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DIPLOMA THESIS "Organic Coating Respecting Ecosystem"
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| Mattia Geradi |
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Graduate. Mattia Geradi studied at the Liechtenstein Technical College for a degree as industrial engineer. He lives in Switzerland.
The use of EVERLAST®C.A.R.O.L as base- and top-coat on carbon-steel at construction sites results in important financial savings Here some extraits of his diploma thesis:
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| Summary |
Manufacturers follow the general trend to get away from outdated standards and try to produce non-hazardous anti-corrosion paints. Also all solvent-containing products will now have a price increase (eco-tax) from Swiss Franc 2,7.-/kg to Swiss Franc 5.-/kg. New on the market are ecosystem respecting organic primer-systems that only contain a minimal amount of solvents or better are solvent-free.Furthermore these rust-primers are practically free of toxic-heavy metals representing another major factor for the ecosystem . In the following paper several organic, environmental-friendly coatings are being discussed. Based on test results from actual use, several products are beeing rated. This product-comparison shows a definite favorite of choice: "EVERLAST®C.A.R.O.L.". This practical example also explains how with this organic ecosytem respecting coating the costs of application can be reduced. ==================================================
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| Index |
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Picture index VI Index of charts. VI 1.0 Corrosion and Corrosionsprotection 7 1.1 Significance of the corrosion 7 1.2 What is corrosion? 7 1.3 Corrosion protection 9 1.4 Influence of the atmosphere 9 1.5 Measures taken for corrosion protection 11 2.0 Active rust protection 13 2.1 Suitable material-combination 13 2.2 Rust-protection guidelines 15 2.3 Protective measures for corrosive situations 16 2.4 Corrosion inhibitors 17 2.5 Electro-chemical corrosion protection 19 3.0 Corrosion inhibition by passivation 20 3.1 Metallic coatings 20 3.2 Non-metallic, inorganic coatings 21 3.3 Organic coatings 24 4.0 Engineering methods used the in applying of organic ......coatings 27 4.1 Choice of anti-rust primers 27 4.2 Start-up analysis 29 4.3 Relationship between paint and substrate regarding thermal ..... expansion 30 4.4 Heavy-metal substances with anti-corrosion effects 31 4.5 One- and two-component systems 31 4.6 Corrosion behaviour of plain- and low-alloy steel 31 4.7 Effectiveness of anti-rust primers with regard to layer ......thickness 33 4.8 Starter conditions for a coating 35 4.9 Coating procedures 35 4.10 Procedure standards in practice 36 4.11 Economic comparison of various primers 39 4.12 Complexity od construction elements 39 5.0 Environmental-friendly coating materials 41 5.1 Evaporation of solventsl 43 5.2 Health report on organic coatings for use in the ......food-industry43 5.3 Acessment of ecosystem-friendly organic ......coatings 44 5.3.1 Technical leaflet product 1: 46 5.3.2 Technical leaflet product 2: 48 5.3.3 Technical leaflet product 3: 50 5.3.4 Technical leaflet product 4: 52 5.3.5 Technical leaflet product 5: 54 5.3.6 Technical leaflet product 6: 56 5.3.7 Remarks about the ecosystem-friendly organic .........coatings 58 6.0 A practical example : The storage-tank 60 6.1 Description of field of utilisation 60 6.2 Storage tank for the food industry 61 6.3 Current manufacturing procedures 62 6.4 Cost-/usage analysis 64 6.5 Analysis summary 67 6.6 Savings potential for storage-tank 67 6.7 Usage Estimate 71 6.8 Final remarks 72 Annex A: - Price deveopment for Chrome-Nickel alloy steel, Material No. 1.4301 - Price development for carbon-steel - Technical data leaflet storage-tank 6000 Liter - Blue print of storage-tank 6000 Liter Literature index Reference index Statement under oath ==================================================
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| 1.5 Measures taken for corrosion-protection |
Corrosion deals with at least two partners in order to occur: The material it corrodes and the external corrosion medium (weather humidity) as the attacking matter.Both partners form the attacking matter. Since the rusting of a given object is thermo-dynamic conditioned there are only two possibilities to alter the corrosion process:
The anti-corrosion measures are as follows:Figure1 ==================================================
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| 4.1 Choice of anti-rust primers |
The correct choice of anti-corrosion primers starts with the structure of the object to be built. Existing conditions with the environment are taken into consideration during construction with regard to corrosive exposure and operation demand of the steel structure.
The following initial data are to be considered:
These data lead to the starter points: protection material and protection application. Please refer for this to the following diagram: Figure2 ================================================== |
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| 4.6 Behaviour of corrosion of carbon-and/ or low-alloy steel |
Corrosion caused through atmospheric conditions on carbon and/or low-alloy steel develops through an oxygen induced mechanism. A heat-generating chemical reaction occurs whereby oxygen is taken up from the air and the reaction products , iron oxides - the rust- builds up. Rust is the thermo-dynamic stable endproduct of the corrosive reaction. During atmospheric corrosion the following chemistry occurs: 4 Fe + 3 O2 + 2 H2O => 4 FeOOH At least oxygen and water or moisture from the air are necessary for iron to oxidize. It should be noted that at a relative air humidity above 70% a sharp increase in corrosive damage occurs. The 70% contents of air-humidity is therefore considered critical. Figure3 ================================================== |
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| 4.7 Effectiveness of anti-rust primers with regard to layer thickness |
The efficiency of an anti-rust primer depends above all on the protective mechanism of the individual paint product .But also the film-thickness plays an important part: =>Figure4 When treating metal surfaces with an anti-rust coating it is important that the total layer is sufficiently thick. The lifespan H of a protective coating mathematically looks like this: H = tDiff + tinkub + tkorr
The diffusion time [tDiff], which the corrosive medium requires to reach the steel surfaces depends on the diffusion coefficients for the reaction partners (corrosive medium and structure). It also depends on the solubility of the corrosive agent in the coating film the environmental temperature and the protective film thickness. After that the effecting corrosive medium (water, humidity) has penetrated a coating it takes a certain time for incubation (tinkub) for any corrosion to show on the surface.This time delay is due to a certain retarding effect on the steel surface. As soon as the first corrosive elements have penetrated and soaked through the primer and are obviously visible, a rust penetration of the organic coating has occured (tkorr). This "total corrosion time" tkorr is a performance criterium for any anti-corrosion paint. Another factor is the modulus of elasticity of the coating. The more brittle the paint-film, the easier the rust can blast the layer and total rust-infiltration occurs. ================================================== |
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| 4.12 Complexity of construction elements |
When applying an anti-rust primer the complexity of the construction has to be taken into consideration. See the following diagram Table 1 for guidelines. Here relativ complexity of the construction material is indicated for priming ("spraying operation") .
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| 6.2 Storage-tank for the food-industry |
Organic kitchen-waste and food left-overs in a storage-tank are recycable products which in a proper ecosystem can be used in a biological methane-gas generator. here the homogenized food-particles of the storage-tank are being fermented. After the methane gas production is completed the fermented sludge is being composted with other waste of greens. The end-result is a high-potency plant substrate. In this way the energy potential from food left-overs is utilized and what is left from that is recycled in nature. Of course these waste-products do not return to the foodchain for humane for human or animals. Nevertheless it should be considered that an ecosytem respecting organic coating be chosen, because from experience it is not impossible that the waste-products still reach the foodchain of animals, especially pigs.
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| 6.3 Current manufacturing |
Characteristic construction features with regard to corrosion-protection are being taken into consideration and are widely adhered to. Presently a storage tank is being manufactured from stainless steel (material no. 1.4301). A tank with an average storage volume of 6000 litres (6 m3) consists essentially of the following elements:
=> Table 2 |
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| 6.4 Cost-/usage analysis |
In the cost-/usage analysis certain efficiency features are being taken into consideration, which are guidelines for the actual use of the storage-tank. Other factors have no influence on the economic aspect and are not demanded by the customer. The important points are:
The price of a dry coating of at least 150 µm (6 mils) is calculated from the basic paint-price, minimal coating-thickness and the paint quantity. All of the six products described in the preceeding chapter comply with the production demands of an organic ecosystem-respecting coating and can be used for food storage tanks. See=> Table 3 |
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| 6.5 Analysis summary |
The product portfolio Figure5 clearly shows the cost-and usage-advantage in the example of the storage-tank in product No.1. At 11.70 Swiss Francs this product quotes the lowest price and with 30 points (among other things) represents the highest product on the quality scale.
The product EVERLAST®C.A.R.O.L includes all factors necessary for an organic ecosytem-friendly coating. ================================================== |
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| 6.6 Savings potential for storage-tank |
Since the beginning of 1999 the price for steel has escalated. Especially rust free-steel of the material no. 1.4301 quality has had an alarming increase in comparison to non-alloy steel.=> Figure 6 and Figure 7. ================================================== |
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| 6.8 Final remarks |
Many influence are at play. Nevertheless several factors indicate to achieve cost-savings with an organic coating. This change away from the conventional to newer technology stands the test. Even if a storage tank is not exposed to large mechanical stresses and generally not restricted to appearance demands, it is vital that the tank is not damaged during storage, transport to its usage-destination nor during the rust-protection process. Any damage here could lead to a local-corrosion, producing on the container a rapid corrosion damage.
Its perfect condition is important, since the storage-tank will be placed in a basement of a building or underdeck on a ship. The tank will be secured and only with great effort can it be replaced. Therefore careful handling is necessary in order to avoid expense replacements, costs of which can easily run into 10 to 100 times the amount of savings. Comparison testing with different manufacturers of anti-rust products show "EVERLAST®C.A.R.O.L" as the definitive favourite, with convincing efficiency data and cost-reduction regarding the storage-tank. Its qualities are superior and its use multiple. ================================================== |
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| Illustrations |
Figure 1: Choice of corrosion protection measures. Figure 2: Chioce-model corrosion protection. Figure 3: Corrosion impact on iron vs. air humidity Figure 4: Influence of thickness of paint-layer on the corrosion protection ability. Figure 5: Product portfolio of organic coating storage-tank Figure 6: Cost analysis for stainless steel material No. 1.4301. Figure 7: Cost analysis for carbon steel ================================================== |
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| Charts |
Table 1: Degrees of complexity for construction components during base priming. Table 2: Components of 6000 litre storage-tank. Table 3: Efficiency analysis of non-alloy storage-tank cost-quotation for January 2001 |
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| References |
Liechtenstein Technical College Marianum Vaduz Principality of Liechtenstein |
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