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Corrosion Resistant Steels Cast Irons Prepared by Robert Merryfield.
Transcript of Corrosion Resistant Steels Cast Irons Prepared by Robert Merryfield.
Corrosion Resistant SteelsCast 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
» 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
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]
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]
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
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
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
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
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?
Concentration of all the chemicals Normal and maximum temperatures Presence of solids Life expectancy of the material
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0 10 20 30 40 50 60 70 80 90 100
% CONCENTRATION - H 2SO4
316SS (to 10%)Elcomet KR55Y30
316SS (to 75oF, 25%)
Elcomet K (to 150oF)
Allow 48 (to 75oF, 25%)
SteelElcomet KY-30TantalumAllow 48 (above 80%)
Y-30R55MonelTantalum
Elcomet K (to 150 oF)
Y-30Tantalum
(to 374oF)
Y-30R55Tantalum
Elcomet K (to 150 oF)
R55 (to 250oF)Tantalum
(to 374oF)
Corrosion Resistant Chart Sulfuric Acid
Most common chemicals
H2SO4 - Sulfuric Acid HCl - Hydrochloric Acid NaOH - Sodium Hydroxide (Caustic) H2O2 - Hydrogen Peroxide
H2O - Water
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
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
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
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.
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
Sodium Hydroxide cont’d
Pump materials:50% <125F- Iron, Steel
>125F- 316SS73% or >170F - Nickel
Mechanical seals: Carbon/T.C. (no SiC)
EPR (no Viton)
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
Hydrochloric Acid cont’d
Pump materials: Hast. B/C, FRP <30%
Mechanical seals: Carbon/CeramicViton
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.