What is PMI Testing?

PMI testing, also known as positive material identification, analyzes materials to look at the chemical composition of metals and alloys. It looks at these things during different stages of the alloy manufacturing process. Understanding the exact composition and the grade of alloy enables both the plant workers and the suppliers and the other responsible parties for chain custody of components and to match the alloy specifications. These metals often get selected for their heat resistance, durability and corrosion resistance. 

Why It Matters

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To have the proper alloy in place, it's essential for locations like a petroleum refinery or a chemical plant because the alloy with the right properties often means the difference between safe and efficient testing and lost revenue and time. Each stainless steel grade will differ based on the chemical composition. What's the key difference between the various metal compositions will largely depend on how much Ni, Cr, Fe, Cu or Mo exists. Different grades will each have different properties. To give an example, the 400 series stainless steels have magnetic properties, but the 300 series stainless steels don't. Meanwhile, people also have other grades of metal with similar properties to each other and telling the difference from them can be hard without PMI testing. 

Why Individuals Need PMI Testing in the Refining Industries

PMI testing in the refining industries started as early as around 1992 after OSHA decided to enforce their PSM to avoid injuries and accidents in the work environment. They recognized the need for this guidance because the hazards in the petroleum refineries and chemical processing plants were too great. Because of a real danger with analyzing materials being processed, companies use non-destructive instrumentation. PMI testing will qualify the analysis as non-destructive testing, and it should indicate how the material hasn't been altered and remains in the same condition. The testing ensures there were no signs of structural damage after the analysis.

When To Use PMI Testing

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Look back 200 years ago, and people learn how society only had 12 known metals. Today's world lists 86 known metals and corresponds with the increase in steel and alloy types. Customers ask for PMI testing because they can pick materials for specific applications in an extensive market. After customers receive PMI testing, the company issues a certification for the materials to confirm the authenticity of what they bought. At every stage, PMI testing lets customers design successful business plans for their processes and products. For companies that use alloys, steels and metals for business, PMI testing lets customers make a more educated purchase choice. They can also confidently choose a cost effective approach and know the process decisions.

PMI can also allow for testing for the following circumstances:

• Suspect material

• Part of an assembly too big for shipping

• Can't cut sample for regular testing

• Questions about a sample 

• Misplaced material identification

Some examples of applications where PMI testing improves the performance of a company includes:• 

• X-ray fluorescence analyzer


• Optical emission spectroscopy

• Chemical testing

PMI Testing: Based on Project Specification

The PMI testing procedure adapts to the specifications of the project. For example, customers will modify the procedure differently when they prepare it for an industrial plant construction project because the testing will also look at inspections for both the site and the shop. The procedure examines and prescribes a setup based on the requirements of the PMI. It verifies the piping and vessels of the alloy materials to ensure they consist of an acceptable chemical composition. In addition, PMI testing checks to ensure the correct alloy materials work in the right places. 

Why Do Companies Need PMI Testing?

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Companies require PMI testing because the naked eye can't judge the difference in metals. Most of it looks the same, and a business owner can't spot the difference between 316L and 304 steel from the looks of it. In fact, even the smells will be similar. Testing guarantees the person is right about the materials that enter through their doors. It's important that materials for specific builds are utilizing the proper type of stainless steel. For instance, deciphering the difference between 316L stainless 304 stainless.

The Importance of PMI Testing

PMI testing demonstrates how a business takes the quality of materials seriously, and they will settle for nothing but premium-grade materials from their suppliers. In the long term, satisfied customers mean a future partnership and a growing business.