1 Sulfur Dioxide Author: L. Hasenberg/Editor: R. Bender Page Page Survey Table 2 A 35 Platinum metals (Ir, Os, Pd, Ru) 240 and their alloys Introduction 5 A 36 Tin and tin alloys 242 A Metallic materials 37 A 37 Tantalum, niobium and their 243 A 1 Silver and silver alloys 37 alloys A 38 Titanium and titanium alloys 243 A 2 Aluminium 42 A 39 Zinc, cadmium and their alloys 246 A 3 Aluminium alloys 48 A 40 Zirconium and zirconium alloys 251 A 4 Gold and gold alloys 55 A 41 Other metals and alloys 252 A 5 Cobalt and cobalt alloys 57 A 6 Chromium and chromium 72 alloys B Non-metallic inorganic materials 254 A 7 Copper 74 B 1 Asbestos 254 A 8 Copper-aluminium alloys 83 B 2 Natural stones 254 A 9 Copper-nickel alloys 85 B 3 Carbon and graphite 255 A 10 Copper-tin alloys (bronzes) 85 B 4 Binders for building materials 256 A 11 Copper-tin-zinc alloys (red brass) 87 (e.g. mortar and concrete) A 12 Copper-zinc alloys (brass) 87 B 5 Acid-resistant building materials 257 A 13 Other copper alloys 90 and binders (putties) A 14 Unalloyed steels and cast steel 90 B 6 Glass 258 A 15 Unalloyed cast iron 122 B 7 Quartz ware and quartz glass 258 A 16 High-alloy cast iron, high-silicon 124 B 8 Enamel 259 cast iron B 9 Porcelain 260 A 17 Structural steels with up to 12 % 124 B 10 Stoneware 261 chromium B 11 Refractory materials 261 A 18 Ferritic chromium steels with 130 B 12 Oxide ceramic materials 261 more than 12 % chromium B 13 Metallo-ceramic materials 261 A 19 Ferritic-austenitic steels with 130 (carbides, nitrides) more than 12 % chromium B 14 Other inorganic materials 262 A 20 Austenitic chromium-nickel 145 steels A 21 Austenitic chromium-nickel- 165 C Organic materials 264 molybdenum steels C 1 Natural fibers (wool, cotton, silk 264 A 22 Austenitic chromium-nickel 196 etc.) steels with special alloying C 2 Bituminous compositions 264 additions (bitumen, asphalt, pitch) A 23 Special iron-based alloys 202 C 3 Fats, oils, waxes 265 A 24 Magnesium and magnesium 205 C 4 Wood 265 alloys C 5 Modified cellulosics 266 A 25 Molybdenum and molybdenum 205 C 6 Furan resins 267 alloys C 7 Polyolefins and their copolymers 267 A 26 Nickel 206 C 8 Polyvinyl chloride and its 269 A 27 Nickel-chromium alloys 214 copolymers A 28 Nickel-chromium-iron alloys 216 C 9 Polyvinyl esters and their 271 A 29 Nickel-chromium-molybdenum 218 copolymers alloys C 10 Phenolic resins 275 A 30 Nickel-copper alloys 223 C 11 Acrylic resins 275 A 31 Nickel-molybdenum alloys 227 C 12 Polyamides 276 A 32 Other nickel alloys 228 C 13 Polyacetals 277 A 33 Lead and lead alloys 237 C 14 Polyesters 277 A 34 Platinum and platinum alloys 239 C 15 Polycarbonates 281 Corrosion Handbook: Sulfate Dioxide, Sodium Sulfate Edited by: G. Kreysa, M. Schütze Copyright © 2008 DECHEMA e.V. ISBN: 978-3-527-31126-2 2 Page Page C 16 Polyurethanes 281 D Materials with special properties 287 C 17 Alkyd resins 282 D 1 Coatings and linings 287 C 18 Epoxy resins 282 D 2 Seals and packings 290 C 19 Fluorocarbon resins 283 D 3 Composite materials 291 C 20 Polyvinylidene chloride 285 D 4 Heat-resistant and scaling- 291 C 21 Amino resins 285 resistant alloys C 22 Silicones 285 D 5 Natural and synthetic elastomers 291 C 23 Other synthetic materials 286 D 6 Powder metallurgical materials 293 E Material recommendations 294 Bibliography 297 3 Survey Table The corrosion behavior of the individual materials was evaluated on the basis of experience gained in practice and the conditions described in the following text. Material Type Behavior** Material Type Behavior** No.* No.* A Metallic materials A 35 Platinum metals +to– (Ir, Os, Pd, Ru) and their alloys A 1 Silver and silver alloys +to– A 36 Tin and tin alloys +to– A 2 Aluminium +to– A 37 Tantalum, niobium, and their + A 3 Aluminium alloys +to– alloys A 4 Gold and gold alloys + A 38 Titanium and titanium alloys + A 5 Cobalt and cobalt alloys +to– A 39 Zinc, cadmium and their alloys +to– A 6 Chromium and chromium +to– A 40 Zirconium and zirconium alloys + alloys A 41 Other metals and alloys + A 7 Copper +to– A 8 Copper-aluminium alloys +to– A 9 Copper-nickel alloys +to– B Non-metallic inorganic materials A 10 Copper-tin alloys (bronze) +to+ B 1 Asbestos + A 11 Copper-tin-zinc alloys +to– B 2 Natural stones +to– (red brass) B 3 Carbon and graphite + A 12 Copper-zinc alloys (brass) +to– B 4 Binders for building materials +to– A 13 Other copper alloys +to– (e.g. mortar and concrete) A 14 Unalloyed steels and cast steel +to– B 5 Acid-resistant building + A 15 Unalloyed cast iron +to– materials and binders (putties) A 16 High-alloy cast iron, +to+ B 6 Glass +to+ high-silicon cast iron B 7 Quartz ware and quartz glass + A 17 Structural steels with up to +to– B 8 Enamel + 12 % chromium B 9 Porcelain + A 18 Ferritic chromium steels with +to– B 10 Stoneware + more than 12 % chromium B 11 Refractory materials + A 19 Ferritic-austenitic steels with +to– B 12 Oxide ceramic materials +to– more than 12 % chromium B 13 Metallo-ceramic materials + A 20 Austenitic chromium-nickel +to– (carbides, nitrides) steels B 14 Other inorganic materials +to– A 21 Austenitic chromium-nickel- +to+ molybdenum steels A 22 Austenitic chromium-nickel +to+ C Organic materials steels with special alloying C 1 Natural fibers (wool, cotton, silk + additions etc.) A 23 Special iron-based alloys +to– C 2 Bituminous compositions + A 24 Magnesium and magnesium +to– (bitumen, asphalt, pitch) alloys C 3 Fats, oils, waxes +to+ A 25 Molybdenum and +to+ C 4 Wood +to– molybdenum alloys C 5 Modified cellulosics +to– A 26 Nickel +to– C 6 Furan resins +to+ A 27 Nickel-chromium alloys +to– C 7 Polyolefins and their copolymers +to+ A 28 Nickel-chromium-iron alloys +to– C 8 Polyvinyl chloride and its +to+ A 29 Nickel-chromium- +to+ copolymers molybdenum alloys C 9 Polyvinyl esters and their + A 30 Nickel-copper alloys +to– copolymers A 31 Nickel-molybdenum alloys +to– C 10 Phenolic resins + A 32 Other nickel alloys +to+ C 11 Acrylic resins +to+ A 33 Lead and lead alloys +to+ C 12 Polyamides +to– A 34 Platinum and platinum alloys +to– C 13 Polyacetals + to – 4 Material Type Behavior** Material Type Behavior** No.* No.* C 14 Polyesters + D Materials with special properties C 15 Polycarbonates +to– D 1 Coatings and linings + C 16 Polyurethanes +to– D 2 Seals and packings + C 17 Alkyd resins +to– D 3 Composite materials + C 18 Epoxy resins + +to D 4 Heat-resistant and scaling- + C 19 Fluorocarbon resins + resistant alloys C 20 Polyvinylidene chloride + D 5 Natural and synthetic +to– + C 21 Amino resins elastomers C 22 Silicones + D 6 Powder metallurgical materials +to– C 23 Other synthetic materials +to+ * Any notes in the text are entered under the same number as the materials, (for example A1, B5, C7) ** + resistant/+ fairly resistant/– unsuitable. Where no indication of corrosion resistance is made, experimental data is not available. 5 Warranty disclaimer This book has been compiled from literature data with the greatest possible care and attention. The statements made in this chapter only provide general descriptions and information. Even for the correct selection of materials and correct processing, corrosive attack cannot be excluded in a corrosion system as it may be caused by previously unknown critical conditions and influencing factors or subsequently modified oper- ating conditions. No guarantee can be given for the chemical stability of the plant or equipment. Therefore, the given information and recommendations do not include any state- ments, from which warranty claims can be derived with respect to DECHEMA e.V. or its employees or the authors. The DECHEMA e.V. is liable to the customer, irrespective of the legal grounds, for intentional or grossly negligent damage caused by their legal representatives or vicarious agents. For a case of slight negligence, liability is limited to the infringement of essential contractual obligations (cardinal obligations). DECHEMA e.V. is not liable in the case of slight negligence for collateral damage or consequential damage as well as for damage that results from interruptions in the operations or delays which may arise from the deployment of the Corrosion Handbook. 6 Sulfur Dioxide Introduction – Physical properties – Sulfur dioxide (SO2) is a colorless, non-combustible, toxic gas. Its most important physical properties are summarized in Table 1. Since the critical temperature is very high, sulfur dioxide can easily be condensed by compression to give a colorless, readily mobile liquid [1, 2]. Properties Value Melting point (101.3 kPa) 197.5 K (–75.65 °C) Heat of fusion (melting point) 115.6 J/g Dynamic viscosity at 273 K (0 °C) 368 Pa s Density at 263 K (–10 °C) 1.46 g/cm3 Critical density 0.525 g/cm3 Critical pressure 7.88 MPa Critical temperature 430.5 K (157.35 °C) Boiling point under 101.3 kPa 263 K (–10 °C) Heat of vaporization (boiling point) 402 J/g Normal density at 273 K (0 °C) (101.3 kPa) 2.93 kg/m3 Relative density based on air = 1 (273 K (0 °C), 101.3 kPa) 2.263 Molar volume (273 K (0 °C), 101.3 kPa) 21.9 l/mol Standard enthalpy of formation –297.2 kJ/mol –4,636 J/g Specific heat cp (101.3 kPa) at 273 K (0 °C) 586 J/(kg K) Specific heat cp (101.3 kPa) at 373 K (100 °C) 662 J/(kg K) Specific heat cp (101.3 kPa) at 573 K (300 °C) 754 J/(kg K) Specific heat cp (101.3 kPa) at 773 K (500 °C) 816 J/(kg K) Table 1: Physical properties of sulfur dioxide [1] Introduction 7 Figure 1 shows the vapor pressure curves of liquid sulfur dioxide as a function of temperature and the dew points of gases with various sulfur dioxide contents under various pressures [1].