le par
Répondre

Valve had failed as a result of particles of material becoming trapped between the valve seat recess and the valve seat ball, leading to erosion of the valve seat recess, valve seat ball and the valve operating pin; this allowed hydraulic fluid to flow when the valve was nominally in the de-energised position.The material of construction of the valve seats was not compliant with engineering drawings.The investigation demonstrated the importance of maintaining the cleanliness of hydraulic systems and of the need to control the materials of manufacture in safety critical applications.

Read more at : Failure analysis of solenoid valve components from a hydraulic roof support.

Corrosion of Flue Gas Sensor in Boiler Stack

Publié le par
Répondre

A commercial gas velocity sensor used for flue gases monitoring was subject to severe corrosion failure. A combination of mechanisms was proposed including a dominating 5 severe dew point corrosion for both transducer and its covering, galvanic attack and an eventual hydrogen attack for the transducer side part. Recommendations were proposed to avoid a future severe damage to such type of sensor including an insulation between transducer and covering metals and an up-grade of the titanium alloy used.

More information : sciencedirect.com/science/article