Industrial Paints & Protective Coatings Guide · 2018. 5. 10. · (vehicles) and solvents. Pigments. are the solid part of coatings and it is responsible for color, cosmetic ability

Industrial Paints And Protective Coatings Guide

1. Introduction………………………………………………..…..3 2. Coating Selection…………………………………………..…..4 3. Types Of Paints/Coatings………………………………...…...7 • Convertible Cure • Non-convertible Cure • Zinc-rich Coatings 4. Surface Preparation……………………………………..…...21 • Surface Conditions • Surface Preparation Of Concrete Surfaces • Surface Preparation Of Metallic Surfaces 5. Application Methods & Tools……………………………….31 6. Mixing & Thinning Of Paints/Coatings…………………....33 7. Measurement Of (Wet & Dry) Coating Film Thickness….35 8. Basic Coatings Inspection…………………………………...39 9. Coatings Failure − Causes & Prevention…………………..46 10. Hazcom & Safety…………………………………………….56 11. Product Selection Guide…………………………………….77 12. Glossary………………………………………………………83 13. Full Service Support…………………………………………96 14. Reference……………………………………………………..97

Industrial Paints & Protective Coatings Guide 3

Materials such as concrete and carbon steel are cheap, excellent construction materials which if exposed to an aggressive environment may not be fully durable over the intended life of the structure. Consequently they must be either replaced or protected by the application of a suitable coating system.

Generally, replacement of cheap bulk materials with chemically resistant but more expensive materials is not economically viable, indeed it may not be possible to obtain replacements in sufficient quantity. Design requirements may limit section thickness and any deterioration of the bulk material is often unacceptable e.g. for aesthetic reasons.

Coating systems offer a cost effective means of protecting a new structure from an aggressive environment. As it can be constructed using cheap bulk materials and subsequently protected by the thin (more expensive) outer coating.

Coating systems can also be used as part of a remedial scheme for materials which are already deteriorating.

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2. Coating Selection

Coatings can be used to protect a substrate in a number of ways. They can form an impermeable barrier between the environment and substrate and afford almost complete protection. Coatings also protect the substrate by slowing the rate of penetration of aggressive components from the environment into it. Coatings may be used for decorative purposes, though the presence of a coating will generally provide some protection to the substrate.

Structural requirements, service environment, aesthetic appear-ance and cost must be considered before selection.

Some factors to be considered in selection are presentable in the following table:

Feature Consideration

Original Substrate Construction material, steel, concrete, etc. New construction or remedial work. Condition. Presence of an existing coating. Surface contamination.

Environment Atmospheric, marine, buried, etc. Presence of moisture, aggressive chemicals.

Coating durability Adhesion, UV resistance, water resistance, chemical resistance, impact resistance, elasticity, film hardness, abrasion resistance, toxicity (where it will come into contact with potable water), dirt pick-up, color retention.

Application features Surface preparation requirements. Brushing, spraying characteristics. Tolerance to substrate moisture. Temperature dependence. (application & curing). Site access.

Cost Unit material cost, unit of coats required, film thickness, labor costs, maintenance costs.

Industrial Paints & Protective Coatings Guide

5

The decisions required for coating selection for both new and det-eriorated structures are shown in the following figures.

New construction

Characterize current and future service environments.

Do structural materials require

additional protection?

Characterize substrate surface and select appropriate cleaning methods.

Yes

Do nothing.

Review performance requirements for the coating.

Select a surface coating or chemically resistant membrane as appropriate.

Is the solution cost effective?

(including maintenance requirements)

No

No

Apply coating system.

Figure 1. Selection of a coating system for new construction.

Yes


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Figure 2. Selection of a coating system for a deteriorating construction.


Deteriorating substrate.

Characterize current and future service environments.

Establish cause and extent of deterioration.

Is structural Integrity

Impaired?

Will a coating arrest

deterioration or prevent structural

integrity being Impaired?

Replace member or undertake structural repair.

Yes No

No

Do structural materials require

additional protection?

Is the solution cost effective?

(including maintenance requirements)

Characterize substrate surface and select appropriate cleaning methods.

Do nothing.

Review performance requirements for the coating.

Select a surface coating or chemically resistant membrane as appropriate.

Apply coating system.

Yes

No

Yes

No

Yes

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3. Types Of Industrial Paints/Protective Coatings

A large number of coatings to protect structural materials from the many different service environments are available & choosing the right one is difficult. The following sections describe many of the coatings, their performance and application.

3.1 Convertible Cure

The main constituents of coatings are pigments, fillers, binders (vehicles) and solvents.

Pigments are the solid part of coatings and it is responsible for color, cosmetic ability and reinforcement. Pigment particles play a part in giving the coating the correct consistency and also protect the binder from UV-light.

Fillers give the coatings the correct consistency for spraying, rolling or brushing and allow the application of thick coatings without sagging and also they provide the coatings film with mechanical reinforcement.

Binders (vehicles) are the liquid portion of the coatings that carries the pigment and fillers to the surface and forms the film (film former).

Solvents provide the appropriate viscosity for application.

Because of health and safety, there is an increasing interest in solvent-free and water-based coatings.

Curing mechanism is the way a coating is transformed from a liquid to a solid, dry material.

There are two curing mechanisms, the first one is “convertible cure” which is a chemical reaction occurs n the coating film as it cures. When the chemical reaction is complete, the film is cured. After curing, a strong solvent can not re-dissolve the coating.


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3.1.1 Oxidation (oxygen induced polymerization)

Initially, solvent (or water) evaporation occurs because solvent or water are a part of the coating. After solvent evaporation, the resins undergo a chemical change known as curing. After drying, the resins cure by a cross linking reaction called (polymerization). Three different cross linking mechanism are oxidation, co-reaction and hydration.

After curing, a strong solvent will not re-dissolve the coating.

Oxidation cure coatings cure by reaction of the resin with oxygen from the air. The oxygen forms a cross link between resin molecules, as it proceeds, the molecule become much larger. Throughout this process the solvent is evaporating from the coating. Once all the solvent has evaporated from the film and the long chains have become tangled and are locked into position, the coating is dry. Heat is sometimes used to speed the curing process.

Because oxygen in the air can enter the film only at the surface, the coating film thickness must be limited (3-5 mils) to prevent the coating film to pucker and wrinkle at the top and require longer time for the film to turn into a solid at the substrate.

Oxidation cure coatings include:

Drying oils. Alkyds.

Epoxy esters. Phenolic [oil modified].

Silicon alkyds Urethane [oil modified].

3.1.1.a Drying oils or wetting oils

Drying oils are obtained from plants as (linseed, caster, soybean) and from certain species of fish.

These oils are used with synthetic resins as (alkyds) using heat.


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Advantages of dry oils are;

• The ability to wet and penetrate the surface.

Disadvantages are;

• Slow to dry.

• Lack of gloss.

• Sponification in contact with alkalis (ph 8 or more) as in concrete.

• Moisture & chemical resistance are poor.

3.1.1.b Alkyds

Alkyd coatings are oil modified resins that dry to a tough hard film as fast drying enamels.

Advantages of alkyds are;

• Minimal surface preparation.

• Ease of application.

• Ease maintenance.

• Excellent durability & flexibility. • Low cost.

• Good gloss retention.

Disadvantages of alkyds are;

• Variable color retention.

• Limited film thickness (max. 8 mils).

• Poor heat, chemical and solvent resistance.

• Poor water resistance.

They are used for both interior & exterior (architectural & industrial) coatings on wood, steel or concrete but over an alkali resistant primer or sealer.


Alkyds are used for interior & exterior.

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3.1.1.c Epoxy Ester

They are epoxy resins modified with oil to produce a one-pack coating. Epoxy esters are superior to alkyds but not as hard as co-reacted epoxies.

3.1.1.d Oil Modified Phenolic

They are phenolic resins modified with oil. They are used for both interior and exterior jobs because they have a good resistance to water and chemicals. Phenolics discolor with time, becomes hard and brittle. It is difficult to recoat unless the surface is roughened.

3.1.1.e Oil Modified Urethane

They are urethanes modified with oil. They are available as clear varnish or pigmented coatings. They are abrasion resistant, have good gloss retention and weatherability.

It is used for wood floors, furniture and marine industry.

3.1.2 Co-reaction

Co-reaction coatings are produced by reaction of base & hardener (curing agent) where long chains are formed by chemical cross linking. There are different kinds of co-reaction coatings:

• Epoxy (two components). Coal-Tar epoxy.

• Epoxy mastic. Phenolic (epoxy modified).

• Epoxy emulsions. Urethane (two components).

• Polyester epoxy. Vinyl wash primer.

• Polyesters/Vinyl esters.


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3.1.2.a Epoxy (two-component)

The most common co-reactants are polyamines and polyamides. Epoxy coatings provide a good chemical, solvent and water re-sistance. It can create a thick dry film. Most of epoxies chalk when exposed to UV-light.

3.1.2.b Epoxy Mastic

It is a high solids two part epoxy coatings. They have good wet-ting ability and can be applied in thick coat (5 mils). Dry film thickness in a single coat. They are often used as primers. They have a good chemical and moisture resistance.

3.1.2.c Coal-Tar Epoxy

Coal-tar is a by-product of coke industry. Refined coal-tars are combined with epoxy resins. The black tar reduces permeability of the epoxy film. It provides excellent protection to steel and concrete in water immersion & sub-soil. It is used in coatings of tanks, pipelines, ocean and river docks, marine industry, sewage and water plants and oil refineries. It is difficult to repair and recoat coal-tar epoxies and it has a short pot life.

3.1.2.d Epoxy Emulsions

These are water-based coatings as acrylic epoxy and epoxy poly-amide emulsions. It is durable as solvent-based coatings with added value of low solvent odour. The epoxy resins & usually a polyamide hardener are emulsified as small particles in water. The film formed by coalescence (emulsified particles join together upon water evaporation). As they join together, they crosslink to form a hard film.


Sewage treatment.

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3.1.2.e Polyester Epoxy

Polyester resin is combined with epoxy resin & chemically cross-linked with a co-reactant. Polyester epoxy have an excellent weather resistance but less resistant to chemicals and solvents. They are generally used for cosmetic coatings.

3.1.2.f Urethane (two-component)

It is formed by the reaction of isocyanides and a co-reactant as (acrylic, polyester or epoxy). They are available in two varieties:

Aliphatic Urethane:

They are abrasion resistant, chemical resistant, hard, flexible, and have a good exterior gloss and color retention.

They have a limited pot life. They are used for all heavy industrial applications and environments.

Aromatic Urethane:

They are much like aliphatic urethanes, but they can be used in immersion service. They yellow on exposure to UV-light.

Premature opening of the containers can lead to deterioration and premature coating failure.

3.1.2.g Polyesters/Vinyl Esters

They are initiated by a catalyst, com-bined with a co-reactant as styrene to form a cross linked resin. They have a high film thickness (up to 80 mils). These coatings have excellent chemical resistivity against acids, solvents and water. They are also heat and abrasion resistant. They are used for tank lining and chimneys.



High-build solvent-containing epoxy coating have been used on several structures.

Both carbon tetrachloride tanks were painted 4 years ago; discolored tank at left, with rust, has epoxy topcoat; tank at right has aliphatic urethane finish.

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3.1.2.h Phenolic-Epoxy Modified

Phenolic resins are modified with epoxy resins & cured by amine co-reactant. They are used for interior tank lining (max. 20 mils), pipelines and nuclear power plants. They are solvent and water resistant.

3.1.2.i Vinyl Wash Primer

It consists of rust inhibitive pigment (zinc chromate), a polyvinyl alcohol resin and a phosphoric acid. This coating is used to pro-vide adhesion and corrosion inhibition between the metal surface and some coatings as (alkyd, epoxy, urethane). The wash primer should be applied not thicker than ¾ mil d.f.t.

It is a fast drying and curing (15 – 20 minutes), it should be recoated within four hours. It is also has a limited pot life.

3.1.3 Hydration

Hydration occurs when water combines chemically with the coating, concrete, other cementitious materials, moisture cured urethanes and some type of inorganic zinc coating.

3.1.3.a Cementitious Materials & Concrete

Concrete is inorganic corrosion resistant coating for steel. It creates an inhibitive, highly alkaline environment which prevents steel corrosion. Cement mortar is used as a lining for steel pipes. Concrete is unaffected by sunlight, weather and moisture.

Concrete coatings are bulky, heavy and attacked by acids, fungi and bacteria.


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3.1.3.b Urethane (Moisture Cure)

Moisture cured urethanes cure by reaction with moisture in the air. The air must have a relative humidity between (30 – 80 %) to cure properly. It has an excellent toughness, flexibility, resistance to abrasion and solvent, acids and alkali resistance. It has a limited pot life once it is opened. it is used for wood and concrete.

3.2. Non-convertible Cure

No chemical reaction occurs. After the coatings film forms, a strong solvent can re-dissolve the coating. There are two types of non-convertible coatings; those that dry by solvent evaporation and those that coalesce.

3.2.1 Solvent Evaporation (Lacquer Dry)

These coatings that cure by solvent evaporation are formed by dissolving a resin in solvent. The coating cure by simple evapor-ation of solvent. When used in a multiple-coat system, these types as (vinyl over vinyl) fuse to form a single solid film. These coatings should not be top coated with a different type of coating containing a strong solvent. It should be applied in small thickness to allow solvent to evaporate common coatings which cure by solvent evaporation include coal tar, chlorinated rubber, asphalt and vinyl.

3.2.1.a Coal Tar (Thermoplastic)

The main ingredient of this type is coal tar pitch which is produced from coal tar recovery in the coke industry. Coal coatings have excellent water resistance so that they are used as a corrosion resistant coatings on underground or underwater steel or concrete.


16 Industrial Paints & Protective Coatings Guide

it is not resistant to UV-light. It can be produced as enamels, emulsions and cutbacks.

Hot applied coal tar (enamels) consist of pitch & filler. It is heated and applied in a molten form to be used e.g. in pipelining.

Cold applied cutbacks are made by reducing the pitch with a suitable solvent. The dry film thickness will vary from (2-18 mils). They are self-priming coatings.

3.2.1.b Chlorinated Rubber

It is manufactured by the reaction of rubber with chloride. The resin is pig-mented & dissolved in a suitable solvent. It is used for swimming pools, chemical plants, water treatment plants, or wherever resistance to water, acid & alkali is required. It has a poor solvent resistance, oils & fats. It will not tolerate exposure to temperature exceeding 150˚ F (65˚ C) for long periods.

3.2.1.c Asphalts

These are dark colored, petroleum-based, thermoplastic coatings. It has a good moisture resistance. It is often used for driveways, roofing and anti-corrosive coatings. It comes in three forms:

Enamels: These are solid at room temperature. They must be heated to 500˚ F (260˚ C) for use.

Emulsions: These are small asphalt particles in a water-based vehicle.

Cutbacks: These are liquid solutions of asphalt in volatile solvent. Asphalt coatings should not be applied to surfaces with a temperature (< 5˚ C).

Chemical plant.

17 Industrial Paints & Protective Coatings Guide

3.2.1.d Urethane (Moisture Cure)

Vinyl coatings form a very tight film. These dense, continuous film is strong, resistant to many chemicals & salts and unaffected by water exposure. It is used for marine exposures, chemicals and paper plants, petroleum refineries, food processing, water and sewer plants.

3.2.2 Coalescence (Latex Dry)

Latex emulsions are made of finely divided particles of resin and pigment suspended in water. A small amount of slowly evapo-rating solvent is also mixed into the emulsion. As water evaporates, the solvent partially dissolves the resin, the particles come into contact and stick together to form a dried film. These coatings are thinned and cleaned with water. They varied in hardness, flexibility and gloss. The common types of these latex coatings are acrylics, vinyl acetates, vinyl acrylic, styrene butadiene. Latex coatings are not suitable for severe chemicals environments or immersion service. Latex coatings should not be applied in cold, humid, moisture, rainy or hot environments. A minimum application temperature is 50˚ F (10˚ C). These coatings are easy to apply, contain no solvent, fast to dry and cause no fire hazard.

3.3 Zinc—Rich Coatings

These coatings contain large amounts of zinc dust (zinc metal) as the pigment. The zinc dust particles are held together and to the surface by small amounts of binder.

This high volume of zinc allows metal-to-metal contact. The result is galvanic protection for the steel. Zinc rich coatings contain a high volume of zinc pigment (75% - 95%) by weight of zinc dust in the dried film.

Food processing.


The binders are organic as epoxy and urethanes and inorganic as silicates. All zinc coatings are used as a primer or a single-coat systems. Zinc coatings are used to protect power plants, chemical processing plants, paper mills, offshore plat forms, ships, bridges and other steel structures.

3.3.1 Inorganic Zinc Coatings

Inorganic zinc coatings consist of zinc metal mixed into a silicate solution such as ethyl silicate, sodium silicate, potassium silicate and others. the silicate solution cures by different means:

The addition of acid or heat.

Reaction with carbon dioxide and moisture.

Hydrolysis.

3.3.1.1 Water Base, Post Cure Inorganic Zinc coatings

These coatings cured by the application of heat or acid solutions. These coatings are difficult to apply but they provide the longest corrosion protection. They can be applied under cool or warm, dry conditions. These coatings are water-based so they can be used wherever water will evaporate.

These coatings cure by neutralization & crystallization after water evaporation from the coating. The alkali silicate reacts with carbon dioxide and moisture from the air. These coatings work best when applied under cool, humid conditions.

They cure much slower than post-cure coatings. Full cure of these coatings take (3 − 4 days) at relative humidity > 60% before applying top coatings.

3.3.1.2 Water Base, Self Cure Inorganic Zinc coatings


3.3.1.3 Solvent Base, Self Cure Inorganic Zinc coatings

These are solvent-reducible, depend on moisture in the air to complete hydrolysis and to form a cured coating. In hot dry climates, there may not be enough moisture for curing, water can be sprayed on the coatings to cure. The most common type of these alkyl silicate is ethyl silicate.

These inorganic zinc-rich coatings are characterized by the following:

• Provide cathodic protection to steel

• Unaffected by high temperature (400˚ C).

• Unaffected by organic solvents.

• Limited chemical resistance.

• Form a hard, abrasion resistant film.

• Unaffected by environmental conditions.

3.3.2 Organic Zinc Coatings

Organic zinc coatings contain a high quantity of zinc dust pigment and binders as (epoxy, urethane and vinyl. They provide galvanic protection to steel.

3.3.2.1 Organic Zinc—Rich Coatings (Convertible)

They are organic binders that cure by a chemical reaction as epoxy zinc-rich and urethane zinc-rich.


3.3.2.2 Organic Zinc—Rich Coatings (Non-convertible)

They are organic binders that dry by solvent or water evaporation but do not cure or cross link as vinyl zinc-rich. Upon solvent eva-poration, the resin dries and holds the zinc particles together and to the steel surface. These organic zinc-rich coatings have the following characteristics:

Provide cathodic protection to steel.

Easy to apply.

Easy to top coat.

Abrasion resistant.

Solvent resistant.

Affected by environmental conditions according to binder resistance.

Zinc-rich coatings must be applied to blast cleaned surface to provide metal-to-metal contact so that galvanic protection is attained. Most zinc-rich coatings are to be applied at a dry film thickness from (1.5 – 4 mils). Mud cracking and loss of adhesion can occur in case of greater thickness. The ideal temperature for application is (15 - 30˚C). If the surface is too cold, solvent or water evaporation may be retarded and if the surface is too hot, solvent may be evaporate before a good adhesion is achieved.

Thorough mixing by mechanical agitation is important to provide smooth, lump-free film. While hand mixing can produce a porous film which will become brittle and easy to crack. Avoid shaking because it can cause rapid heating resulting in gel formation or can bursting. All zinc coatings should be applied by spraying and brush application should be limited to small areas or touch-up. Overspray should be avoided to prevent poor adhesion with top coats. Before top coatings is applied, it is better to brush off followed washing to remove surface pollutants as dirt, oil and zinc salts.


Top coatings of zinc-rich must wet & penetrate the porous (open) zinc film to get good adhesion.

Types of coatings are oil-free top coats, it is better to use top coats of the same generic types as primers, e.g. ,epoxy top coat is recommended over epoxy zinc-rich primer, other types are urethane, vinyl and coal-tar epoxies.

4. Surface Preparation

Coatings are applied to industrial structures for corrosion protection and appearance. For a coating to protect, it must be applied correctly. Surface pre-paration is critically important to achieve a successful coating application. Surface preparation is cleaning and preparing a surface to accept a coating. This involves:

Cleaning The Surface: Removing dirt, oil, grease, old coatings, mill scale, rust, weld spatter, salts & other contaminants.

Repair: Eliminating or repairing fabri-cation surface defects. Correcting design defects.

Surface Roughening: To provide a profile or anchor pattern for coating adhesion.

4.1 Surface Conditions

Initial surface conditions are conditions of the surface before doing any surface preparation. These include damage, mill scale, dirt, grease, and design & fabrication defects. All these must be corrected for the coating to work properly.

Removing dirt.


Mill Scale:

It is formed on steel when it is hot rolled. It is a crust with a blue or red-blue, shiny appearance, also it is brittle.

When mill scale comes into contact with moisture, it will lose adhesion. It must be removed before coating. It can be removed manually by blast cleaning.

Rust:

When steel is exposed to oxygen, it changes back to its original form, iron ore. This is rust, it appears as brown or reddish brown patch on steel. It must be removed manually or by blast cleaning before coating.

According to SSPC—Vis 1 standard, there are four conditions of new or existing steel:

A) Steel surface completely covered with adherent mill scale with little, if any rust (SSPC—Vis 1 Rust Grade A).

B) Steel surface which has begun to rust, and from the mill scale has begun to flake (SSPC—Vis 1 Rust Grade B).

C) Steel surface which most of the mill scale has rusted away or from which it can be scraped, but with little pitting visible (SSPC—Vis 1 Rust Grade C).

D) Steel surface where the mill scale has rusted away and where pitting is visible (SSPC—Vis 1 Rust Grade D).

Soluble Salts:

A chemical salt can dissolve in water as sodium and ferrous sulphate. Sodium chloride is often found on surfaces to be coated, especially in marine environment.

Ferrous sulphate occurs as a result of the reaction of the steel surface with airborne sulphur which is found in chemical plants, paper mills and oil refineries. These chemical salts can be spread over the steel surface as a thin layer. If not removed, it can cause premature coating failure by osmotic blistering.


Marine exposure, rain and other elements can leave salt behind. When coated over, salts attract moisture causing rust under the coating. Both of steel is damaged by under film rusting and the coating itself damaged with blistering. Water flushing is used to remove soluble salts, and since removal of all salts is not always possible. Water blasting may be necessary.

Grease, Dirt & Other Residues:

All these residues and other contaminants are in the air, and collect on a surface during handling and fabrication.

These contaminants are visible, they must be removed before coating. Methods of removal are detergent cleaning, alkali cleaning, chemical cleaning solvent cleaning and steam cleaning.

Old Coatings:

Many structures have old coatings on their surfaces that may need recoating. The old coatings may be chalking, flaking, peeling and rust may be showing. Also it may be brittle and have a poor adhesion. All poorly adhered coatings must be removed before new coatings are applied.

Loose coatings can be removed by hand or power tool cleaning or blast cleaning.

Feathering is necessary to eliminate a sharp edge at the interface between the old coating and the new one.

Design Defects:

Design defects must be corrected so that the coating can be applied properly.

If some areas can not be coated, good protection will not be achieved. Common design defects include:

Inaccessible Areas:

The size and shape of some areas make them hard to clean and coat as in areas close to corners & bolt heads. These areas should be cleaned as well as possible.


Rivets, Bolts & Threads:

These areas cause increased surface area and result in areas hard to clean and coat.

Gaps:

Gaps are structural designs beyond the control of the coating applicator. It should be cleaned and coated as specified.

Dissimilar Metals:

When two metals are in contact, one of the metals can rust faster at the point of contact.

Fabrication Defects:

These defects include crevices, skip welds, laminations and sharp edges. Some fabrication defects as weld sag, loose weld spatter and surface laminations should be removed.

Other surface defects may not be visible until after surface preparation has been done as deep corrosion pits & weld voids.

Skip Welds:

Successive welding make coating difficult because air & moisture cause rapid rusting between the welds. Rust must be removed in skip weld areas.

Weld spatter:

Weld spatter and slag should be removed before blast cleaning. Most weld spatter can be removed using hand or power tools. Tightly adhered weld spatter should be removed with blast cleaning.

Rough Welds:

Rough welds are imperfections in the welding that make con-tinuous coating difficult include voids, sharp edges and ridges.


Lamination:

It is occurred as a result of nicks or scratches in the rollers used to form metal plates or structural shapes.

Sharp Edges:

Coatings tend to pull away from edges, leaving a thin coat. This makes edge areas are susceptible to rusting. A stripe coat is good protection for edges. A stripe coat is an extra coating to build up thickness.

Porosity:

Porous areas are problem because rust forms in the pits of the pores. Brushes are better to be used for coating.

4.2 Surface Preparation Of Concrete

Concrete is coated for protection and decoration. Before coating, the concrete surface must be prepared properly. Concrete surface must be clean, smooth and free from dirt, oil, grease and free of the following problems:

Laitance: A milky white deposit on new concrete. It is weak layer of cement-water rich mixture.

Efflorescence: Salts formed by moisture passing through the concrete, when they react with the Co2 in the air, they create a fluffy white deposit on the surface.

Form Release & Curing Agents: Form release agents applied to the form that hold poured concrete in place. Curing agents are waxy components applied to stop moisture of concrete from evaporation too quickly.

Efflorescence.


Methods Of Surface Preparation Of Concrete

There are several methods used for surface preparation of con-crete including:

Abrasive Blast Cleaning:

Abrasive blast cleaning provides a roughened surface and removes extra and spattered concrete. It is the only acceptable method for removing membranes, curing agents, form release agents and to open the concrete surface to improve the anchor pattern of the surface, allowing good coating adhesion.

Hand & Power Tool Cleaning:

This process can vary from simple dust removal to removal of cont-amination or old coatings. Hand and power tools can remove loose, powdery, weak coatings. Grinding and wire brushing are somewhat successful in opening surface voids and for better adhesion.

Hand and power tools are commonly used on small confined areas.

High Pressure Water Cleaning:

Water cleaning at 100 bars or more is used on concrete surfaces. It does not open voids nor provide a profile. Wet abrasion blasting can also be used.

Acid Etching:

Acid etching uses a dilute acid (10% - 15% μ uriatic acid) to remove laitance, spattered concrete.

μ uriatic, phosphoric, citric and sulphonic acids can be used.

Citric and phosphoric acids are used when the acid may contact metal surfaces. Lime water can be used for neutralization followed by a fresh water rinse.

When diluting the acid, always add the acid to water.


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Abrasive Blast Equipment.

Hand & Power Tools.

Wet Blasting.


4.3 Surface Preparation Of Metallic Surfaces

Coatings are applied to industrial structures for corrosion protec-tion and appearance. For a coating to protect, it must be applied correctly. Surface preparation is important to achieve a successful results.

Surface preparation is cleaning and preparing a surface to accept a coating. It involves cleaning of the surface, repair of defects and roughening the surface.

Solvent Cleaning:

This method is used to remove oil, grease, dirt and soluble salts. There are many solvents and cleaners used. Solvents are always used with rags and brushes. This method needs a lot of safety precautions.

Hand Tool Cleaning:

Hand tool involves cleaning hand-held tools to remove mill scale, rust and old coatings. Common hand tools include wire brushes, chipping hammers, scrapers, chisels and sand paper.

Power Tool Cleaning:

Power tool cleaning uses hand-held power tools to remove mill scale, rust, weld spatter, old coatings and other brittle materials. There are three major types of power tools:

Impact cleaning tools which strike the surface and make the contaminants loose. Common types include needle scalers, chip-ping hammers and power scalers.

Rotary cleaning tools which clean by brushing, grinding and sanding. Common types include wire brushes, grinding wheels and abrasive discs.

Rotary cleaning tools which use a spinning wheel with cutters or hammers that strike the surface. Common types are rotary hammers and cutter bundles.


Steel where mill scale has started to flake & light rusting occurs.

Steel where all mill scale has flaked off & complete rusting has taken place.

Steel where pitting & complete rusting has occurred.

Brush-Off Brush-Off Brush-Off

Commercial Commercial Commercial

Near-White Metal Near-White Metal Near-White Metal

White Metal White Metal White Metal


Internal pipe cleaning.

Cleaning with needle scalers.


Water Blast Cleaning:

This method uses a high pressure water to prepare surfaces. It removes rust, flakes, scale, old coatings and other contaminants. Abrasives can be injected at the blast nozzle to increase the cutting power and to provide a surface profile on the surface.

Abrasive Blast Cleaning:

This method propels abrasive particles at high speeds against the metallic surfaces to be cleaned and etched. The highest degree of cleaning can be achieved by abrasive blasting if the necessary pre-cleaning steps are performed such as flushing with water.

5. Application Methods & Tools

Coatings are applied to structures for protection and appearance. Proper application assures a high quality job.

There are application methods for different types of coatings and jobs.

There are different coatings application techniques as follows:

Brush & roller application.

Conventional air spray.

Airless spray.

Hot spray.

Plural component spray.

Electrostatic spray.


Brushes

And

Rollers.

Airless Spray


6. Mixing & Thinning Of Coatings

Coatings are made of pigment and vehicle. Vehicle is resin and solvent which is the liquid part of coatings and pigment is the solid part. In storage, the coating may separate, the pigment sometimes settle at the bottom of the container. Thin layers of skin sometimes form at the surface. Lumps can form throughout the coatings.

Mixing makes the coatings consistent and uniform. Thinning is used to reduce the viscosity.

6.1 Mixing

Mixing is needed for every application of the coating. Proper mixing assures an ever color and texture. Mixing can be done by hand with stirrer or paddle, and by boxing (pouring the coating from one container to another). Mechanical mixing is done with electric or air power mixers or with a mechanical coating shaker. Before any mixing, loosen all settled pigment and completely remove any skin on the coating.

Mechanical mixing is the most common and efficient method. It should be used at the lowest speed possible to avoid vortex. High speed draw in air and cause foaming.

Mechanical coating shakers are used for quantities 5 gallons or less without opening the cans. They operates by shaking vigorously.

One component coatings can be mixed in the can, if the can is full, pour some of it in another can, mix both portions, then add them together.

Two components coatings (A & B), mix each component by itself first, then mix them according to the supplier instructions. Straining after mixing is better to eliminate lumps.


Different types of mixers.


6.2 Thinning

Thinners are used to reduce the viscosity of the coating. They affect film formation, consistency, leveling, drying, adhesion and durability. Each type of thinners should specified and quantified according to the type of coating.

Over thinning can cause runs and sags, it may be also difficult to obtain the specified dry film thickness. Some typical thinners are mineral spirit, turpentine methyl ethyl ketone, xylene & alcohols.

Areas of mixing and thinning must be protected from spillage.

7. Measurement Of (Wet & Dry) Film Thickness

The wet film thickness allows to estimate the dry film thickness.

7.1 Use Of W.F.T Gauge

The wet film thickness gauge has two end points on the same plane with deeper notched steps in between. Each step is given a number representing the distance in mils (mil= 25.4 microns) between the step and the plane.

Press the gauge into the wet film down to the surface being coated. Lift the gauge straight up. The coating will wet the two end points and some of the steps in between. The wet film thickness is between the last wet step and the next higher dry step. If the steps are not wet at all or all steps are wet. Turn to a lower side if no steps are wet, and to a higher side if all steps are wet. Do not drag the gauge across the surface.

Take the readings as soon as possible after the coating is applied.


Wet Film Thickness Gauges.


7.1.1 Limitations

Do not use the W.F.T gauge on any surface with irregularities. On curved surfaces, make readings along the length of the curve.

Do not use W.F.T gauge with cementitious or inorganic zinc coatings.

7.1.2 Maintenance

Using a solvent, wipe the gauge clean of all coating after each use. Bent or worn steps on the gauge give inaccurate readings.

7.2 Dry Film Thickness

Once the coating s applied and dried, it must be inspected for film thickness.

Readings of 10% of the total area is enough. Dry film thickness gauge are:

Non-destructive gauges.

Destructive instruments.

7.2.1 Non—Destructive Gauges

Non-destructive gauges do not destroy the coatings being tested.

Common types of non-destructive gauges are:

Magnetic pull-off.

Magnetic fixed probe.

Eddy current fixed probe.


Dry Film Thickness Gauges.


7.2.2 Destructive Instruments

Destructive dry film thickness instruments destroy a part of the coating film being measured. Once it is taken, touch-up must be done.

The most common destructive dry film thickness instruments is the Tooke gauge or the coating inspection gauge.

7.3 Relation Between Wet & Dry Film Thickness

Wet film thickness =

If thinner is added,

Wet film thickness =

D.F.T

% Volume Solids

D.F.T X (1 + % Thinner)

% Volume Solids

8. Basic Coating Inspection

Inspection is necessary to get a quality coating application within the specifications. It should be done during surface preparation, coating application and during the life of the coatings.

The inspection should cover the following:

Surface preparation equipment.

Environmental conditions.

Surface profile & cleanliness.

Coating inspection & testing.

Tooke Gauge


8.1 Surface Preparation Equipment Testing

The applicator should be familiar with several tests to assure pro-per conditions and the use of equipment at site.

8.1.1 Blotter Test

This test checks for oil and water contamination of the blast sys-tem. It is done by spraying compressed air only onto a blotter to check for cleanliness.

8.1.2 Sieve Test

This test is to check for abrasive size. A balance and a set of NIST screens are used.

A quantity of abrasive is weighed, then poured into the top of the screens. The screens are shaken over a pan. The particles stuck at each sieve is to be weighed. Then calculation of the percentage of each size is done.

8.1.3 Vial Test

A sample of abrasives is scooped into the jar or vial and some distilled water is added, the mixture is shaken. If oil is present a film appears on the water and if the water clouded with dirt, the abrasive is contaminated. Litmus paper indicate the presence of some water soluble salts.

8.1.4 Soluble Chemical Salts Test

The chemical salts can be spread over the steel surfaces as a layer so thin, it can not be seen. If not removed, it can cause pre-mature coating failure (osmotic blistering). These salts are hygro-scopic, they attract water. There are several tests available to de-tect these salts, if present on the steel surface.

A qualitative test for a soluble chemical salts can be done by wetting the surface with water and press the test paper. If the color changes, this indicates the presence of salts. To estimate the quantity of the salts a quantitative test is performed.


8.1.5 Nozzle Air Pressure Test:

This test is also called (the needle gauge), test to measure the air pressure at the nozzle.

8.1.6 Nozzle Throat Test:

As an abrasive blast nozzle is used. The abrasives wear down the lining. This increases the diameter of the throat of the nozzle and decrease the efficiency. The nozzle throat should be checked everyday by means of nozzle gauge.

8.2 Environmental Conditions Tests

Ambient conditions are the environmental conditions during the coating application. They include temperature of air & steel surface, humidity and wind speed. Ambient conditions affect coating application.

Ambient air temperature is the temperature of the air around the structure’s surface.

Surface temperature is the temperature on the structure’s surface.

Relative humidity is the percentage of water vapor in the air at a given temperature. The dew point is the temperature which water will condense.

Ambient conditions are measured with psychrometers. There are two common psychrometers:

• Sling pyschrometer.

• Fan operated pyschrometer.

As for the surface temperature, a special thermometer is used. Always take the steel surface temperature readings at the hottest and coldest points on the structure. These instruments can give false readings if used in direct sunlight.


Sling psychrometer used to determine RH.

A surface temperature thermometer can be magnetically attached to steel or taped to other surfaces.

Digital dew point meter with a surface temperature probe. This instrument can calculate temperature delta.

A coating thickness gauge in use on a painted structural steel component.


8.3 Surface Profile And Cleanliness

The surface to be coated must be clean to the required specifi-cation. If the specifications are not met, surface preparation must be completed or redone so the coating can be applied properly. There should not be a long period of time between completion of surface preparation and commencing coating application.

The surface profile is provided by surface roughening to get an anchor pattern or profile for coating adhesion.

Steel Asphalt

Concrete Stone


8.4 Coating Inspection & Testing

The applicator must inspect all of surface preparation as well as coating application work.

Once the coating is applied and dried, it must be inspected for film thickness, pinholes & other conditions. Coatings that are too thick or thin, or have holidays (pinholes) must be detected and repaired before final curing in order to obtain an effective coating system.

8.4.1 Dry Film Thickness Gauges

These can be classified in two categories:

Non-destructive.

Destructive.

Non-destructive gauges do not destroy the coatings being tested.

Common types of non-destructive gauges are:

Magnetic pull-off.

Magnetic fixed probe.

Eddy current fixed probe.

The non-destructive dry film thickness gauges destroy part of the coating film being measured. Once the measurements are done, touch-up must be done to repair the coating. The most common type of these instruments is the (Tooke gauge), also known as the paint inspection gauge.


8.4.2 Pinhole & Holiday Detection

Holiday testing is done to find pinholes, nicks and other breaks in the coating film. Repairing holidays is important especially for continuous immersions of water, chemicals and oils like tanks.

The testing is done after each application of a coating. There are three types of these detectors:

Low voltage DC holiday detector.

High voltage DC holiday detector.

High voltage AC holiday detector.

The low voltage DC holiday detector is used with coatings up to a D.F.T of 10 mils [ 250 microns ] outside this range a high voltage instrument is used.

Pin-Hole Detectors.


9. Coatings Failure—Causes & Prevention

A coating failure occurs when the coating is no longer provides the protection. Premature coating failure occurs when the coating system deteriorates and the surface corrodes more rapidly than expected.

Coating failure occurs for several reasons including:

Selection of the coating system.

Natural causes and environmental.

Surface preparation.

Application of the coating system.

Design and fabrication.

Holiday Detectors.


9.1 Selection Of Coating System

The improper selection of the coating system is one of the causes of failure.

Selection of coating system may be based on the following:

• Known performance of coatings for similar applications.

• Known chemical composition and physical properties of coating.

• Results of exposure tests on coating.

• Anticipated environmental service conditions.

No coating is resistant to all service conditions, and sometimes coating may be selected for other reasons as appearance.

9.2 Natural Causes And Environmental Conditions

Environment is an important factor affecting the selection of a coating system. Oxygen & water are the corrosive elements, little or no corrosion occur unless both elements are present and in contact with the surface of the structure.

There are another elements may cause damage to the protective coatings:

Sunlight, particularly ultra violet rays.

Wind and wind particles and chemicals.

Biodegradation of fungi and bacteria.

Heat and cold.


The rate of corrosion in industrial atmosphere is usually much greater than that in rural atmosphere.

Coating service life is shortened by the chemical attack of corro-sive gases and liquids. Several considerations should be made in the selection of coating systems:

o Surface type.

o Exposure to liquids and vapors of chemicals.

o Surface temperature changes.

o Rain and chemical surface coating reactions.

o Application costs.

9.3 Surface Preparation

70% of all coating failures are caused by inadequate surface pre-paration.

Another factors include:

Improper specifications.

Poor quality control.

Inadequate inspection.

Inefficient application.

Contaminants including dirt, oil, grease, mill scale and rust must be properly removed.

9.4 Application Of The Coating System

The wrong application method or poor use of the proper applic-ation method can lead to coating failure.

improper mixing, incorrect proportion and incorrect type & quality of thinning may cause coating failure.


9.5 Design And Fabrication

Structural design and fabrication flaws can cause complications in the coating application.

There are many problems include:

Areas inaccessible by brush or spray.

Dissimilar metals in contact.

Sharp edges, angles and weld spatter.

Crevices where water and gases are trapped.

If the beginning of failure in a coating film goes incorrect, it may lead to failure of an entire area.

Inspection regularly and repair is essential.

9.6 Common Types Of Coatings Failure And Prevention

The common coating failures are:

9.6.1 Discontinuities In The Coating

A coating must be continuous to be an effective barrier between the surface and the surrounding environment.

This failure is caused by the following:

• Dry Spray: Where a large part of the solvent evaporates before the coating reaches the surface.

This is prevented by choosing the application method.

• Insufficient thickness Of The Coating Applied.

This is prevented by applying sufficient film thickness.


• Uneven Application: resulting in insufficient thickness, too much thickness and pinholes.

This is prevented by application of many light coats to reach required thickness.

9.6.2 Loss Of Adhesion

It results from incorrect surface preparation or incorrect application methods.

This type of failure include several degrees as:

• Flaking: Which is loosening of small pieces of coating less than 6mm in diameter.

• Scaling: Which is more severe loosening of larger pieces of the coating.

• Peeling: Which is extreme form of failure preceded by cracking.

This failure is caused by many reasons and can be prevented as follows:

Poor Mechanical Bonding: This is prevented by roughening the surface.

Mill Scale Or Rust: This is prevented by correct surface preparation to remove mill scale and rust.

Intercoat Delaminations: This is prevented by selection of compatible coating vehicles.

Under Or Over-Curing Of Undercoat: This is prevented by careful timing for drying between coating layers.

Flaking.

Peeling.


9.6.3 Blistering

This is caused by gases or liquids in or under the coating, which exert pressure stronger than the adhesion or cohesion of the coating so that blisters form followed by breaking.

This is prevented by allowing the coating to dry and by removing all soluble salts from the surface.

9.7 Checking, Alligatoring And Cracking

Checking: is slight breaks in the film that do not penetrate the surface.

Alligatoring: is breaks which are wide and extensive but do not break to the surface.

Cracking: is breaks extending to the surface.

This failure result when stress on the film is greater than the coating elastic limits.

This is prevented by the following:

Avoiding application of too thick coating that dry rapidly on the surface.

Avoiding recoating application before properly dried..

Avoiding incompatible coating system.

Selecting of a coating with reasonable flexibility.

Blistering

Alligatoring

Cracking


9.8 Lifting

This is the softening and expansion of an undercoat film by the solvent of newly applied top coating. This failure occur when the solvent of topcoat soften the under-coat.

This is prevented by careful selection of the solvents, allowing the undercoat to dry and applying a tie coat to prevent undercoat softening.

9.9 Wrinkling

This is the formation of ridges and furrows at the coating surface. It occurs when the surface of the coatings expands more rapidly during drying than the bottom of the coating. As in oil base coatings.

This is prevented by applying coatings at specified dried conditions and specified thickness.

9.10 Chalking

It is the loose powder at or just beneath the surface of the coating. It results from decomposition of the coating vehicle. This is prevented if the vehicles are resistant to decomposition and if the pigments strengthen the coating film as in leafing aluminum pigments. Chalking is caused by UV-light, humidity and weathering.

Sometimes chalking is desirable, since a chalking surface is self-cleaning and it is the best type for recoating.

Chalking

Wrinkling.


9.11 Abrasion

It is caused by impact or rubbing. This is minimized by using a high abrasion resistant coating as polyurethane, by strong adhesion as epoxy and by having high impact resistance as vinyl.

9.12 Dry Spray

It is caused when some coating particles dry before reaching the surface. This occurs in summer with fast-drying coating as vinyl.

This is prevented by adding a small amount of less volatile solvent to the coating.

9.13 Fisheyeing

This type of failure occurs in many types of coatings as epoxies. This failure is caused by water or oil in coating, water or oil on the surface.

This is prevented by filtering spray air & removing water or oil before coating application.

9.14 Lapping

It is occurred when each brush stroke or spray gun pass is visible after the coating has dried. This is happened when coatings containing fast solvents are applied to hot surface in hot climates or results from bad application technique.

This is prevented by adding a small amount of slow solvent and choosing a professional application.

Lapping.


9.15 Blushing

This is a white film, or loss of gloss on the coated surface app-eared shortly after application due to water in the coating film applied during excessive humidity (> 85% R.H.)

This is prevented by adding a small amount of slow solvent and applying coating during favorable weather conditions.

9.16 Under Film Corrosion

Corrosion attacks metal under a coating. There are two types of under film corrosion:

Blotchy corrosion: it is irregular solid areas of corrosion under the coating film.

Fili form corrosion: it is a threadlike line of corrosion under the coating film.

All coatings can be penetrated by water to some extent.

Corrosion begins at these areas. The corrosion will exert a pressure on the coating, if these forces are stronger than adhesion, the coating will lift from the surface. A crack will exist where moisture will accumulate and corrosion occur. This corrosion will proceed in narrow lines under the coating film, wherever the adhesion is weak.


9.17 Failure To Cure

This failure is caused by different reasons as,

Improper mixing.

Application of thick coats.

Application at low temperature.

Use of contaminated equipment.

Use of wrong solvent for thinning.

9.18 Running, Sags & Curtains

These failures may be caused by the following:

Too much thick coat to be applied each time.

Too much thinner to be added.

Bad mixing.

Too low temperature.

Sagging.


10. Hazcom & Safety

There should be the best health & safety in the work in the work place. The occupational safety and health administrations (OSHA) Hazard communication standard provides an outline for safety and health. There are main points of the hazard communication standard including the following:

10.1 Hazardous Material Inventory

All hazardous materials must be inventory at the jobsite.

10.2 Material Safety Data Sheets (MSDS)

All information concerning the hazardous materials must be doc-umented in forms (MSDS).

MSDS forms should list both the trade and official name of the material, manufacturer’s name, type of workers who will handle the material, type of work environment and description of worker protection needs.

Standards require that all labels of all containers of hazardous materials should state name of material, manufacturer’s data, hazard warning, precautions, first aid and clean up procedures.

10.3 Training

Workers must receive hazard communication training. Before any new hazardous material is used, all workers must be trained.

Training includes the following:

• Identifying hazardous materials.

• Explaining the hazards that the material creates.

• Providing all the equipment needed to be used with hazardous materials.


• Training in the use of all equipment.

• Availability of MSDS forms.

10.4 Updating Information

The MSDS forms should be updated when a new hazardous material is to be used, if the working environment changes and when further information about any hazardous materials are gathered. Proper safety equipment should be supplied, workers should be trained to use these equipment correctly.

10.5 Safety

Safety is always important in the work site. Its benefits are good health for the workers and lower operating costs. Accidents cause death, injuries, discomfort, medical expenses and loss of income. Your safety depends on your safe work habits. OSHA develops mandatory safety and health standards, it must be enforced in all work sites and inspected regularly.

10.5.1 Personal Protection

Clothing:

Clothing for painters should protect against hazards from chip removal (abrasive blasting, water blasting, chipping, abrasive wheel, etc.), chemicals (solvents, paints, acids, etc.) and poor environment (dust, fumes, etc.). Clothing should be clean and cover all exposed parts of the body. Clothing should have nothing hanging loose such as ties, cuffs, jewelry, or ripped areas that can get caught on projections and cause falls or accidents.

Gloves are important items of clothing. Different types of gloves protect against different hazards. Wear leather gloves for blasting or rigging cables and lines. Use cloth gloves for general work like paint spraying or rolling. Wear chemical and solvent resistant rubber gloves when working with dangerous liquids or chemicals.


Wear a painter’s cap when working. In industrial and construction areas, wear a hard hat. Use special protection for the ears when required and when you feel you need it. Areas with frequent noise or loud noises can damage your hearing. In such cases, wear ear plugs or earmuffs.

Shoes:

Wear steel toed shoes. This will help keep your toes from being crushed by falling objects. Shoes should have slip-resistant soles to prevent falls on slippery surfaces. Shoes should have a heavy sole and strong arch support.

Eye And Face Protection:

When doing general sanding or paint removal you should wear safety glasses, goggles, or both. For heavier work like abrasive blasting and water blasting, use full-face cover helmets & hoods. Wear face shields and hoods when using chemicals.

Respirators:

Respirators are required when the atmosphere at the jobsite con-tains dust or toxic chemicals (during paint spraying, solvent use, blasting, cleaning, etc.). There are several types of respirators:

Air Purifying Respirators:

1) Disperoid: respirators filter dust particles.

2) Chemical Cartridge: respirators filter fumes through activated carbon cartridges. This makes the fumes harmless. The chemical cartridge-type is commonly known as the “air purifying, negative pressure respirator”.

Supplied Air Respirators:

The supplied air respirators are used in confined areas where there is not enough breathable air. A fresh air blower supplies air through a hose to a hood enclosing the worker’s head, or to a mask tightly sealed around the worker’s face.


Clothing should be clean & cover all exposed parts of the body.

Shoes should have a heavy sole and strong arch support.

Helmets

Goggles or

Glasses

For ear protection:

For eye and face protection:

Hoods

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Different types of gloves protect against different hazards.

Types of respirators:

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Clean Up:

Personal hygiene is important. Clean up thoroughly before eating, drinking, or smoking. This helps preventing the ingestion of toxic materials. Clean up well before leaving the job. This will help keep you from tracking paint and chemicals away from the job site, possibly into your home. Your family will appreciate it. Use a hand cleaner to clean skin. Avoid using paint solvents to clean your skin. Paint solvents can be absorbed through the skin into the body & cause serious illness. Always follow safety instructions provided on the containers of the fluids.

Personnel Actions/Responsibilities:

Protect yourself with the right clothes and safety equipment. You must have proper attitudes about your responsibilities for your-self and others.

• Watch fellow workers, look out for possible accidents situations, and warn them.

• Stay up-to-date on current safety regulations.

• Contribute to safe working conditions.

• Keep clothing and body clean. Show you are a professional by a clean, neat appearance.

Substance Abuse:

Using non-prescription drugs or alcohol during the work period is unprofessional and prohibited by all employers. Using such subs-tances can reduce your ability to work safely & to do a good job. This can cause serious dangers to you and your coworkers. Costly effects of this are injuries to workers and costs involved in fixing poor workmanship. Using drugs and alcohol on the job can cause for termination, suspension, or disciplinary action. Using cont-rolled substances while not at work can result in poor work, leading to disciplinary action. Many employers require drug tests for employees. Currently, it is the contractor’s or company’s right to impose drug testing.


10.5.2 Common Accidents And Injuries

According to the National Safety Council in 1987, work accident costs in the construction industry were nearly 3 billion dollars.

Four of every five injuries to painters result from one or more of the following:

1) Falls from scaffolds and heights.

2) Slips and falls on the same level.

3) Over-exertion.

4) Striking objects and structures or being struck by them.

Falls From Scaffolds: One out of four painting injuries is due to a fall from a height like scaffold or staging. This usually happens when scaffolds are raised or lowered, moved from one place to another, or when painters are climbing or reaching for scaffolds and staging.

To prevent this injuries:

Make sure all scaffolds, ladders and related rigging equipment.

Use the right equipment for the job.

Do not take risks due to laziness or trying to save time.

Do not reach dangerously far from a scaffold or ladder. Instead of reaching dangerously, move scaffolds and ladders. Use all needed support devices with scaffolds. Make sure all support devices are in place and in good working conditions. Do not move scaffolds or ladders with people on them unless the equipment is designed for that purpose.


Slips And Falls:

One out of seven painting injuries comes from slips & falls on the same level. These injuries occur where rubbish, waste, & slippery materials are allowed to remain, or where walkways and working surfaces are uneven.

To prevent such injuries, follow safety rules and:

1) Remove waste and litter to a place provided for them.

2) Fill in holes around the place where you are working.

3) Clean up spilled oil, grease, paint and other materials.

Striking Objects Or Structures Or Being Struck By Them:

One out of four painting injuries results from painters striking objects or being struck by them. This occurs where materials or objects fall or roll, when sudden movements by the workers or equipment are made, when vehicles are moved without warning, or when workers are not paying attention.

To prevent such injuries, follow safety rules and:

• Watch where you are going.

• Keep a clear working space around you.

• Avoid roads or ramps used by vehicles on the job.

• When handling, stacking, or storing materials, make sure they are secure from falling, rolling, or harming any workers.

• Have a proper place for all tools, materials, & equipment. Keep them there when not in use.

Over-exertion:

One out of seven painting injuries results from over-exertion. These injuries usually occur when objects or materials are lifted, pulled, pushed or carried.

To reduce the chance of such injuries, follow safety rules, and:


• Use proper tools.

• Lift safely. If a load seems more than you can easily handle yourself, get help. Keep your back straight & lift by straightening your legs. In team lifting, have one person (and only one person) give the signals so that everyone lifts together at the signal

• Use lines or hoists to raise or lower tools and equipment.

• Use good judgment when moving scaffolds and ladders.

10.5.3 Costly Mistakes

Mistakes can cost a company money through injury to workers, increased insurance cost, profit lost through down time, cost of repairs to damaged equipment, and loss of potential business. Someone else’s carelessness will affect you if your equipment goes down, or if the job shuts down. No job means no paycheck. It is your responsibility to act professionally and to do a good job. Treat equipment with care. Keep it properly cleaned and stored when not in use so it will be ready to use to keep the job going.

10.5.4 Ladder Safety

Falls account for many of serious accidents in the painting trades. Preventing falls when working on ladders is important to every worker. Preventing falls from ladders takes proper knowledge and application of regulations & procedures, & proper safety attitudes. OSHA has created a list of regulations and procedures relating to the safe use of ladders. General safe use of ladders involves:

1) Do not use ladders with broken or missing rungs or steps, broken or split siderails, or other faulty or defective const-ruction. When inspecting metal ladders, check the open end of hollow rungs for corrosion and other damage.

2) Type I (industrial grade) ladders should be used.


3) When ladders are put up for use, the base of the ladder should be ¼ the length of the entire ladder away from the structure it is leaning against. Do not use ladders as plat-forms, runways, or scaffolds.

4) Do not place ladders where other construction work can bump or move them (doorways, passageways, driveways, etc.).

5) The top of the ladder should always extend at least three feet above the structure the ladder is leaning against.

6) Tie, block, or otherwise properly secure portable ladders to prevent them from being bumped, moved, or accidentally knocked over.

7) Do not use portable metal ladders for electrical work or where they may contact electrical conductors.

In addition to OSHA regulations and procedures, the following is a list of generally accepted safety practices:

Never work higher than third rung from the top of a straight ladder.

Do not separate the parts of an extension ladder.

Do not use any step ladder more than 20 feet high.

Do not use the top step of a step ladder.

Never use a step ladder as a straight ladder.

Inspect ladders frequently. Look for, loose steps or rungs, loose screws or bolts, rivets, metal braces and rods, split or broken siderails or rungs, and loose or bent hinge spreaders.

Do not use portable ladder longer than 60 feet.

Equip ladders with non-skid safety feet.

Do not exceed specified maximum work load of any ladder.

Only one person on a ladder, unless the manufacturer states otherwise.


The top of the ladder should always extend at least three feet above the structure the ladder is leaning against.


Always face a ladder when climbing or descending it.

Do not reach too far in any direction while on a ladder.

Before moving a ladder, carefully look for ground & overhead obstructions in your path .

Get help when moving a ladder. If the move is a short distance, walk with the ladder held vertically. If the move is a long distance, shorten the ladder, bring it down and carry it to the new site.

When raising or lowering a ladder, place the base against a wall or firm vertical surface. Then walk forward or backward moving hands from rung to rung. Look where you are going, especially when walking backwards.

Do not paint wooden ladders.

Protect wooden ladders with clear protective coatings so that cracks, splinters, or breaks will be visible.

Keep all ladders level at the base and provide a solid support so they cannot sink into the surface.

Equip all straight and extension ladders with safety shoes, unless special conditions prohibit their use.

Do not splice together short ladders to provide a long section.

Tie ladders at the top when in use. A helper must hold the ladder while it is tied or untied at the top.

When using a ladder over a doorway, rope off the doorway and put up a sign to warn users of the door that the ladder is there.

Use hand lines to raise or lower materials and tools.

Keep both hands free when climbing ladders. Hands should hold the siderails of the ladder, not the rungs, when going up or down.


10.5.5 Rigging And Scaffolding

Know how to use scaffolds correctly. Be familiar with basic safety regulations and practices related to different types of scaffolds. Know OSHA and general safety practices described here. Become familiar with the information from the scaffolding supplier.

A summary of OSHA regulations and procedures for scaffolds would include:

1) The scaffolds should be able to support four times the actual rated or recommended load of the scaffold.

2) Immediately repair or replace any damaged or weakened scaffold. This includes accessories such as braces, brackets, trusses, screw legs, and ladders.

3) Do not put up, move, take down, or alter any scaffold except under the supervision of persons trained in scaffold use.

4) The footing or supports for scaffolds must be able to carry the maximum load. Do not use unstable objects such as barrels, boxes, loose concrete blocks, or bricks to support scaffolds or planks.

5) Install guardrails and toeboards on all open sides and ends of platforms more than ten feet above the ground.

6) Guardrails should be approximately 2 by 4 inches with a mid rail when required. Supports should be no longer than 8 feet each. Toeboards should be a minimum of 4 inches in height.

7) When people will be working or passing under the scaffold, it must have a screen between the toeboard and the guardrail along the entire opening.

8) Overlap all platform planking by a minimum of 12 inches and secure the planking from movement.

9) Provide a ladder or other safe access to the scaffold.



10) OSHA requires that scaffold planks extend a minimum of six inches and a maximum of 12 inches over their end supports.

11) The poles, legs, and uprights of scaffolds should be solid. Securely brace poles, legs, and uprights to prevent swaying and movement.

12) Provide overhead protection for workers on a scaffold ex-posed to overhead hazards.

13) Wire, synthetic, or fiber rope used for scaffold suspension must be able to support at least six times its rated load.

14) Tie & securely brace scaffolding against the building at inter-vals not to exceed 30 feet horizontally and 26 feet vertically.

15) Set scaffolds legs on bases or other foundations that can support the maximum rated load.

16) Properly brace scaffolds by cross bracing, diagonal bracing, or both. Make the scaffold solid, square, and rigid. Make all brace connections secure.

General Scaffolding Safety Practices:

1) Inspect all the scaffolding before each job and at regular intervals during jobs. Replace cracked, broken and deterio-rated parts before the equipment is used.

2) Hoist scaffold parts to the erection personnel.

3) When putting up scaffolding, leave room for hoses, lifelines/ safety ropes, spray and blast equipment, etc.

4) Include the weight of equipment (abrasive, paints, hoses, applicators, etc.) when figuring the weight of a work load on a platform.

5) Never go over the weight limit of a scaffold. No more than 2 persons should work on a stage or scaffold designed for a working load of 500 pounds. No more than 3 persons should work on a scaffold designed for a 750 pound working load.


Include paint, sand, and other materials in the weight of the load on the scaffold.

6) Make sure all equipment meets the safety and load handling capacity for the job.

7) Never overload equipment.

8) Frequently test the suspension systems for swing scaffolds (ropes, cables, hangers, roof hooks, etc.).

9) Do not work with materials you are not qualified to use; learn first, then use. Ask questions.

10) Use shims or adjustable extension legs to make the scaffold level on level ground.

11) Use adjusting screws instead of blocking on uneven ground.

12) Never use ladders or makeshift rigs on top of scaffold to increase the height.

13) Brace suspended scaffolds to prevent swaying.

14) Any scaffold over 125 feet high must be designed and app-roved by a registered professional engineer.

15) Stages, except when necessary to pass through a manhole, should be at least 27 inches wide.

16) Use ladders when climbing a scaffold, not the cross-braces.

17) If a ladder is secured on the outside of the scaffolding, it must extend at least 3 feet above the handrail.

18) Use no ladders more than 20 feet high with scaffolding. If higher reaches are necessary, install an intermediate platform.

19) On large scaffolds (30 feet long or more), attach a second ladder at the opposite end from the first ladder to provide a second exit in case of emergency.

20) Coil ropes properly, and store in dry areas.


21) Cables must be inspected and replaced only by experienced persons. Cables should not be kinked, frayed, cut, have any broken strands, or show any corrosion. Cables must have a consistent diameter (a small spot in the cable indicates a broken inner wire core).

22) Do not work on any slippery platform.

23) Do not work on platform in high wind conditions.

24) Do not paint work platforms. Paint makes the surface more slippery and hides defects and damage.

25) Never ride on a moving scaffold.

26) Do not work on scaffolds covered with ice or snow, or during storms.

27) Use safety belts or body harnesses. Attach safety belts and harnesses to a rope or lifeline by a lanyard. Attach the rope or lifeline to a structure independent of the rigging. The independent structure should reach to ground. Safety ropes should have a safety descent device. Rig safety belts and harnesses so they will not allow a drop of more than 6 feet.

28) Use safety nets when working at heights 25 feet or more above the ground unless other safety measures have been approved and installed by the responsible authority. Install the nets as close to the work as possible, but not more than 25 feet beneath it.

29) Be cautious of the dangers of metal scaffolds near electric power lines.

30) Ask your supervisor or other authority if you are not sure about a scaffold’s ability to the job. Do not take chances.


General Rigging Safety Practices:

1) Always read instructions before use. Make sure equipment is in good operating order. Stay below the rated capacity of rig.

2) Coil ropes properly, and store in dry areas.

3) Wire and fiber ropes must be able to support six times their intended loads.

4) Do not use fiber ropes if an acid solution is in use.

5) Do not use ropes exposed to acid or excessive heat.

6) Check cables before use. Apply twice the rated load and lift about one foot. Note any slippage.

7) Frequently test the suspension systems for swing scaffolds (ropes, cables, hangers, roof hooks, etc.).

8) Cables must be inspected and replaced only by experienced personnel.

9) Replace frayed cables. Cables that show 5% or more of the wires broken or which have excessive wear or corrosion must be replaced.

10) Keep the supporting cables for all suspension scaffolds as straight as possible for their entire length. The operator should keep the cables at right angles to ground if possible.

11) Do not overreach or stretch beyond the rigging sides.

12) Equipment should have free fall safety devices and manual controls in case of power failure. It must not move when is off. In addition to the normal brake, power driven units must have an emergency brake that operates automatically when normal descent speed is exceeded.

13) Service power driven machinery according to manufacturer’s instructions, or more frequently if required.


Rope Grab. Lifelines.

Body Belts.

Lanyards.


Full Body Harnesses.

Rescue System.


14) Never operate a malfunctioning machine.

15) Clear all the obstructions, personnel, and equipment before moving the equipment or extending the boom.

16) When locating cables on jobsites, check nearby power lines for electric service wiring to prevent electrocution. When in doubt, consult the power service company for advice.

17) Use safety belts or body harnesses. Attach safety belts and harnesses to a rope or lifeline by a lanyard. Attach the rope or lifeline to a structure independent of the rigging. The independent structure should reach to ground. Safety ropes should have a safety descent device. Rig safety belts and harnesses to allow a drop of not more than 6 feet.

18) The use of safety nets when working at heights of more than 25 feet may be required unless safety measures have been approved by the responsible party. The nets should be installed as close to the work as possible.

19) Do not work with materials you are not qualified to use. Learn first, then use. Ask questions.

20) The operator should make a visual inspection of equipment before each use.

Any job can be done safely. Know general and site safety rules, use common sense, be alert, take time to do the job right, and keep a proper attitude. Know how to apply proper regulations and procedures. Use good common sense and proper attitudes. This will help you contribute to safe work conditions. Strive to make work safe for yourself and others.


11. Product Selection Guide

Theoretical Coverage Rate Description Product Name

10.4 sq. mt/lit (0.14 kg./m²) for 50 microns D.F.T.

KEMPRIM M is a two pack polyamide cured epoxy primer with an excellent rust inhibiting action which provides the coated steel with an outstanding resistance against corrosion.

* Primers: KEMPRIM M

11.4 sq. mt/lit (0.16 kg./m²) (50 μ) d.f.t

KEMPRIM ZRS is a two packs cold curing zinc rich epoxy primer and is designed as an anti corrosive quick drying weldable primer for various paint systems.

KEMPRIM ZRS

7.5 m²/litre (0.275 kg./m²) for 40 microns D.F.T. Number of coats: 1-2 depending on application.

KEMPRIM ZR-1 is supplied as a one component grey colored primer coating based on zinc and epoxy resins.

KEMPRIM ZR-1



6.4 sq. m./ liter (0.2 kg./m²) for 100 microns d.f.t.

KEMCOAT E 115 is high build, solvent containing polyamide cured epoxy coating. The cured film has excellent adhesion to concrete and metallic substrates with an exceptional glossy appearance.

* Solvent Containing Epoxy Resins : KEMCOAT E 115

3.45 sq m/lit (0.4 kg/m²) for 200 microns d.f.t.

KEMCOAT W is multi purpose water based two components epoxy coating, which cures to form a semi mat, flexible and easy to clean finish. KEMCOAT W combines the economy of water emulsifiable coatings and the durability of epoxy based coatings.

* Water-based Epoxy:

KEMCOAT W



5 sq m/liter (0.3kg/m²) at 200 microns D.F.T

KEMCOAT E43 is a two components, solvent free, non-toxic epoxy coating with out-standing mechanical & chemical properties.

* Solvent-Free Epoxy Resins: KEMCOAT E 43

5 sq. m./liter (0.3kg/m²) at d.f.t. 200 microns

KEMCOAT E81 is a solvent free, two components thixo-tropic epoxy coating with outstanding mechanical & chemical properties.

KEMCOAT E 81

1st step: Epoxy Primer and bonding use as a primer coat 0.2 – 0.3 kg/m2(depending on substrate condition) 2ndstep: KEMCOAT-NOVOLAC (A+B)10.4lkg/m2/mm for 300 micron d.f.t per coat

KEMCOAT-NOVOLAC is a solvent free 2 pack component epoxy novolac coating , for an extremely high strength exceptional chemical resistance , heat resistance epoxy coating for steel and concrete.

* Flexible Epoxy coatings:

KEMCOAT NOVOLAC



KEMPRIM M : 0.15 kgm/m² (D.F.T 125 microns). EPOXY PUTTY: 0.3-0.5 kgm/ m². Epoxy Laminating (KEMCOATE81): 2 kgm/ m² (D.F.T 1250 microns. Glass Mat: (450 gm/ m²): 0.5 kgm/ m². Finish Coat (KEMCOAT E81): 0.3-0.5 kgm/ m² (D.F.T 250 microns).

PROLINE EP is a two component solvent – free epoxy reinforced with glass fiber mat to be used for lining and re-bottoming of storage tanks.

* Epoxy For Re-bottoming:

PROLINE EP

0.5 – 0.6 kg/m² (according to thickness and surface conditions.)

EPOXY PUTTY is a two components SF- epoxy system espe-cially formulated to achieve a high perfor-mance material to work in special condi-tions where other kinds of putties failed.

EPOXY PUTTY



4 m²/liter (0.34 kg./m2) for 175 micron d.f.t. Recommended dry film thickness 350 microns. (2- 3 coats depending on application conditions).

KEMCOAT CTE is a two components, solvent containing epoxy / coal-tar coating system for protecting concrete and metal structures wherever durability of epoxy coatings and economy of coal-tar are required, while the color is of minor importance .

* Coal-Tar Epoxy Resins : KEMCOAT CTE

4 m²/liter (0.34 kg./m2) for 250 micron D.F.T. per coat (recommended paint system 2 – 3 coats).

PROTAR is a two components, solvent free epoxy / coal-tar coating system for protecting concrete and metal structures wherever durability of epoxy coatings and economy of coal-tar are required, while the color is of minor importance .

PROTAR



0.35 Kgm/ m²/coat (D.F.T 200 microns) Recommended number of coats is 2-3 coats.

CERAMIC COAT is a 100% solids, SF-epoxy resin based product, with an essentially closed cell Structure. It has a unique chemical resistance , low thermal conductivity and can be used on surfaces operating up to 200 °C.

* Heat Resistant Coatings : CERAMIC COAT

11.75 m2 /L for 40 micron d.f.t

Two components aliphatic polyurethane used as a top coat with gloss and color retention.

*Polyurethane Finish Top Coat:

PROTHAN TC

0.26lkg/m² (d.f.t 200 microns /coat )

A solvent free , two components isocyanate cured flexible polyurethane resin forming a weatherproof , UV resistant finish coat.

KEMCOAT PU


12. Glossary

* Abrasion Resistance:

Resistance to mechanical wear.

* Adhesive Contact Time Or Recoat Interval:

The period of time within which an adhesive or coating will remain in its tacky condition after completion under specific conditions of temperature and humidity. It is the time available before the adhesion dries that something else can stick to it like fresh concrete or second coating which provides chemical bonding between two layers. * ASTM C-881: American Standard for Testing materials sets for formulated epoxy resin in the following:

(a) GRADE : Denotes the viscosity Grade 1 : low viscosity (up to 2,000 cps) Grade 2 : medium viscosity (2,000-10,000 cps) Grade 3 : non sag grade material (gels)

(b) CLASS : Identifies surface temperature at time of application. Class A : epoxies for use when temperature is below 40°F Class B : epoxies for use between 40°F to 60°F Class C : epoxies for use above 60°F

Class C epoxy can work in a Class B condition, but should not be used in place of class A.

(c) TYPE : Describes basic use of formulated epoxies. Type I : an adhesive for old to old surfaces. Type II : is for bonding new to old concrete. Type III : binder / coating (skid resistance).


* Binder: A system used to mix with aggregate or sand to create a higher strength mortar. Epoxy resin + Hardener is considered as liquid binder. * Blistering: Bubbles in the coating caused usually by applying coating to a surface containing excessive moisture or ingress of water vapors from negative hydrostatic pressures or without proper care to seal the pinholes or applying coating in excessive heat (ambient and substrate temperature). * Boiling Point: A temperature at which a solution starts boiling. Example: boiling point of water is = 100 °C (212 °F). * Capillary Action:

When a tube of very small bore is dipped into a liquid vertically, the level of liquid in it is either raised or lowered. Construction chemical : capillary action in concrete which has a very fine tube like capillary tracts which could cause penetration of liquids (absorption). * Coefficient Of Linear Expansion:

The co-efficient of linear expansion of solid mass is the increase in length per unit length of the solid when its temperature is raised to 1 °C.

Increase in length

Original length x rise in temperature


* Cracks:

Caused in the concrete structure, masonry due to several causes. Thorough investigation is essential to determine cause of crack, nature of crack behavior of crack to select the suitable remedial works. * Cross Linked Polymers:

Two or more chains of polymers are joined together resulting in a tight dimensional structure. Thermosetting polymers are example of highly cross linked polymers. Their structure is so rigid that when heated, they decompose or burn rather than melt. * Crystallization: Liquid epoxy resins tend to crystallize if stored at temperatures below 18°C. The crystallized zones can be re-liquefied by heating to 40°C – 60°C. * Curing Time:

The time which elapses before the casting may be put into service. Only after this period are the mechanical and thermal properties indicated in the Instruction Sheets applicable. The curing time is always longer than the demoulding time. * Delamination:

Detachment of a film or coat or layer from the base substrate. * Density:

Mass per unit volume. D= Volume of the substance

Mass of the substance


Units: kg/m³, gm/cm³, pounds/cubic inch etc. Example: Density of water = 1 = 1 kg yield 1 liter. * Effect Of Temperature:

Increase in ambient temperature, increase the rate of reaction. Decrease in ambient temperature, slows down the rate of re-action. * Efflorescence:

A deposit of water soluble salts on the surface of masonry or plaster caused by the dissolving of salts present in masonry, migration of solution to the surface and deposition of the salts when the water evaporates. * Elasticity:

Whenever a deforming force is applied on a body, its shape or size or both undergo a change i.e., it gets deformed and when the deforming forces removed, the body tends to regain its original shape and size due to the restoring force in it. The property of a body by virtue of which it regains its original shape and size when the deforming force is withdrawn is called elasticity. * Elongation: The degree in which a product will stretch under tension before it breaks. This degree is expressed in a percentage of its original length. * Epoxies:

The Derivation of the petroleum by product (epichlorohydrin and bisphenol A ).


Epoxy resin: A special liquid chemical formulation capable of converting to a solid form when mixed with a curing agent (hardener) generally referred as part A or component A. Hardener : (curing agent) a liquid chemical formulation that reacts with an epoxy resin to convert it to a solid form. Generally referred as reactor, part B or catalyst. * Exothermic Reaction:

A chemical reaction during which heat liberates. Example: epoxy resin + hardener reaction. * Fading:

The loss of color by destruction of coloring matter due to expo-sure to light, heat or other chemicals. * Feather Edge:

A temperature edge which leaves no thickness. * Flash Point:

A temperature at which the vapors emitted from a solution ignites at a source given. 1 – 100 °F = Flammable 101 – 249 °F = Combustible +250 °F = Non-Flammable * Flexural Strength:

The ability of material to withstand bending before reaching the breaking point. Measured in psi, N/mm² units.


* Film Thickness: D.F.T.: Dry film thickness - Thickness of the coating (in mils or microns) after the system reached its curing. W.F.T.: Wet film thickness - Thickness of coating (in mils or microns) when the system is applied at a given spreading rate, in wet condition. * Full Cure:

The time required for the applied system to reach 100% of its rated mechanical, physical properties. Usually expressed in days. * Gel Time:

The time which a resin/hardener system requires to gel, i.e. be-comes viscous to hard. Gel time is always longer than the pot life. * Hardness:

The relative resistance of a material to indentation. In the plastics industry, it is measured on a standard scale known as shore. Shore A hardness = for flexible material, example: 35 soft, 80 hard. Shore D hardness = for rigid material, example: 65 less hardness, 85 hardest. * High Modulus:

High strength material that is rigid. Used specifically where high strength is required. * Honey Combs:

Defect in concrete structure caused due to improper compaction, at the time of placing concrete.


Air voids or pockets in the concrete structure reduces the relative strengths of concrete, becomes porous and poses damages in due course. * Hydrophilic: Mixes with water, water is taken up into the structure (foam/gel) when surrounding water disappears the foam/gel releases water (dehydrates) and shrinks. * Hydrophobic: Chemically reacts with water, utilizing hydrogen from water to make foam. * Impact Resistance: Ability of a material to withstand breaking due to a sharp blow. * Initial Cure / Touch Dry / Gel Time:

The period of time it take a liquid stage formulation to form a gel consistency during the curing process (when touch with finger leaves finger print impression but not stick to finger). * Initial Hardness:

It is a period within which the applied system reaches to its initial hardness (applicator can walk on the system without causing damages). * Low Modulus:

The condition in which a material is slightly flexible. Used where resilience will withstand expansion and contraction, vibration, impact and stress.


* MARTENS test (DIN):

Dimensional stability under thermal stress. * Mil:

One thousand of an inch for the measurement of thickness of a coating. (1 mil = 25 microns) * Modulus:

Denotes value of stress ratio (load divided by area) to the strain (such as elongation) of a material. It is a measure of the relative flexibility and resilience of material. Example: Rubber has low modulus and steel has a high one. Measure in psi, kg/cm², N/mm² units. * Neutralization:

Neutralization is a process in which acid reacts with a base to form their conjugate pairs pH value 7. * pH Value: pH is hydrogen ion concentration in solution. Example: water pH = 7 = H+ ions and OH-ions are in equal. Acidic H+ ions increase in concentration than OH-ions. Alkaline OH- ion concentration increases that H+ ions.

A solution becomes more and more acidic it its pH decreases below 7. It becomes more and more (alkaline) its pH increases above 7.


Strong Weak Weak Strong ⇐ ⇒ ⇐ ⇒ ⇐ ⇒ ⇐ ⇒ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 ⇐ ⇒ ⇐ ⇒ Acidic Alkaline (Basic) * Pigments Coloring Paste:

Coloring additive made of similar material with desired color, used for coloring the systems. * Pin Holes: Surface defects in concrete substrate. Pin holes are evident in concrete structures when form work is removed. These pin holes are caused because of air bubbles accumulated at the form work in plastic stage and cured.

* Polymer:

A broad class of chemicals such as epoxy, polyesters, poly-urethane, acrylics etc. usually made by causing a chemical re-action between two or more basic chemicals called monomers. * Polymer Modified Cements:

Cementitious material consists of Portland cements, graded silica fillers and polymers to improve the workability, performance and properties of system * Polymerization:

The union of two or more smaller molecules of similar or different types. Macro molecules are built up from small molecules called monomers by polymerization reaction.


* Pot Life:

The time within which the mixed resin and hardener components can be applied. Pot life is measured in minutes or hours at a given temperature (from the time of mixing until the mixture can be applied) after completion of pot life, the mixture cannot be applied. The pot life depends on ambient temperature, product temperature, volume and quantity of mixture. * Primer: A thin coat applied on a substrate to improve the adhesion of an application such as an epoxy mortar system or other coatings. * Relative Humidity (RH):

The relative humidity of air at a given temperature is the ratio of mass of water vapor actually present in a certain volume of air to the mass of water vapor required to saturate the same volume of air at the same temperature, multiplied by 100. * Resin Content/Glass Content: The resin and glass content of lamination expressed in percent by weight. * Saponification:

The reaction of an alkaline surface (e.g.: concrete, galvanizing) with oils in the vehicle forming a soap which causes delamination (peeling). * Sealer:

A coat of system or the like, intended to seal pores in a surface.


* Sedimentation:

Undesirable separation of filler, which has higher specific weight, in formulated products. * Segregation & Bleeding:

Defect in the concrete caused at the time of pouring concrete due to improper compaction and form work. Only aggregate visible without proper filling of cement binder. This reduces the relative strength of concrete. * Shear Strength:

The ability of a material to withstand a stress that makes two contacting parts slide upon each other in opposite directions. * Shrinkage:

Decrease in volume on curing or drying. * Solids:

The term solids does not represent the state of material (as in solids, liquids or gases). Solids represents the non-volatile substances in a given liquid (non evaporating material). * Solvent Free – 100% Solids: Liquid system which contains 100% non-volatile organic contents. * Solvented:

Liquid system which contains volatile organic contents to certain percentage.


* Spalls:

Defects occurred in the concrete structure due to several causes mechanical stresses, impacts, vibration, re-bar rusting etc.. * Temperature:

(a) Centigrade or Celsius scale = °C (°F – 32) 5/9

(b) Fahrenheit scale = °F (1.8 x °C ) + 32 * Tensile Strength: The ability of a material to withstand a load under tension (i.e. when being pulled apart). Measured in psi, N/mm² units. * Thixotropic:

Material that are gel like at rest but fluid when agitated. Also the system when applied vertical or overhead do not sag or run-down is known as thixotropic nature. * Viscosity: The property of a liquid by virtue of which it opposes the relative motion between its different layers is known as viscosity. Unit in cps (centi poises) Mpa (mega pascals) or KU (Krebs unit).


Similar in consistency to : Viscosity in centi poise

Water = 1

# 10 mortar oil = 500

Pancake syrup = 2,500

Honey = 10,000

Chocolate syrup = 25,000

Catsup = 50,000

Peanut butter = 250,000

Paste-caulking material = 1,000,000

2000 cps maximum = Low viscosity

2000 – 10,000 cps maximum = Medium viscosity

paste = Gel

* Yellowing: Development of yellow color on the coating due to exposure of UV rays, certain chemicals, acid rain etc..

Yellowing.


13. Full Service Support

Prokem has built an excellent reputation by providing a high level of both technical and commercial support for its clients. This support ranges from its research and development to its technical office and client service office.

Prokem provides the best possible training, technical data sheets, training videos and CDs also it organize seminars, presentations and fairs so as to facilitate transfer of knowledge to clients. Such contribution to the achievement of successful results reflects Prokem’s long-standing dedication to quality assurance.


14. Reference

Protective Coatings And Linings; National Association Of

Corrosion Engineers (NACE).

Steel Structures Painting Council (SSPC).

Painting And Decorating Contractors Of America (PDCA).

Occupational Safety And Health Administration (OSHA).

Construction Maintenance & Repair Magazine.

American University, Cairo (AUC).


This Guide Is Prepared And Reviewed By Prokem Technical Office.

Eng. Ashraf Daghashi

Technical Manager

Alexandria : 33 Safeya Zaghloul St., Down Town, Alexandria.

Tel.: (03) 48 03 320 Fax : (03) 48 03 303

Cairo : 3 El Andalos St., Behind Merryland, Misr El Gadida.

Tel. : (02) 45 49 294 Fax : (02) 45 40 343

Factory : Borg El-Arab El Gadida city, Zone 12, Block 1

E-mail : [email protected]

Web site: www.prokemsc.com

Documents

Industrial Paints & Protective Coatings Guide · 2018. 5. 10. · (vehicles) and solvents. Pigments. are the solid part of coatings and it is responsible for color, cosmetic ability