XRF Advancements Improve Detection of Trace Silicon in Carbon Steel in On-Line, High-Temperature Process Piping and Components Olympus | Michael W. Hull, Alex Thurston, Dianne Hillhouse ASNT | Long Beach, CA | 27 October 2016
Apr 10, 2017
XRF Advancements Improve Detection of Trace Silicon in Carbon Steel in On-Line, High-Temperature Process Piping and Components
Olympus | Michael W. Hull, Alex Thurston, Dianne Hillhouse ASNT | Long Beach, CA | 27 October 2016
Advances in low-Si testing
Importance of low-Si testing
Challenges of low-Si testing
Importance of low-Si testing
Why positive material identification (PMI)?
“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 “Positive Material Verification: Prevent Errors During Alloy Steel Systems Maintenance” Safety Bulletin, U.S. Chemical Safety and Hazard Investigation Board. Report No. 2005-04-B. October 2006
Why positive material identification (PMI)?
Sulfidic corrosion
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Scale formation Internal diffusion
Factors affecting sulfidic corrosion
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Tem
pera
ture
Source: NCSS Statistical Software, https://www.ncss.com/software/ncss/ncss-plots-and-graphs/
SH
SS
S
SH2CO2H
S
R
CO2H H2
[ ]n [ ]n
[ ]n [ ]n
[ ]n
Alloy effects
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Chromium Silicon
a l l o y I n g c o n t e n t
FeCr2S4
Corrosion Rate vs Silicon Content
0.0
2.0
4.0
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8.0
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18.0
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
Silicon Content (Weight %)
Cor
rosi
on R
ate
(mpy
)
Alloy effects
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Source: American Petroleum Institute Recommended Practice 939-C: Guidelines for Avoiding Sulfidation (Sulfidic) Corrosion Failures in Oil Refineries, 2nd Ed, Annex C
1940 1950 1960 1970 1980 1990 2000 2010 2020
Time • Knowledge • Risk
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1940 1950 1960 1970 1980 1990 2000 2010 2020
Con
stru
ctio
n
Und
erst
andi
ng
History and variation in steel specifications
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C
(max) Si
(min) P
(max) S
(min) Ti
(max) V
(max) Cr
(max) Mn
(max) Fe Ni
(max) Cu
(max) Mo
(max) A53B 0.30* --- 0.05 0.045 --- 0.08 0.4 1.20* bal. 0.4 0.4 0.15 API 5L 0.28* --- 0.08* 0.03 0.06 --- --- 1.85* bal. --- --- --- A105 0.35* 0.1 0.035 0.04 --- 0.08 0.3 1.05* bal. 0.4 0.4 0.12 A106 0.35* 0.1 0.035 0.035 --- 0.08 0.4 1.06* bal. 0.4 0.4 0.15 A181 0.35* 0.1 0.05 0.05 --- --- --- 1.10 bal. --- --- --- A234 0.35* 0.1 0.05 0.058 --- 0.08 0.04 1.06* bal. 0.04 0.04 0.15
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API Recommended Practice 939-C - Guidelines for Avoiding Sulfidic Corrosion Failures in Oil Refineries
§ Result of naturally occurring sulfur compounds found in crude oil.
§ Causes accelerated corrosion in steel fittings, piping, heater tubes, and pressure vessels when the oil is heated for separation.
§ A significant cause of leaks and failures of piping systems within the refining industry.
§ Process streams with hydrogen free, sulfurous material may exhibit corrosion in carbon steel piping with less than 0.1% Si (McConomy Curves)
– Increasing Cr content of the alloy can provide increasing resistance to this form of corrosion
§ Streams with a combination of hydrogen and sulfur-containing materials at elevated temperature can corrode steels with Cr levels below 12% (i.e. non-stainless alloys, Couper-Gorman curves)
– Recommended to use 18Cr-8Ni stainless steel to avoid corrosion
Importance of low-Si testing
Challenges of low-Si testing
Challenges to trace silicon testing
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Challenging
Environmental variables
Contaminations Low concentrations
Surface preparation
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Prepare & verify
Coatings, platings Residual paint Corrosion, scale, oxide layer
Sand-blasting (Residual Si)
Shot-blasting (residual from iron pellets)
Metallic dust
Environmental variables
Source: U.S. Energy Information Administration, U.S. Energy Mapping System, http://www.eia.gov/state/maps.cfm Source: Climate.gov https://www.climate.gov/maps-data/data-snapshots/averagetemp-monthly-cmb-2015-10-00?theme=Temperature
Low concentration
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1
0 20 40 60 80 100
Fluo
resc
ence
Yie
ld
Atomic Number
Fluorescence yield of elements
K Series
L Series
M Series
Mass attenuation coefficient (Fe) Si 2457.94 Cr 110.97 Mn 87.85
Low concentration
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High absorbance
Low emittance
Advances in low-Si testing
Importance of low-Si testing
Challenges of low-Si testing
Vanta™ handheld XRF analyzer engineering
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Temperature control
Vanta analyzer engineering
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Temperature control
Vanta analyzer engineering
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Temperature control
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11:30 AM 12:00 PM 12:30 PM 1:00 PM 1:30 PM 2:00 PM 2:30 PM 3:00 PM 3:30 PM
Instrument Temperature
Spot 1 Spot 2
Vanta analyzer engineering
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Temperature control
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Vanta analyzer engineering Temperature control
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11:30 AM 12:00 PM 12:30 PM 1:00 PM 1:30 PM 2:00 PM 2:30 PM 3:00 PM 3:30 PM
Instrument Temperature
Spot 1 Spot 2
Instrument Stability
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6.390
6.395
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6.405
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6.435
6.440
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6.450
0 100 200 300 400 500 600 700 800 900 1000
Tem
pera
ture
(°C
)
Volta
ge (K
eV)
Stability with Temperature Cycling
Manganese Peak Temperature
Less than 0.002 KeV variance
Instrument Stability
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0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00
10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00
0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000
316 SS Measurement with Temperature Cycling
Cr Mn Ni Mo
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0 10 20 30 40 50 60
Inst
rum
ent T
empe
ratu
re (°
C)
Sequential Test Number
Instrument temperature during hot testing
400 F 500 F 600 F
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Con
cent
ratio
n (%
)
Sequential Test Number
Mn/Mo concentration values during hot testing
Mn 400 F Mo 400 F Mn 500 F Mo 500 F Mn 600 F Mo 600 F
400 °F 500 °F 600 °F
Mn Mo Mn Mo Mn Mo Certified Value 0.86 0.493 0.86 0.493 0.86 0.493 Average (Vanta) 0.88 0.502 0.88 0.504 0.88 0.504 Minimum 0.83 0.486 0.83 0.488 0.83 0.490 Maximum 0.94 0.518 0.92 0.525 0.94 0.527 RSD 6.17% 3.19% 4.95% 3.65% 6.11% 3.72%
Window for high temperature testing
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Before After
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y = 1.0737x - 0.0123 R² = 0.9949
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0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Vant
a M
easu
rem
ent
Certified Assay
Si performance on low alloys
Silicon concentration Alloy grade CS 1117 CS 1144 CS 1050 CS 1018 CS 4140 C ½ Mo
Assay value 0.05 0.18 0.211 0.252 0.28 0.331 Vanta measurement 0.04 0.18 0.219 0.264 0.27 0.348 Standard deviation 0.008 0.012 0.0140 0.0146 0.018 0.0116
Accuracy
Bias
Precision
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0.00
0.03
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0.08
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0.13
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0.18
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0.23
0.25
0.28
0.30
0.33
0.35
0.38
0.40
0 5 10 15 20 25
Con
cent
ratio
n (%
)
Sequential Test Number
Repeatability of Si measurements
CS 1018 CS 4140 CS 1144 CS 1050 C 1/2 Mo
Future Endeavors § Certified samples of lower concentration
§ High temperature calibration for light elements
§ Industrial partners for field testing