A Re-Examination of Failure Analysis and Root Cause Determination

94. Visually examine the sample. Examine the sample with unaided eye, hand lensand/or low magnification field microscopes. Note the condition of the accessible surfacedocumenting all sorts of anomalies, searching for cracks, corrosion damage, thepresence of foreign material, erosion or wear damage, or evidence of impact or otherdistress. Also consider the condition of protective coatings. Manufacturing defects areimportant.If pipe failure is involved, it is important to carefully measure wall thicknesses both at thefailure site and some distance away from it at four locations 90 degrees apart aroundthe pipe circumference, starting a the failure site. At the same time note the presence ofany corrosion and map its general distribution.5. Identify defects Non-Destructively. Search for material imperfections withradiography, magnetic particle, ultrasonic, liquid/dye penetrant, eddy current, leak,and/or acoustic emissions non-destructive testing procedures. Some photographicexamples of these techniques are provided below.At Left: Magnetic Particle Testing done by inducing a magneticfield in a ferro-magnetic material and dusting the surface withiron particles. Above Center: Radiography. Above Right:Fluorescent Liquid Dye Penetrant viewed in black light.6. Conduct appropriate chemical analyses. Chemical analysis should be conductedon the original material to determine if the material was of proper type and grade,whether it met appropriate standards, and whether deviation from the specificationscontributed to the fracture, wear, breaks corrosion and failure. Wet chemical analysis,Atomic Absorption, X-ray Photoelectron, Auger Electron and Secondary Ion MassSpectroscopies are all potentially suitable methods of chemical analysis, depending onthe particular need of the situation. The techniques differ in important ways. Other partsof the failure “system” may also require analysis, including corrosion products, coatingsand liquids.