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Engineering Database on Galvanic Corrosion in Oil and Gas Production


Abstract:
This report presents quantitative results for galvanic corrosion on stainless steel alloys 4130, 420, 2205, 9Cr and Inconel 718 under four different environments in oil and gas production. The different environments are Sweet Well Production Fluid, Sour Well Production Fluid, Packer Fluid and Acidizing Fluid. Each environment was designed to simulate conditions in which production equipment contacts a corrosive medium.
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Table T1 - 1

Materials for Task 1

Generic Name
C
Mn
S
Ni
Cr
Mo
Others
4130*0.310.46 0.0180.030.88 0.20--
9Cr*0.130.48 0.0100.0578.27 0.96Cu-0.11
420*0.380.36 0.0100.3712.70 0.05Cu-0.10
2205*0.021.83 0.0035.8222.33 2.77N-0.23
718*0.040.13 0.00253.2018.18 3.12Cb+Ta-5.25

Ti-0.95

Beta-C Ti+0.02-- ----5.90 4.10A1-3.4 V-8.2

Zr-3.1


Table T1 - 2

Environments
Four environments were examined. Each was designed to simulate conditions in which production equipment contacts a corrosive medium.
EnvironmentDescription
ASweet Well Production Fluid - Aqueous brine (5 percent NaCl) in equilibrium with 1,200 psia CO2 at 300 F.
BSour Well Production Fluid - Aqueous brine (25 percent NaCl) in equilibrium with 1 psi H2S partial pressure in Task 2 is 400 psi.
CPacker Fluid - Deaerated CaCl2 brine (12 lb/gal), 400 psi CO2 without inhibitor at 350 F.
DAcidizing Fluid - Sequential exposure to concentrated acid (15 percent HCl + inhibitor, 6 days) and spent fluid (0.1 percent HCl, brine, no inhibitor, 7 days). Test temperature is 250 ;F.

Table T1 - 3

Task 1 - Corrosion Coupon Data: Environment A, Control Data
SpecimenArea RatioW (mg)Rate (mpy)Localized Corrosion
S
C
S:C
S
C
S
C
S
C
413041301:1 139.1127.13.6 3.3CR**CR
9 Cr9 Cr1:1 249.9270.07.8 7.1CRCR
4204201:1 759.7572.520.2 15.2----
220522051:1 1.92.10* 0----
7187181:1 2.12.40 0----
TiTi1:12.31.800----

* Less than 0.1 mpy
** CR = Crevice Corrosion
PT = Pitting
S Sample
C Couple
Table T1 - 4

Task 1 - Corrosion Coupon Data: Environment A, Material 4130
SpecimenArea RatioW (mg)Rate (mpy)Localized Corrosion
S
C
S:C
S
C
S
C
S
C
41309Cr1:1 109.1226.62.9 7.1----
41309Cr1:2 176.9351.44.6 4.6----
41309Cr1:4 229.5890.86.0 6.3----
41304201:1 96.6618.22.5 16.4----
41304201:2 108.91086.52.9 14.4----
41304201:4 205.22364.05.4 16.9----
413022051:1 141.72.43.7 0*CR**--
413022051:2 144.74.53.8 0CR--
413022051:4 186.64.94.9 0CR--
41307181:1 166.81.84.4 0*CR,PT--
41307181:2 169.03.94.4 0CR,PT--
41307181:4 198.36.45.2 0CR--
4130Ti1:1 127.12.23.3 0CR--
4130Ti1:2 118.34.93.1 0CR--
4130Ti1:4 148.711.13.9 0CR--
* Less than 0.1 mpy
** CR = Crevice Corrosion
PT = Pitting
S Sample
C Couple
Table T1 - 5

Task 1 - Corrosion Coupon Data: Environment A, Material 9Cr
SpecimenArea RatioW (mg)Rate (mpy)Localized Corrosion
S
C
S:C
S
C
S
C
S
C
9Cr4201:1 422.6492.911.2 13.1CR**--
9Cr4201:2 675.91380.117.9 18.4CR--
9Cr4201:4 794.43029.820.9 21.7CR--
9Cr7181:1 280.42.07.4 0*----
9Cr7181:2 318.33.58.4 0----
9Cr7181:4 413.35.510.9 0----
* Less than 0.1 mpy
** CR = Crevice Corrosion
PT = Pitting
S Sample
C Couple
Table T1 - 6

Task 1 - Corrosion Coupon Data: Environment A
SpecimenArea RatioW (mg)Rate (mpy)Localized Corrosion
S
C
S:C
S
C
S
C
S
C
42022051:1 504.22.913.4 0*PT**--
42022051:2 944.75.025.1 0PT--
42022051:4 950.77.825.3 0PT--
4207181:1 857.91.622.8 0----
4207181:2 1004.93.326.7 0----
4207181:4 1083.65.528.8 0----
* Less than 0.1 mpy
** CR = Crevice Corrosion
PT = Pitting
S Sample
C Couple
Table T1 - 7

Galvanic Corrosion of 4130: Environment A

Area Ratio
Sample/Couple
4:1
2:1
1:1
1:2
1:4
4130/4130

0+

4130/9Cr

(0.6)*1.22.6
4130/420

(0.9)(0.6)2.0
4130/2205

0.2*0.31.4
4130/718

1.01.01.8
4130/Ti

(0.1)(0.3)0.5
* mpy - Indicates that the sample lost weight in excess of that lost when coupled to itself. Numbers
in parenthesis indicate a weight loss that is less than that lost when the sample was coupled to itself.
+ - 4130 Corrosion rate averaged 3.5 mpy when coupled to itself.
Table T1 - 8

Galvanic Corrosion of 9Cr: Environment A

Area Ratio
Sample/Couple
4:1
2:1
1:1
1:2
1:4
9Cr/9Cr

0+

9Cr/4130(1.1)(2.8) (0.4)

9Cr/420

3.7*10.413.6
9Cr/2205




9Cr/718

0.01.003.5
* mpy - Indicates that the sample lost weight in excess of that lost when coupled to itself. Numbers in
;parenthesis indicate a weight loss that is less than that lost when the sample was coupled to itself.
+ - 9Cr Corrosion rate averaged 7.4 mpy when coupled to itself.

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