Positive Material Identification 

PMIPositive Material Identification is a specialised non-destructive testing method for identifying the composition of components and material. The mechanical integrity of safety critical plant is dependent on the correct materials being used for vessels, piping, valves and pumps. If the incorrect material is used, the design assumptions are invalid and the components may fail due to the material having lower strength or poor corrosion resistance.

PMI provides information of the grade of metal and on the alloy composition. PMI is applied to new components on receipt from the manufacturer to ensure they meet specification. PMI provides material composition of existing, installed components to inform decisions on change of use or operating parameters.  If it is not known what material has been used for a component or a material certificate is missing then PMI provides the solution for asset management purposes. PMI can also be use to sort scrap material and support re-use and recycling.

PMI can also identify contaminants or hazardous products in filters, slurries and paint to aid health and safety and environmental management.

A common PMI technique is X-ray fluorescence (see next month's What the Hec?!). PMI has found widespread use in the chemical and petrochemical industries. API (see link to the left) has produced a recommended practice, API 578, on guidelines for material control and material verification programmes and PMI certification against this RP is available.

For more information on PMI:
Put Positive Material Identification into a search engine (note: don't just put in PMI or you will get the Project Management Institute or Pensions Management Institute or anything but Positive Material Identification!)
or see:

What the hec?! articles are not intended to be the definitive account on the topic or acronym in question. Readers’ comments and contributions are welcomed. Email: