Corrosion Resistant Steels Cast Irons Prepared by Robert Merryfield

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

l Five General Categories of Stainless Steel »Ferritic »Martensitic »Precipitation-Hardening »Austenitic »Duplex

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

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

Precipitation-Hardening l Chrome-Nickel Steel l Martensitic Structure l Contains Copper-Precipitates l Designation »17-4PH and 15-5PH [Wrought] »CB7Cu [Cast] »High Strength –80,00 psi Tensile Solution Condition –120,000 psi Aged Condition »Corrosion Resistance-Between 300 & 400 SS

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

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

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

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

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

Cast Irons (Cont.) l High Chromium Cast Iron »Alloyed with 12% to 30% Cr »Resistant to Oxidizing Acids, i.e. Nitric Acid »Also saline solutions, organic acids and marine environments »Extremely Abrasion Resistant

Copper Alloys l Copper Alloys used in many environments because: »Corrosion Resistance »Good Electrical and Thermal Conductivity »Ease of fabrication and welding »Resistance to biofouling

Brasses l Brass is an alloy of Copper and Zinc l Excellent corrosion resistance to aqueous solutions l Corrosion resistance decreases with Zinc content greater than 15%. l Susceptible to dealloying or dezincification

Bronzes l Bronzes are Copper and Tin l Addition of Tin and Phosphorus to copper produces good resistance to flowing seawater l Aluminum Bronze »Excellent resistance to impingement corrosion »Al provides increased corrosion resistance »Resistant to Phosphoric, Sulfuric, NaCl »Especially resistant to brackish water

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

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.

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

Corrosion Resistant Chart Sulfuric Acid

Most common chemicals l H 2 SO 4 - Sulfuric Acid l HCl - Hydrochloric Acid l NaOH - Sodium Hydroxide (Caustic) l H 2 O 2 - Hydrogen Peroxide l H 2 O - Water

H 2 SO 4 (Sulfuric Acid) l Properties: Clear, odorless, oily. s.g. up to 1.84 l Hazards: Strong irritant to tissue. Reacts violently with water. l Global Production: 165 million t/yr l Distribution: Trains, Trucks, Barges l Uses: Fertilizers, Paints, Explosives, Batteries, P&P, Specialty Chemicals, WTP

H 2 SO 4 contd l Materials: See chart l Pump types: ANSI, Taber, Self Priming l Seals: Carbon/Ceramic (>90%) T.C. or special Carbon Viton elastomers (Teflon above 125 o F) DO NOT FLUSH WITH WATER

H 2 O 2 (Hydrogen Peroxide) l Properties: Stable; s.g 1.2 l Hazards: Fire; Explosive;Toxic and strongly irritating. Releases Oxygen when transferred l Distribution: Trains, Trucks l Uses: Bleaching textiles, Wood Pulp; Hair; Rocket Fuel; Water Treatment; P&P l Pump Matl: 316SS or Aluminum

H 2 O 2 contd l Pump types:Self Primers or TFA l Mech. Seals:SiC/SiC or GFT/Ceramic Viton or Teflon l Major customers: FMC; Dupont; Elf Autochem Tank Car Manufacturers l Specials:Pump to be pickled to ensure clean inside.

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

Sodium Hydroxide contd l Pump materials: 50% 125F- 316SS 73% or >170F - Nickel l Mechanical seals:Carbon/T.C. (no SiC) EPR (no Viton)

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

Hydrochloric Acid contd l Pump materials:Hast. B/C, FRP <30% l Mechanical seals:Carbon/Ceramic Viton

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