Question

CET 345W Materials Testing Laboratory

1. To Research for NDT cases online. To find one case where magnetic particle testing was used and one where liquid penetrant was used.
2. To discuss why we think each method is more appropriate for each case

Answer 1

Ans 1) Case for Magnetic particle testing is :

Magnetic particle testing on a pipe line to check stress corrosion cracking .

Case for liquid penetrant testing is :

Liquid penetrant testing on iron to detect forging, welding surface defects, surface porosity and fatigue cracks

Ans 2)   Magnetic particle testing is done on a pipe line to check stress corrosion cracking because MPI reveal cluster of black lines .Cracks which are normally invisible are visible after MPI because of magnetic particle clustering at the crack opening .Hence, this method is quick and suitable for inspection and testing of pipeline for corrosion cracking

   Liquid penetrant test is performed on iron or any material like metals,plastic and ceramics to detect forging, welding surface defects, surface porosity and fatigue cracks .The major principle of this method is capillary action,where a low surface tension fluid penetrates into surface discontinuities which are not visible from naked eye. Penetrant may be applied either by brushing or by spraying. Adequate penetration time is allowed and excess of penetrant is then removed and developer is applied which helps to see invisible discontinuities.