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Corrosion Resistant Steels Cast Irons

Corrosion Resistant Steels Cast Irons. Prepared by Robert Merryfield. What is Stainless Steel. Any steel with 11% or more chromium. Five General Categories of Stainless Steel Ferritic Martensitic Precipitation-Hardening Austenitic Duplex. Ferritic.

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Corrosion Resistant Steels Cast Irons

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  1. Corrosion Resistant SteelsCast Irons Prepared by Robert Merryfield

  2. What is Stainless Steel Any steel with 11% or more chromium

  3. Five General Categories of Stainless Steel • Ferritic • Martensitic • Precipitation-Hardening • Austenitic • Duplex

  4. Ferritic • Wholly Ferritic Structure-Balance of Chemistry • Wrought Designation-Type 442 • Low Impact Properties • Replaced by 300 Series • Can not be hardened

  5. Martensitic • 12% Chrome Steels (No nickel) • 400 Series • Wrought-410, 416, 440 • Cast CA-15, CA-120, CA6-NM • Tough w/Hardness to500 HB • Applications • Pump Components [Shafts and Sleeves] • Hydraulic Cylinders • Wear Rings • Used in API Pumps not CPI

  6. Austenitic 300 Series • Most Prevalent in the CPI • Nickel >8%-Structure Austenitic • 18-8 SS (304) original • 316- Cast-CF8M [18% Cr-9%Ni-2.5%Mo] • 316-Greater Pitting Resistance • Alloy 20- Cast CN7M [18% Cr-30% Ni-2% Mo]

  7. Austenitic Superalloys • Nickel Based • Nickel-Chromium-Molybdenum Alloys • Hastelloy C-276 [Cast CW-12MW] • Hastelloy C-22 [Cast CX-2MW ] • Inconel 625 [Cast CW-6MC] • Nickel-Molybdenum Alloys • Hastelloy B [Cast N7M]

  8. Duplex Stainless Steels • Metallurgical Structure 50% Ferrite-50%Austenite • High Strength with Good Ductility • Excellent Resistance to SCC in Sea Water • Good Abrasion Resistance • Used in Fertilizer Plants • Grades • Ferallium 255 [Cast CD4MCU] • 2205

  9. Additional Corrosion Resistant Alloys • Nickel • Used for Severe Caustic Environments • Nickel-Copper [Monel] [Cast M-35] • Excellent in Sea Water Applications • Zirconium & Titanium • Excellent When SCC is Problem for Other SS

  10. Cast Irons • Unalloyed Gray and Ductile • Corrosion resistance equal to or better than steel • Excellent dampening affect • Poor ductility but high compressive strength • low cost • High Nickel Austenitic Cast Iron (NiResist) • 18% or more Nickel content • Resist to Conc. Sulphuric Phosphoric & Sea water

  11. Labour proprietary materials • R-55 55% Nickel material designed for H2SO4 at higher temperatures • A-48 Duplex material, similar to CD4MCu • Elcomet K similar to Alloy 20 • Y-17 similar to Hastelloy C • Y-30 similar to Hastelloy B

  12. So, all I need is the Ph value to select a suitable material? No……the 1-14 Ph range only tells us part of the story.

  13. What info do you need? • Concentration of all the chemicals • Normal and maximum temperatures • Presence of solids • Life expectancy of the material

  14. Corrosion Resistant Chart Sulfuric Acid

  15. Most common chemicals • H2SO4 - Sulfuric Acid • HCl - Hydrochloric Acid • NaOH - Sodium Hydroxide (Caustic) • H2O2 - Hydrogen Peroxide • H2O - Water

  16. H2SO4 (Sulfuric Acid) • Properties : Clear, odorless, oily. s.g. up to 1.84 • Hazards : Strong irritant to tissue. Reacts violently with water. • Global Production: 165 million t/yr • Distribution : Trains, Trucks, Barges • Uses : Fertilizers, Paints, Explosives, Batteries, P&P, Specialty Chemicals, WTP

  17. H2SO4 cont’d • Materials : See chart • Pump types : ANSI, Taber, Self Priming • Seals : Carbon/Ceramic (>90%) T.C. or special Carbon Viton elastomers (Teflon above 125o F) DO NOT FLUSH WITH WATER

  18. H2O2 (Hydrogen Peroxide) • Properties : Stable; s.g 1.2 • Hazards : Fire; Explosive;Toxic and strongly irritating. Releases Oxygen when transferred • Distribution : Trains, Trucks • Uses : Bleaching textiles, Wood Pulp; Hair; Rocket Fuel; Water Treatment; P&P • Pump Mat’l : 316SS or Aluminum

  19. H2O2 cont’d • Pump types: Self Primers or TFA • Mech. Seals: SiC/SiC or GFT/Ceramic Viton or Teflon • Major customers: FMC; Dupont; Elf Autochem Tank Car Manufacturers • Specials: Pump to be pickled to ensure clean inside.

  20. Sodium Hydroxide (NaOH) • Properties : White. s.g 1.55 max. < 80cP viscosity • Hazards : strong irritant. Corrosive to tissue • Distribution : Trains, Trucks, Barges • Uses : Chemical manufacture; P&P; detergents; electro plating; food additive; bleaching; dyeing • Pump types : ANSI; Self Primer; Taber

  21. Sodium Hydroxide cont’d • Pump materials: 50% <125F- Iron, Steel >125F- 316SS 73% or >170F - Nickel • Mechanical seals: Carbon/T.C. (no SiC) EPR (no Viton)

  22. Hydrochloric Acid (HCl) • Properties : Colorless -slightly yellow, fuming. Concentration <38% s.g. 1.19 • Hazards : Toxic, strong irritant to tissue. • Uses : Pickling, scale removing, food processing, pharmaceuticals • Pump types : ANSI; Self Pimer; Taber

  23. Hydrochloric Acid cont’d • Pump materials: Hast. B/C, FRP <30% • Mechanical seals: Carbon/Ceramic Viton

  24. Water (H2O) • Hazards: drowning or shortage. • Properties: Steep Pv curve (limiting us to 350o F max.) • Specials : High temp. water has no lubricity. • Pump mat’l: D.I. or SS • Mech. Seal: Carbon/Ceramic (cold water)see supplement for Hot water.

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