Best Practice Corrosion/Erosion Monitoring and Critical Process Indicators Salton Sea KGRA. by Dr. Dan Hoyer, PE Veizades & Associates, Inc.

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1 1 Best Practice Corrosion/Erosion Monitoring and Critical Process Indicators Salton Sea KGRA by Dr. Dan Hoyer, PE Veizades & Associates, Inc.

2 Outline Process Indicators Challenges in High Temperature Corrosion Scaling Resources Materials of Construction Monitoring Degradation of Materials 2

3 Salton Sea Geothermal Fluids Hot (>500 F) High chloride content (>10%) High total dissolved solids (>25%) with high scaling tendency Noncondensible gases (ammonia, carbon dioxide, hydrogen sulfide) Corrosion rates: can exceed 300 mils per year for carbon steel much higher corrosion rates if aerated or acidified brine 3

4 Process Flow Diagram (PFD) 4

5 Material of construction Material Titanium Grade 29 Location Production Wells Expected Service Life Inconel 625 (58% Ni, 23% Cr), Inconel Duplex Stainless Steel (25% Cr, 7% Ni, 4% Mo), 2205 Vessel Piping 2507 Duplex Stainless Steel Injection Wells 316L Stainless Steel Cement Lined Carbon Steel Condensate/NCG Injection line Non-aerated brine tank Price 5

6 Materials of Construction 6

7 Monitoring is essential for safe and sustained operation Degradation Mechanism General corrosion/erosion Pitting or bear claw corrosion Inspection Technique Ultrasonic Thickness Testing (UT) Visual, B scan or C scan UT Stress Corrosion Cracking (SCC) Visual, Dye Pen, Magnetic Particle Inspection, Shear wave UT 7

8 Process Indicators Process Indicator Chemical monitoring: -increase in chloride/silica in steam -decrease of ph in condensate Pressure change vs. time Log book of upset conditions Potential Consequence Higher potential for stress corrosion cracking (SCC) and corrosion Scaling or erosion Target inspection 8

9 Degradation type, knowledge of service and risk of failure drives inspection Major Overhaul Inspection Visual, pictures and thickness measurements at all process changes Additional inspection if there is a potential to crack More Frequent Inspections if: New plant; one year after start-up Poor understanding of degradation mechanism Process parameters outside design Sustained Inspection Baseline prior to start-up Same location for each major overhaul inspection Evaluate corrosion rate (mils per year) changes over life of project 9

10 Corrosion Example of selected inspection locations and frequency Accelerated corrosion of weld zones in alloys 10

11 mixed fluids Turbulence increased turbulence/velocity 11

12 Scale does not adhere to alloys. Easy to remove and clean. John Featherstone- Inventor of Crystallizer/Clarifier and Dr.Dan s Mentor 12

13 Well Casing Pressure Test Video Camera Multiple Finger Caliper 13

14 Massive pitting in HP steam line from wash water impurities Weld failure on steam vessel internals 14

15 UT Inspection Matrix Carbon Steel Evidence of changes in physical and chemical depositional environment 15

16 Summary Physical Chemical ~ Erosion Corrosion Materials of construction can mitigate impacts Monitoring is critical to sustained operation Anticipated degradation process and risk of failure directs frequency and inspection technique 16

17 Discussion

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