SELECTION OF MATERIAL IN ENGINEERING MATERIAL-4.pptx

PPT for selection while constructing any device ,instrument like - jet , car etc .

1. Selection of materials of construction (metals and alloys) for handling different chemicals

2. GROUP MEMBERS Tarun Gaur-CH21181 (Nitric acid) Sweta-CH21180 (acetic acid) Suraj-CH21177 (phosphoric acid) Vishvaranjan-CH21183 ( NaOH ) Suraj Raj Chaudhary-CH21178 (HCL) Sushant – CH21179(SULPHURIC ACID) Vivek Brahma- CH21184(GLACIAL ACETIC) Vikrant-CH21182 Ajit Kumar-CH21109(INTRODUCTION)

3. ABSTRACT There are several techniques for corrosion prevention that may include material selection, environmental alteration, design, coating, and many more. Amongst them, selection of materials is the most common and easiest way which is done once the corrosive environment is characterized.

Corrosive environments include the atmosphere, aqueous solutions, soils, acids, bases, inorganic solvents, molten salts, liquid metals, etc.

Hazardous chemicals and their corrosive nature are studied to select the most suitable metals and the alloys resistant. Chemicals like sulphuric acid, hydrochloric acid, acetic acid, glacial acetic acid, nitric acid, phosphoric acid and caustic soda are chosen for study.

Here, the cost may be a significant factor. It is not always economically feasible to employ the material that provides the optimum corrosion resistance; sometimes, either another alloy and/or some other measure must be used.

4. Factors to be considered in materials selection

5. There are several techniques for corrosion resistance. They are : Selection Design Coating

6. We have to discuss some Chemical- Nitric Acid Sulphuric acid Hydrochloric acid Acetic acid Glacial acetic acid Phospharic acid Sodium Hydroxide

7. SELECTION OF MATEIRALS FOR HANDELING NITRIC ACID Due to its strongly oxidising nature,  HNO3(NITRIC ACID) attacks most metals, causing localized corrosion issues . Exposure to concentrated Nitric acid or acid at a high temperature can cause intense attack in particular areas on the surface of a metal, also known as pitting.

8. Nitric Acid: Stainless Steel Exception Stainless Steel contains about 16-18% of chromium, 10-14% of Nickel, 0.75 % of silicon and other metals. The chromium in stainless steel  reacts with oxygen in the air to produce a protective chromium oxide layer (Cr2O3) across the surface . Although very thin, this layer is what protects the metal from corrosion.

9. The effect of chromium content on passivity

10. Nitric Acid Resistant Materials Charts 304L material is preferable over standard 304 to avoid sensitisation .

11. The iso-corrosion diagram The iso-corrosion diagram 0.1 mm/year lines for the 304 and 316 types coincide, (purple). (The broken line represents the boiling point) This shows that the 304 types can be used over a wide range of concentration and temperature, up to 95%, for storage applications. The 304 types are preferable to 316 types for nitric acid applications however. This is an exception to the ‘general rule’ for stainless steels where the 316 types are normally found to be more corrosion resistant than 304 types.

12. Why Incoloy 825 Is A Powerhouse Against Nitric Acid UNS N08825, also known as Incoloy or alloy 825 , is one of the best metals to use in areas of Nitric acid corrosion. Its chromium content allows a resistance to a variety of oxidising substances, with broad usefulness in higher temperatures. Alloy 825 is used within industries that require all-round hardiness when exposed to strong substances. These industries include the nuclear sector and acid production. The chromium content of 825 is 19.5-23.5, with other elements being 38.0-46.0 Nickel, 0.6-1.2 titanium and 2.5-3.5 molybdenum. The types of corrosion that 825 can withstand include pitting, crevice corrosion, intergranular corrosion and SSC.

13. GLACIAL ACETIC ACID Glacial acetic acid is the trivial name used to refer to pure acetic acid in an anhydrous state. Glacial acetic acid is corrosive poison that can cause injury or death when exposed to human.

14. Metal & Alloy Resistant to its Corrosive Nature Zirconium has been the material of choice since its corrosion resistance to glacial acetic acid is good The presence of molybdenum in INCOLOY alloys 825,020 greatly enhances resistant even to boiling highly concentrated acetic acid

15. SELECTION OF MATEIRALS FOR HANDELING Acetic ACID Acetic acid is the source of many products including fibres, plastics, agricultural chemicals etc.. It is a weak reducing acid. The most popular application of acetic acid is its use in vinegar. It is also extremely useful in the production of the vinyal acetate monomer .

16. Corrosion resistance of stainless steel Ferritic stainless steels such as 430 type can be considered for most acid concentration at ambient temperature but normally the 304 types are used for most applications, including handling and storage. We use 304 stainless steel instead of 430 stainless steel because the probability of pitting corrosion (localised corrosion) is low in 304 stainless steel. But above the temperature 60-70°C and concentration of acetic acid is 80% or more we prefer to use 316 type because there is a risk of localised attack in 304 type stainless steel. Anhydrous acetic acid will increase the corrosion rate, the introduction of a few tenths of one percent of water will reduce the rate of corrosion. 316L type stainless steel is also preferred for bluk shipment. 304 stainless steel is use for storage tank, dilute acetic acid solution of less than 90% concentration.

17. Graph of temperature vs concentration

18. Copper and its alloy show supreme performance in all concentration of acetic acid upto and infact above the boiling point but it now replaced with stainless steel 316 type. Alloy C-276 and its variants are specified for extremely hot acetic acid. Alloy B-2 is used under reducing conditions. But we prefer to use different types of stainless steel because these alloys are expensive. Apart from stainless steel we can use-

19. SELECTION OF MATERIAL FOR HANDLING SULPHURIC ACID (H2SO4) Sulfuric acid is one of the most important elementary substances of the chemical industry. Sulphuric acid shows different character at different concentrations as at higher concentrations greater than 85% the acid becomes oxidizing, there is no stainless steel or even a nickel base alloy available which is suitable over the entire concentration range up to boiling temperature(337°C)

20. CORROSION RESISTANCE OF DIFFERENT MATERIALS. Sulfuric acid is very corrosive . At higher concentrations and temperatures the use of materials like high alloyed stainless steels and nickel based alloys become necessary. :-Alloy 20, :-Alloy 825, :-Alloy 926, :-Alloy 31

21. The nickel based alloys 825 and 20 can be used for temperatures up to approx. 50 °C. • Very diluted Sulphuric acid at low temperature AISI type 304 and 316 steels are used .For components operating at these lower sulphuric acid temperatures various special materials are used, such as :- High-silicon steels, e.g. for acid distribution systems :- High-chromium low carbon stainless steels like alloy 310 L (1.4335) used for plate heat ex-changers (acid coolers) :- Type 316 L Stainless steel has been used successfully for tubular heat exchangers and piping systems

22. Sodium hydroxide (NaOH) is a corrosive alkali, commonly called caustic soda or soda ash. It must be handled with care because it destroys organic tissue and requires protection of the skin and eyes. SODIUM HYDROXIDE

23. Metals and alloys most frequently considered for use in caustic soda are Carbon steel Stainless steels Nickel High nickel alloys

24. Austenitic stainless steels The “18-8”-type stainless steels, exemplified by Types 304 (UNS S30400) and 316 (S31600) and their low carbon equivalents Type 304L (S30403) and Type 316L (S31603), have a useful low corrosion rate in caustic at all concentrations up to about 65°C (150°F) Types 304 and 316 have low corrosion rates in boiling caustic soda at concentrations up to nearly 20%. Type 316 has a better resistance to pitting than Type 304 in caustic solutions. The low-carbon grades perform marginally better than the high-carbon grades because of their resistance to sensitization .

25. Commercially Pure (C.P.) Nickel and its alloys C.P Nickel -— is available in two variants, Nickel 200, and a low-carbon Nickel 201, both of which have excellent resistance to caustic soda, even as the hot anhydrous form Except for silver, nickel is the most resistant metal for high caustic concentrations at the elevated temperatures which generally prevail. At concentrations up to 73% caustic, the corrosion rate is generally less than 0.025 mm/y (1 mpy ). The rates increase slightly above 73%. In most caustic applications Nickel 200 and Nickel 201 are very resistant to caustic SCC at all concentrations and temperatures up to about 290°C (550°F). Though Nickel 200 or 201 are usually most resistant, Alloy 400 and 600 are often used for higher strength.

26. Nickel - Copper alloys Alloy 400 has corrosion resistance similar to C.P. nickel for concentrations up to 73%, although it is susceptible to caustic cracking in severe service. At higher concentrations, the corrosion rate is somewhat greater than C.P. nickel. In lower concentration. Alloy 400 can be useful for caustic service at a lower cost than pure nickel. Alloy 400 components used in handling mercury-cell caustic prior to final separation of mercury and its salts from the product

27. Nickel-chromium-iron alloys Alloy 600 exhibits resistance similar to C.P. nickel up to and including the anhydrous product. It is favoured for heating coils, because of higher strength at temperature than the pure nickel alloys. Alloy 600 offers an advantage, compared to Nickel 201 when a sulphur -bearing contaminant may be present, in being less susceptible to nickel sulphide eutectic formation. It has been used for the production of anhydrous caustic where sulphur was present.

28. SELECTION OF STAINLESS STEELS FOR HANDLING HYDROCHLORIC ACID (HCL ) Hydrochloric acid is classed as a reducing acid and lacks the oxidising properties that stainless steels need to maintain their ‘passive’ corrosion resistant surface layer. The acid is formed as a product of the pitting corrosion mechanisms in stainless steels and so when hydrochloric acid is present in any ‘external environment’ corrosion is promoted . Commercially concentrated acid is around 37wt. %.

29. Pitting corrosion is  a localized form of corrosion by which cavities or "holes" are produced in the material . PITTING CORROSION

30. Corrosion resistance of stainless steels The iso-corrosion diagram 0.1mm/year lines are represented for 316 types, (red), and a 6% molybdenum austenitic type, (green). (The broken line represents the boiling point) An isocorrosion diagram is  a kind of tool used to recognize high-corrosion situations during the design process of equipment

31. SELECTION OF STAINLESS STEELS FOR HANDLING HYDROCHLORIC Phosphoric acid The corrosion resistance in pure phosphoric acid varies with the type of stainless steel and improves with higher alloy content. At higher concentrations 316 is resistant at higher temperatures for any particular concentration i.e. the lines are essentially parallel Type 316L (S31603) is extensively used in the phosphoric acid industry for acid storage, handling and transport of pure acid.

32. Nickel-rich G-type alloys developed specifically for wetprocess phosphoric acid service where chloride and fluoride contamination are present. This family can be called G-Type which comprises alloys G-3, G-30 (N06030), and G-35 (N06035) The high-chromium alloys G-30 and 690 (N06690), approximately 30% Cr, are very resistant.

33. reference Nickel Institute publication No. 10020, ‘Alloy Selection for Service in Chlorine, Hydrogen Chloride and Anon, Corrosion Data Survey (Houston, TX:NACE International, 1985), p. 176.

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