New Practice for Performing Positive Material Identification (PMI)
1. Scope
1.1.This practice defines a fast screening framework for alloy verification of stainless-steel products. Testing can occur after all fabrications (Final) or throughout the manufacture process. 1.2.Positive material identification can be thought of as a current and fast form of product or check analysis where a partial chemical composition is developed for the exclusive use of verifying material grade. This technique has limitations and is not error proof. Its advantage is more verifications are possible than a single check analysis. 1.3.Portable spectrographic, normally handheld X-ray fluorescence (XRF) or optical equipment is used for fast verification. The aim is to exclude from outside of similar alloys defined in 1.4.Allowances are made for equipment limitations within this technique. When using portable XRF, elements with atomic numbers of 22 or below (for example, Titanium, aluminum, carbon, silicon, sulfur, and phosphorus) show poor response. This equipment because of its limitations shall not be used for chemical composition analysis (quantitative) nor will it prove a specific sample conforming to a material specification (chemistry limits). 1.5.This PMI practice is intended as a verification within families of similar alloys, or alternatively it excludes possibilities of dissimilar alloy families. 1.6.This standard does not purport to address all the safety concerns...
Keywords
Check analysis, PMI, spectrographic, chemistry:
Rationale
Check analysis, has become dated with the advent of portable spectrographic. So much so that most people are confused by check analysis and how it differs from melt. It is my hope that after a std practice exists product specs can make a check analysis optional as in PMI or Check at the option of the producer.
