SciAps Can Meet Refinery Residual Requirements in Steel

February 28, 2020

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The SciAps Z LIBS (laser) is the only handheld analyzer that can measure every element and meet all of the residual requirements for HF alkylation units in refineries. The SciAps Z is a handheld carbon analyzer capable of measuring the carbon content in carbon steels and alloy steels. Not only can the Z determine the carbon content, it can measure and sum Cr, Ni, and Cu with the following conditions:

  • If C > 0.18%, then RES =  Ni + Cu, and RES < 0.15%
  • If C <= 0.18%, then RES = Cr + Ni + Cu, and RES < 0.15%.

It can also determine the additional elements and constraints:

  • Nb < 0.02
  • V < 0.02
  • Nb + V < 0.03%
  • CE (carbon equivalents) < 0.43

Historically, operators have used handheld X-ray guns to perform positive material identification for HF alkylation units. While handheld X-ray cannot measure carbon content, it has been preferred because it is much easier to use and far more portable than the carbon-capable spark OES technology.

What's changed is that now handheld LIBS technology puts the power of spark OES into a handheld. The Z offers the added benefit of measuring carbon in addition to other metals including Cr, Ni, Cu for API 751 residual elements. In some cases, if C > 0.18%, then CR can be dropped from the residuals, and the more relaxed RE requirement of Ni% + Cu% < 0.15% may be utilized.

The Z’s Residuals App automatically chooses the correct formula depending on carbon concentration, or the user may force a specific formula.

It should be noted that really low restrictive specifications for elements like Nb remain challenging for LIBS because Nb, like Mo, Ta, and W, is a refractory element, and the laser doesn’t vaporize it as efficiently as it does Cr, V, Cu, Mg, etc. For those who need a more efficient analysis of Nb at really low concentrations, X-ray is the best option. The SciAps X-550 is an XRF instrument with the lowest LODs (limits of detection) offered in the industry. Offering limits of detection for Nb at 10 ppm (0.001%) and V at 20 PPM (0.002%), the X-550 easily measures the following requirements:

  • Nb < 0.02
  • V < 0.02
  • Nb + V < 0.03%

The other fact to consider in working with low residual steels is that much of the steel product comes from recycled steel. The more recycled steel is used, the higher the levels of Cr, Ni, Cu and other elements. Getting steel that meets residual requirements is harder and harder, which means more testing must be done. For this reason, a practical option for efficiently meeting residual requirements for HF alkylation units in refineries is the SciAps One Box, featuring the LIBS for C and CE and the XRF for those low restrictive element specifications like Nb. Using these 2 complementary technologies (Z and X) is a perfect solution for meeting your Low RE needs.

SciAps, Inc. is a leading manufacturer of handheld XRF and LIBS analyzers for every industry. Their newest family of XRF analyzers, the X-550 and X-505, are the smallest, lightest weight and fastest XRF analyzers ever made. Learn more at The NACE paper "03651 Specification for Carbon Steel Materials for Hydrofluoric Acid Alkylation Units" originated test and corrosion rate measurement procedures for evaluating materials in HF environments and a carbon steel materials specification with respect to the levels of residual elements and carbon in steels for HF alkylation equipment.

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