corrosion resistant steels cast irons prepared by robert merryfield
TRANSCRIPT
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
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
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.