Article Article
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.

  • “Final Investigation Report: Chevron Richmond Refinery Pipe Rupture and Fire,” U.S. Chemical Safety and Hazard Investigation Board. Report No. 2012-03-I-CA. January 2015.
  • Rebak, Raul B. “Sulfidic corrosion in refineries—a review,” Corrosion Reviews. 2011, 29, 123–133. De Gruyter; doi: 10.1515/CORRREV.2011.021.
  • “Positive Material Verification: Prevent Errors During Alloy Steel Systems Maintenance” U.S. Chemical Safety and Hazard Investigation Board. Safety Bulletin No 2004-04-B. October 2006.
  • Smith, Stephen N., Bruce Brow, and Wei Sun. “Corrosion at Higher H2S Concentrations and Moderate Temperatures” NACE International 2011 Corrosion Conference & Expo.
  • Sun, Jianbo, Chong Sun, Xueqiang Lin, Xiangkun Cheng, and Huifeng Liu. “Effect of Chromium on Corrosion Behavior of P11- Steels in CO2-H2S Environment with High Pressure and High Temperature,” Materials, 2016, 9, 200; doi:10.3390/ma9030200.
  • Kane, R. D. and M. S. Cayard. “A Comprehensive Study on Naphthenic Acid Corrosion” NACE International 2002 Corrosion Conference & Expo.
  • American Petroleum Institute Recommended Practice 571: Damage Mechanisms Affecting Fixed Equipment in the Refining Industry, 2nd Ed., 2011.
  • American Petroleum Institute 570: Piping Inspection Code: In-Service Inspection, Rating, Repair, and Alteration of Piping Systems, 2009.
  • American Petroleum Institute Recommended Practice 578: Material Verification Program for New and Existing Alloy Piping Systems, 2nd Ed., 2010.
  • American Petroleum Institute Recommended Practice 574: Inspection Practices for Piping System Components, 3rd Ed., 2009 11.
Usage Shares
Total Views
142 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage