Monday, December 19, 2011

Why is it important to know what material something is made of

By John Wood


As the specification for materials used in industry becoming more definite, the need for Positive Material Identification PMI verification is more relevant than ever. Upkeep shutdowns are less frequent resulting in equipment requiring longer service life and trustworthiness. As technology develops an ever increasing spread of alloys that are indistinguishable to the eye are being used in individual plants. When upkeep staff replace operational and key components, they have got to be in a position to guarantee that the new part matches all the engineering specs.



Latest commercial incidents have heightened the awareness of the necessity for correct and complete Positive Material Identification PMI inspections



If you are involved in the petroleum and petrochemical refining industries, or Sea, Automotive, Manufacturing, or Aerospace in today's world best practices and Quality Controls the stress is on safety and accident prevention and reliability hasn't ever been larger - increased safety regulations, and more harsh OH&S oversight and fines. Positive material identification (PMI) in alloys and materials used throughout the physical plant and producing processes isn't a choice, but a prerequisite. The random testing of parts and sub-assemblies is now totally unacceptable. Today's best practices require 100% positive material testing of all critical materials.



The compact XRF technique used to pinpoint the chemical composition of the material is valid for the identification of the principal amalgamating elements only. Mostly this provides sufficient data to enable a fairly trusty guess of the material type. This technique can't detect light elements such as carbon and thus the sole analysis should not be used to select materials for applications where the material's strength is imperative. For detailed steel material identification, either a full chemical analysis using OES or ICP should be performed or supplementary mechanical tests should be performed.



The two main Positive Material Identification PMI technologies utilised for alloy identification are X-ray Fluorescence (XRF) and Optical Emission Spectroscopy (OES) LMATS use both where needed.






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