XRF Advancements Improve Detection of Trace Silicon in Carbon Steel in On-line, High Temperature Process Piping and Components

Carbon steels with low-Si (< 0.10 %) content can corrode at an accelerated rate when exposed to sulfidation corrosion conditions. Detecting silicon content in carbon steel via X-ray fluorescence (XRF) and optical emission spectroscopy (OES) has been performed in recent years, though typically during downtime under ambient temperatures. Recent advancements in handheld X-ray Fluorescence (XRF) to quantify levels of silicon (Si) in carbon steel as it pertains to API RP 939-C’s avoiding sulfidation corrosion failures in oil refineries will be discussed. The utility of handheld XRF is explained in practical terms that apply directly to industrial material testing and specifically the surface and environmental variables that affect in situ trace Si testing in high temperatures. Recent developments are identified and their impact as related directly to this application. Dramatically improved hardware and software bring a new level of speed, improved accuracy and precision to the detection of silicon at concentrations below 0.10 wt % in carbon steel process piping systems and components up to 900F. Specifically, better detector/signal processing (1.5X higher count rate, resolution <145 eV) produces improved sensitivity and allows reduced test times in high temperature environments. Additionally the heat sink, standoff and fan design of current instruments mitigate the effects of heat on the instrument.

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