ApI 578 deals with Positive Material Identification (PMI) testing of metal to determine metal chemistry while ensuring the metal specified for the project is the correct grade. There are two options for complying with API 578; one is using handheld XRF units and the second is mobile OES (in this case the Compact Port is the mobile OES instrument of choice).
Handheld XRF for API 578
Handheld XRF is an excellent tool for analyzing pipes, flanges, welds and other materials in the field. Operators of the instrument need little to no training and the surface to be tested requires limited preparations before testing. However, there are a few drawbacks to using handheld XRF.
- Operators don’t get to see the entire chemistry of the test material (no carbon values are provide and silicon analysis is weak)
- Unable to distinguish certain grades (can not tell the difference between 316 & 316L, 4140 & 4150 or 1010 & 1020
- Unable to accurately analyze material at temperatures over 120F
Mobile OES for API 578
Mobile OES has a distinct advantage when it comes to PMI for both qualitatively and quantitatively analysis. The Compact Port in particular is built with a laboratory grade optical system which produces low levels of detection while maintaining repeatability between tests.
Advantages of Mobile OES for API 578
- The Compact Port produces a full chemical analysis in spark mode for multiple metal bases (Fe, Al, Cu, SS, Ti) including Carbon, Phosphorous, Sulfur, Boron and Nitrogen in Duplex Stainless Steel
- Easily analyze weld deposits, tubing, flanges and fasteners
- Analyze for elevated Silicon levels at temperatures up to 750F
- Store Carbon Equivalent formula’s in the instrument and report the results as a pseudo element
The Drawbacks of Mobile OES
- Special care must be taken to transport the instrument. A highly refined optical system is susceptible to vibrations causing a shift in analysis results. Even a shift of 1 nanometer will skew results
- The sample surface must be prepared before analysis with an aluminum oxide grinding wheel. There’s no way around laboratory quality results with sample preparations
- Argon is used to purge the probe face. The argon purge allows for low levels of detection but provides unparalleled accuracy and repeatability
- Operators will need to acquire a hot work permit if testing occurs during tubing operation
Conclusion of API 578 and Metal Testing Tools
Mobile OES and handheld XRF both have strengths and weaknesses when it comes to API 578 and PMI. However, Mobile OES has the distinct advantage of providing a complete breakdown of chemical composition and can be used for API 939C or CE analysis.
Don’t be fooled into thinking that Handheld XRF is accurate enough to take a gamble on carbon or silicon levels as a remainder of analysis results. Integrity managers should not be guessing about elemental content when they should know the entire picture.
For more information on the Compact Port and API 578 contact us today!