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DISEÑO DE EQUIPOS E INSTALACIONES

Seleción de materiales y prevención de la corrosión Tablas.1

Acid solutions

Neutral solutions

Static or slow

movingTurbulent

Static or slow

movingTurbulent

Cast iron, flake graphite, plain or low-alloy 1 3 4 5 0 4 0 4 3 4 2

Ductile iron (higher strength and hardness may be attained by composition and heat treatment or both)

1 3 4 5 0 4 0 4 4 4 3

Ni-Resist corrosion-resistant cast irons 4 5 5 5 0 5 0 5 5 5 5

Durion-14% silicon iron 6 6 2 5 6 6 3 5 5 5 5

Mild steel, also low-alloy irons and steels 1 3 4 5 0 4 0 4 3 4 2

Stainless steel, ferritic 17%, Cr type 2 4 4 6 5 6 0 4 6 1 4

Stainless steel, austenitic 18 Cr; 8 Ni type 3 4 5 6 6 6 0 6 6 2 5

Stainless steel, austenitic 18 Cr; 12 Ni; 2.5 Mo type 4 5 5 6 5 6 1 6 6 3 5

Stainless steel, austenitic 20 Cr; 29 Ni; 2.5 Mo; 3.5 Cu type 5 6 5 6 5 6 2 2 6 4 6Incoloy 825 nickel-iron-chromium alloy (40 Ni; 21 Cr; 3 Mo; 1.5 Cu; balance Fe)

6 6 5 6 5 6 2 6 6 4 6

Hastelloy alloy C-276 (55 Ni; 17 Mo; 16 Cr;6 Fe; 4 W) 5 6 5 6 4 6 5 6 6 6 6

Hastelloy alloy B-2 (61 Ni; 28 Mo; 6 Fe) 6 5 4 4 0 3 0 6 6 4 4

Inconel 600 (78 Ni; 15 Cr; 7 Fe) 3 6 6 6 3 6 1 6 6 4 6

Copper-nickel alloys up to 30% nickel 4 5 5 0 0 4 1 6 6 6 6

Monel 400 nickel-copper alloy (66 Ni; 30 Cu; 2 Fe) 5 6 6 1 0 5 1 6 6 4 6

Nickel 200 commercial (99.4 Ni) 4 5 6 1 0 5 0 6 6 3 5

Copper and silicon bronze 4 4 4 0 0 4 0 6 5 4 1

Aluminum brass (76 Cu; 22 Zn; 2 Al) 3 4 2 0 0 3 0 6 6 4 5Nickel-aluminum bronze (80 Cu; 10 Al; 5 Ni; 5 Fe) 4 4 2 0 0 3 0 6 6 4 5Bronze, type A (88 Cu; 5 Sn; 5 Ni; 2 Zn) 4 5 4 0 0 4 0 6 6 5 5

Aluminum and its alloys 1 3 0 6 0-5 0-4 0 4 5 0-5 4

Lead, chemical or antimonial 5 5 2 2 0 2 0 6 5 5 3

Silver 4 6 6 0 0 2 0 6 6 5 5

Titanium 3 6 2 6 6 6 6 6 6 6 6Zirconium 3 6 2 6 6 6 2 6 6 6 6

Pitting media^,

acid ferric chloride solutions

TABLE 28-2 General Corrosion Properties of Some Metals and Alloys* Nonoxidizing or reducing media Liquids

Freshwater supplies Seawater

Natural waters

6: Normally excellent.

excluding hydrochloric

e.g., phosphoric,

sulfuric, most

conditions, many

many nonoxidizin

g salt solutions, chlorides, sulfates

Caustic and mild

alkalies, excluding

ammonium hydroxide

Amonium hydroxide

and amines

Acid solutions e.g. nitric

Neutral or alkaline

solutions e.g.

persulfates, peroxides, chromates

5: Good to excellent.

Materials

Ratings: 0: Unsuitable. Not available in form required or not suitable for fabrication requirements or not suitable for corrosion conditions.1: Poor to fair.2: Fair. For mild conditions or when periodic replacement is possible. Restricted use.3: Fair to good.4: Good. Suitable when superior alternatives are uneconomic.

Alakine solutions Oxidizing media

Moist condensate

Dry at high temperature, promoting

slight dissociation

Reducing e.g., heat-treatment furnace gases

Oxidizing, e.g., flue

gases

Ambient air, city or

industrial

Moist, e.g., chlorine

below dew point

Dry, e.g., fluorine

above dew point

Cast iron, flake graphite, plain or low-alloy 4 4 1 1 3 0 2 0 2<400

1<750Ductile iron (higher strength and hardness may be attained by composition and heat treatment or both)

4 4 1 1 3 0 2 0 2<4001<750

Ni-Resist corrosion-resistant cast irons 5 5 3 2 4 0 2 3 3<400

2>750Durion-14% silicon iron 6 4 4 3 6 0 0 4 1<400

Mild steel, also low-alloy irons and steels 4 4 1 1 3 0 3 0 3<400

1<750

Stainless steel, ferritic 17%, Cr type 5 6 3 2 4 0 2 0 2<400

Stainless steel, austenitic 18 Cr; 8 Ni type 6 6 2 3 5 0 2 0 3<400

Stainless steel, austenitic 18 Cr; 12 Ni; 2.5 Mo type 6 6 2 4 6 0 3 2 4<400

Stainless steel, austenitic 20 Cr; 29 Ni; 2.5 Mo; 3.5 Cu type 6 6 2 4 6 1 3 3 4<400Incoloy 825 nickel-iron-chromium alloy (40 Ni; 21 Cr; 3 Mo; 1.5 Cu; balance Fe)

6 6 2 5 6 2 3 3 4<4003<750

Hastelloy alloy C-276 (55 Ni; 17 Mo; 16 Cr;6 Fe; 4 W) 6 6 3 4 6 5 4 4 4<750

Hastelloy alloy B-2 (61 Ni; 28 Mo; 6 Fe) 6 5 3 2 5 1 3 5 4<750

3<900

Inconel 600 (78 Ni; 15 Cr; 7 Fe) 6 6 2 4 6 2 5 3 5<4004<900

Copper-nickel alloys up to 30% nickel 6 5 2 2 5 1 5 2 4<4003<750

Monel 400 nickel-copper alloy (66 Ni; 30 Cu; 2 Fe) 6 6 2 3 5 2 6 3 6<400

3<750

Nickel 200 commercial (99.4 Ni) 6 6 2 2 4 2 6 2 6<400

Copper and silicon bronze 6 5 2 2 5 0 5 2 3<400

Aluminum brass (76 Cu; 22 Zn; 2 Al) 6 5 2 2 5 0 4 2 2<400Nickel-aluminum bronze (80 Cu; 10 Al; 5 Ni; 5 Fe) 6 5 2 3 5 0 4 3 3<400Bronze, type A (88 Cu; 5 Sn; 5 Ni; 2 Zn) 6 5 2 2 5 0 4 3 3<400

Aluminum and its alloys 5 2 5 4 5 0 6 0 3<400

Lead, chemical or antimonial 2 0 4 3 5 0 1 3 0

Silver 6 5 4 4 4 5 5 3 4<400

Titanium 6 5 3 5 6 6 0 1 0Zirconium 6 6 3 5 6 6 1 6 0

Halide acids,

moist, e.g., hydrochloric hydrolysis products of

organic halides

Hydrogen halides, dry,

e.g., dry hydrogen

chloride, ºF

Steam Furnace gases with Halogens

Common Industrial media Halogens and derivatives

TABLE 28-2 General Corrosion Properties of Some Metals and Alloys*

Materials

Gases

Cast iron, flake graphite, plain or low-alloy Cast No Fair¤ 45 6.7

Ductile iron (higher strength and hardness may be attained by composition and heat treatment or both)

Cast No Good¤ 67 7.5

Ni-Resist corrosion-resistant cast irons Cast No Good¤ 22-31 10.3

Durion-14% silicon iron Cast No No 22 7.4 Very brittle, susceptible to cracking by mechanical and thermal shock

Mild steel, also low-alloy irons and steels Wrought, cast Good Good 67 6.7

High strengths obtainable by alloying, also improved atmospheric corrosion resistence. See ASTM specifications for particular grade

Stainless steel, ferritic 17%, Cr type Wrought, cast, clad Good Good¤ 78 6.0 AISI type 430

ASTM corrosion- and heat-resisting steels

Stainless steel, austenitic 18 Cr; 8 Ni type

Wrought, cast, clad Good Good 90 9.6

AISI type 304ASTM corrosion- and heat-resisting steels; stabilized or LC types used for welding

Stainless steel, austenitic 18 Cr; 12 Ni; 2.5 Mo type


AISI type 316ASTM corrosion- and heat-resisting steel; LC type used for welding

Stainless steel, austenitic 20 Cr; 29 Ni; 2.5 Mo; 3.5 Cu type Wrought, cast Good Good 90 9.4 ACI CH-7M; good resistance to sulfuric, phosphoric, and fatty

acids at elevated temperaturesIncoloy 825 nickel-iron-chromium alloy (40 Ni; 21 Cr; 3 Mo; 1.5 Cu; balance Fe)

Wrought, cast, clad Good Good 100 7.3 Special alloy with good resistance to sulfuric, phosphoric, and

fatty acids; resistant to chlorides in some environments

Hastelloy alloy C-276 (55 Ni; 17 Mo; 16 Cr;6 Fe; 4 W)

Wrought, cast, clad Fair Good 145 6.3 Excellent resistance to wet chlorine gas and sodium

hypochlorite solutionsHastelloy alloy B-2 (61 Ni; 28 Mo; 6 Fe)

Wrought, cast, clad Fair Good 135 5.6 Resistant to solutions of hydrochloric and sulfuric acids

Inconel 600 (78 Ni; 15 Cr; 7 Fe) Wrought, cast, clad Good Good 90 8.9 Wide application in food and pharmaceutical industries

Copper-nickel alloys up to 30% nickel Wrought, cast, clad Good Good 38-62 9.3-8.5 High-iron types excellent for resisting high-velocity effects in

condenser tubes

Monel 400 nickel-copper alloy (66 Ni; 30 Cu; 2 Fe)


Widely used for sulfuric acid pickling equipment; also for propeller shafts in motor boats; precautions needed to avoid sulfur attack during fabrication

Nickel 200 commercial (99.4 Ni) Wrought, cast, clad Good Good 54 6.6 Widely used for hot concentrated caustic solutions;

precautions needed to avoid sulfur attack during fabrication

Copper and silicon bronze Wrought, cast, clad Excellent Fair 29 9.3-9.5 Unsuitable for hot concentrated mineral acids or for high-

velocity HF

Aluminum brass (76 Cu; 22 Zn; 2 Al) Wrought, cast Good Fair 60 10.3 Possibility of developing localized corrosion in seawater

Nickel-aluminum bronze (80 Cu; 10 Al; 5 Ni; 5 Fe) Wrought, cast Good Fair 60-80 9.4 Ship propellers an excellent application

Bronze, type A (88 Cu; 5 Sn; 5 Ni; 2 Zn) Cast No ¤ 45 11.0 High strengths obtained by heat treatment; not susceptible to

Aluminum and its alloys Wrought, cast, clad Good Good 9-90 11.5-13.7

Extent of corrosion dependent upon type and concentration of acidic ions; wide range of mechanical properties obtainable by acidic ions; wide range of mechanical properties obtainable by alloying and heat treatment

Lead, chemical or antimonial Wrought, cast, clad Excellent Good 2 16.4-15.1 High purity "chemical lead" preferred for most applications

Silver Wrought, cast, clad Excellent Good 21 10.6 Used as a lining

Titanium Wrought, cast Fair Good¤ 6-90 5.0 Possibility of red fuming HNO3 initiating explosions; good resistance to solutions containing chlorides

Zirconium Wrought, cast Fair Good¤

Remarks

TABLE 28-2 General Corrosion Properties of Some Metals and Alloys*

Materials Available forms

Cold formability in wrought and clad

form

Weldability

Maximum strength annealed

condition * 1000lb./in.in

.

Coefficient of thernal

expansion, millionths per F, 70-

212 F

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