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Corrosion by Process Waters

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Presentation on theme: "Corrosion by Process Waters"— Presentation transcript:

0 Nickel Institute

1 Corrosion by Process Waters
R. W. Ross Consultant Nickel Institute

2 Summary Scaling and Corrosion Effects of Velocity Biological Effects
Chlorides Rouging of SS

3 Water Chemistry Effects
Corrosion Dissolved Oxygen Chlorides pH Hardness Temperature Scale Dissolved Solids Calcium Ions pH Temperature

4 Water Chemistry Effects

5 Corrosion Of Carbon Steel In Water
0.76 72 ºF (22 ºC) 104 ºF (40 ºC) 0.51 Corrosion Rate, mpy Corrosion Rate, mm/y 0.25 pH of Water

6 Corrosion Of Carbon Steel In Low-velocity Water

7 Corrosion Of Carbon Steel Effect Of Velocity In Seawater
1.27 Corrosion Rate, mpy Corrosion Rate, mm/y 0.64 (1.5) (3.0) (4.7) (6.1) (7.6) ft/sec (m/s)

8 Erosion-corrosion - Inlet

9 Erosion-corrosion Flow

10 Erosion-corrosion Tube Blockage

11 High-velocity Seawater >120 fps (36.6 m/s)
Corrosion Rate, Alloy mpy mm/y 625/C <1 < 0.03 400/K <1 < 0.03 718/725/ <1 < 0.03 T-304/T <1 < 0.03 C Steel >300 > 7.62

12 Biological Effects Macrofouling
Mussels Clams Barnacles Plant Life

13 Biological Effects Macrofouling

14 Bacteria Effects - MIC (Microbiologically Induced Corrosion)
Species Oxygen Metals Corrosive Desulfovibrio No Fe, Al, Cu Sulfide Thiobacillus Yes Fe, Cu Sulfuric Acid Gallionella Yes Fe Fe++ to Fe+++ Mn++ to Mn+++

15 Bacteria Effects - MIC Type 304 SS water tank 8 months of service Guam

16 Bacteria Effects - MIC (Type 304 SS, Before Cleaning)

17 Bacteria Effects - MIC (After Cleaning)
0.15 in. (3.8) mm) Max. Attack

18 Bacteria Effects - MIC (After Cleaning - No Attack)

19 Prevention Of MIC Keep The System Clean
Keep Water Flow > 6 fps (2 m/s) Use Bactericide: Chlorine Chlorine Dioxide Hypochlorite Ozone Non-oxidizing

20 Prevention Of MIC Use Continuous Cleaning
Use High Pressure Hydrolancing Use Stainless Steel Scrapers (Hard to Remove or Heavy Deposits) Use Alloy Resistant to MIC

21 Prevention Of MIC - 6% Mo ALLOY

22 Effects of Chlorides

23 Crevice Corrosion Type 303

24 Stainless Steels Localized Corrosion Resistance
Alloy PRE 2507/Alloy 6% Mo Alloys

25 Nickel Alloys Localized Corrosion Resistance
Alloy PRE 6% Mo – 45 22/ C

26 Stainless Steels for Use in Waters
Potable water Type 304 < 200 ppm chlorides Type 316 < 1000 ppm chlorides River water Risk of MIC if water is not treated Use type 316 or higher Mo grades: L Mo Well water Use type 316 or higher Mo grades

27 Do not confuse Chloride Cl- and Chlorine Cl2
Maximum Concentration (ppm) in Water to Avoid Crevice Corrosion Chloride Cl- Chlorine Cl2 304 200 2 316 1000 4 Shock dosing, such as 25 ppm chlorine for 24 hours, is common practice and has not been found to cause problems.

28 Stress Corrosion Cracking (SCC)
Steam Line

29 Chloride SCC Duplex vs T-316 Stainless Steel
No cracking below lines Type 316 (315) 22 Cr Duplex 18 Cr Duplex (204) (93)

30 Effect of Nickel Content on Stress Corrosion Cracking Boiling 45% MgCl2
No SCC Ni Alloys SCC 6% Mo SS Duplex SS


32 How does external environment affect process equipment?
HIGH CHLORIDE WATERS How does external environment affect process equipment?

33 Marine Corrosion of C Steel Relative Corrosion Rates
Marine Corrosion of C Steel Relative Corrosion Rates* – Vary with Sea Conditions Atmospheric Splash Tidal Submerged Subsoil *Protected Harbor 25 mpy (0.64 mm/y) 5 mpy (0.13 mm/y)

34 Uniform Corrosion

35 Effect of Chromium Weight Loss, mg. / sq. dm. 250M Lot 44 Months

36 Alloy C in Marine Atmosphere 56 Years of Exposure


38 Type 304 Fastener In Marine Tide After 6 Months

39 Type 304 Fastener Above Marine Tide After 6 Months

40 Crevice Corrosion

41 Crevice Corrosion of Alloy 825 Heat Exchanger Tubing – Shell Side 85° F, Aerated Seawater

42 Crevice Corrosion of Alloy 625 Waterbox With Deaerated, Treated Seawater

43 Crevice Corrosion of Alloy 825 Heat Exchanger Tubesheet – Water Side 225° F, Deaerated, Treated Seawater Tube to Tubesheet Joint

44 Types Of Severe Crevices
Stationary O Rings Non-Metallic Connector Flange Face Under Gasket Tube to Tubesheet Joint

45 Corrosion of 90-10 Cu-Ni in Seawater
Corrosion Rate, mpy

46 Marine Fouling 18 Months in Quiet Seawater
C Steel Aluminum

47 Fouling of Titanium Waterbox 3 mo. Exposure

48 Fouling of Titanium Waterbox 6 mo. Exposure

49 Effect of Chlorination <1 fps Seawater Flow

50 90-10 Cu-Ni Alloy Fouling - Quiet Seawater
3 Mo 9 Mo 18 Mo 3 Yr 4 Yr 5 Yr

51 90-10 Cu-Ni Intake Piping Desalination Plants

52 Seawater Piping Systems
90-10 Cu-Ni Alloy Seawater Piping Systems

53 Seawater Heat Exchangers
90-10 Cu-Ni Alloy Seawater Heat Exchangers

54 Pumps - Impellers

55 Rouging of Stainless Steels High Purity Water Water For Injection (WFI)

56 Why Use Stainless Steels (316L) for Pharma & Biotech?
Good corrosion resistance and excellent batch to batch cleanability Good structural properties for process equipment Easily formed, fabricated and welded

57 What about Rouging. What is Rouging
What about Rouging? What is Rouging? Rouging is a general term used to describe several species of predominately iron oxide deposits on the wall of piping and vessels in high purity water systems.

58 Rouging is not New! Rouging is not unique to the pharmaceutical and biotech industries. Was recognized over 40 years ago with rouging of SS vessels at Savannah River.

59 Where is Rouge often Found
Water systems, usually high purity water and clean-steam systems Distillation and clean-steam generating equipment Rouge found on wall of vessels, piping and polymer gaskets (Teflon®) downstream of where originated

60 Is Rouge Harmful? No reports or evidence that rouging is precursor to a SS corrosion failure. We are not in a position to comment on whether rouge is harmful to the product being produced. Common practice is to remove rouge.

61 Rouging Generally a loose powdery deposit, but can be tightly adherent
Hydrated or partially hydrated ferric oxide (Fe2O3) or ferroso-ferric oxide (Fe3O4) Usually occurs in high purity ( µS/cm), high temperature water (60 – 100 C)

62 Rouging Reddish brown rust color, but can range from orange to blue-black. Origin is uncertain but generally thought to be ions or colloids that are formed at one location and transported in the solution to another where they are precipitated. Removed by acid cleaning in nitric, phosphoric, citric, or oxalic acid.

63 Rouging - Types Type 1 – Corrosion of Steel, Deposits Downstream Pumps prime suspects – cavitation or erosion when velocity over ~ 100fps and higher temperatures Delta ferrite in cast impellers may contribute by eroding easier and higher iron content Type 2 – Corrosion Product of Stainless Steel Type 3 – Corrosion Product of Stainless Steel in Steam Systems > 100 C

64 Rouging of Stainless Steels

65 Rouging over 4 years inside electropolished Type 316L - column still used to produce ultra-pure water for pharmaceutical use

66 Rouging of Stainless Steels

67 De-rouging & Passivation 3 Steps
Cleaning – detergent wash followed by thorough water rinse De-rouging chemical treatment Passivation followed by thorough water rinse

68 Electrochemical Coloring
Proprietary electrochemical processes – invented in 1972 by Inco, further developed in Japan Interference between the light beams refracted from the substrate and the surface of the oxide film creates color Appearance and color vary with immersion time and surface finish Incident light Color Oxide

69 Experience Music Project

70 Summary Discussed Scaling and Corrosion Described Effects of Velocity
Reviewed Biological Effects Discussed Chlorides Summarized Rouging of SS

71 Questions ?

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