Paint & Coating

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramcosemployees. Any material contained in this document which is notalready in the public domain may not be copied, reproduced, sold, given,or disclosed to third parties, or otherwise used in whole, or in part,without the written permission of the Vice President, EngineeringServices, Saudi Aramco.

Chapter : Materials And Corrosion Control For additional information on this subject, contactFile Reference: COE10104 O.S. Abdul Hamid on 874-2532 or A.M. Al-Ghamdi on 873-1290

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Paint And Coating Systems

Engineering Encyclopedia Materials And Corrosion Control


Saudi Aramco DeskTop Standards

CONTENTS PAGES

INFORMATION

Paint and Coating Systems 1

Paint and Coating Terms 3

Selecting Paint and Coating Systems for Onshore Applications 10

Structures and Facilities 10

Steel Pipelines and Piping 13

Selecting Paint and Coating Systems for Offshore Applications 16

WORK AID 20

Work Aid 1: Guidelines and Standards for Selecting Paint andCoating Systems for Onshore Applications 20

Work Aid 2: Guidelines and Standards for Selecting Paint andCoating Systems for Offshore Applications 41

GLOSSARY 53



Saudi Aramco DeskTop Standards 1

PAINT AND COATING SYSTEMS

Paint and coating systems are the most widely used method for corrosion control. Eachcoating system is selected to provide a barrier between a structure and a particular corrosiveenvironment. Corrosive environments for structures can range from mild atmosphericexposure to immersion in highly corrosive solutions. Coatings are applied as liquids to thesurface of a material. Afterwards, they dry or react chemically to form a solid covering overthe material. Coatings protect structures by the following mechanisms:

Impermeability - prevents or limits water migration from the environment tothe surface of the coated structure.

Inhibition - releases inhibitors into the moisture that reaches the structuresurface.

Cathodic protection - corrosion of exposed primer produces an electric currentthat protects the underlying metal structure.




Coating components are classified as pigments, binders, and solvents (Figure 1). Pigmentsmainly provide color and hide the underlying surface. Non-volatiles, or binders, bind thepigment particles together and join the entire coating system to the structure surface.Volatiles, or solvents, are added to dissolve the binder so they are easier to apply. These paintand coating terms are explained in greater detail in the following section. The importance ofsurface preparation is discussed after the paint and coating terms.

aa

Non-volatiles(Binders)

Pigments

Volatiles(Solvents)

1. Active2. Diluent3. Latent

1. Resins and oils2. Additives Anti-foam agents Anti-skin agents Bactericides Catalysts Driers Flow control agents

1. Hiding2. Extending3. Additives Bodying agents Fire retardants Inhibitors

Fungicides Plasticers Solvent release agents Stabilizers Wetting agents

Latent driers Stabilizers

V

E

H

I

C

L

EFinalPaintFilm SO

LIDS

Components of Liquid CoatingsFigure 1




Paint and Coating Terms

Substrate

The structure surface to be coated is called the substrate. The substrate must be prepared so itwill provide the optimum foundation for the coating system. In the petroleum industry, hot-rolled carbon steel is the most common substrate over which coatings are applied. If thesurface of hot-rolled steel is properly prepared, it has one of the best surfaces for coatingsapplication.

Anchor Pattern

Most high-performance coatings require a clean, rough surface to obtain good mechanicaladhesion to a metal surface. The anchor pattern is a measure of the profile formed by thehills and valleys of the substrate (Figure 2). Most high-performance coatings obtain goodadhesion with anchor patterns that have a depth of 25 to 50 micrometers (mm). This depth isequivalent to 1 to 2 mils, or 1/1000 to 2/1000 of an inch. For high-performance coatings, theanchor pattern is usually obtained by abrasive blasting the metal surface.

a

Anchor Pattern of a Material SurfaceFigure 2

Binder

A binder is a liquid in the paint that is converted a dense, tight film when the paint dries. Abinder's ability to form such a film is related to its molecular structure and complexity. Thereare many different types of binders (e.g., epoxies, vinyls, alkyds, and polyurethanes). Theyare generally classified according to the chemical reactions they undergo as the coating driesor cures. Binder molecules are also called resins. The functions of binders are as follows:

Bind pigments together. Adhere to the substrate. Provide flexibility to the coating film. Increase abrasion resistance.




Promote chemical and atmospheric resistance.




Pigments

Pigments are solid particles that are included within coating formulations. Several differentpigments may be used in the same coating to contribute to its characteristics. Pigmentsperform the following functions:

Produce color that decorates or hides the substrate.

Protect binders from solar radiation.

Inhibit corrosion.

Increase chemical and corrosion resistance.

Reinforce hardness, cohesive strength, toughness, and/or tensile strength.

Increase abrasion resistance.

Prevent sagging of a wet coating film.

Provide better coverage of the substrate.

Improve coating adhesion.

Vehicle

The vehicle is the liquid portion of a paint and anything dissolved in it. Most paints containvarying amounts of solvents, or volatiles, that make them easier to apply. Paints also containnon-volatile binders (e.g., resins, oils, and additives).

Volatiles

Volatiles or solvents are added to keep the binder in solution during storage and application ofthe paint. Numerous organic solvents are used including aromatic hydrocarbons, alcohols,ethers, and esters. Water is often used as the solvent in latex paints. Most coatings are madewith multiple solvents.




Wet Film Thickness

Theoretically, one liter of paint should cover 1000 m2 of surface area to a depth of 1 mm, or40 m2 of surface area to a depth of 25 mm. This coverage assumes that the surface isperfectly flat and that no paint is lost as it is applied to the substrate. (Figure 3).

a

Wet and Dry Film ThicknessFigure 3

Dry Film Thickness

Volatiles leave or evaporate from the coating material after it is applied. When volatilesevaporate, the dry film becomes thinner than the wet film thickness (WFT) (Figure 3). Forexample, assume that one liter of a particular paint contains 50% solids and 50% solvents byvolume. If the liter of paint is spread 25 mm thick, it will cover 1000 m2; however, half of thevolume consists of volatiles. When the volatiles evaporate, the dry film thickness (DFT) canbe calculated as follows:

DFT = WFT x % solids

= 25 mm x 50% = 12.5 mm

The preceding equation does not take paint thinners into consideration. If a thinner is usedwhen a paint is applied, the dry film thickness is calculated as follows:

DFT = WFT %solids by volume

(1 + %thinner by volume)

For example, the dry film thickness of a paint that has a wet film thickness of 100 mm, a non-volatile volume of 40%, and contains 10% thinner, is calculated as follows:

DFT = 100mm 0.40

(1 + 0.10) = 36.4 mm




Coverage

Manufacturers give theoretical coverage for paints with the assumption that they are used onflat, smooth surfaces. The actual coverage is much less than the theoretical coverage becausereal surfaces are irregular, and because some paint is always lost during application.Normally, up to 20% of paint can be lost. Irregular surfaces such as heavily pitted steel andrough concrete require more paint than relatively smooth surfaces.

The theoretical coverage of paint can be calculated as follows:

Coverage(m2) = liters of coating %solids as decimal 1000

DFT(mm)or,

Coverage(ft2) = gallons of coating %solids as decimal 1604

DFT(mils)

If, for example, a dry film thickness of 60 mm is needed from one liter of paint that contains40% solids, the theoretical coverage is calculated as follows:

Coverage = 1L 0.40 100060mm

= 6.67 m2

Adhesion

Adhesion is a measure of the strength of the bond that develops between the coating systemand the substrate. Adhesion of a coating to its substrate is critical to the long-termperformance of the coating. Generally, the stronger the adhesive bond formed between thecoating and the substrate, the longer the coating will be held to the structure surface. Coatingsmay form three types of adhesion bonds with substrateschemical, polar, and mechanical.

The strongest and most effective adhesive bond is the chemical bond. It is created by achemical reaction between the coating binder and the substrate. Inorganic zinc and epoxyprimers are examples of coatings that form a chemical bond with steel. Chemical bonding issometimes called primary valence bonding.

Polar adhesion is caused by the polar attractions between the resin molecules in the paint andthe metal substrate. Polar adhesion is much more common than chemical adhesion. In polaradhesion, positive and negative-charged portions of the resin molecule are attracted tooppositely charged areas on the substrate. Polar adhesion is sometimes called secondaryvalence bonding.




Mechanical adhesion is associated with surface roughness or anchor pattern. The hills andvalleys of the substrate increase the adhesion by increasing the surface roughness andeffective surface area.




Primer Coat

The primer is the first coating that is applied to a material or substrate (Figure 4). The primermust have strong adhesion to the substrate and provide proper adhesion for the intermediatecoat. Primers should resist chemical attack and be compatible with the rest of the coatingsystem. Primers are sometimes applied days or months before additional coatings are applied.Therefore, they must resist corrosion as a single coat until the other coatings are applied.

Intermediate Coat

The main purpose of an intermediate coat is to add thickness to the coating system (Figure 4).Physical thickness helps the coating system to (1) resist chemical attack, (2) reduce themoisture vapor transfer rate, and (3) increase resistance to electricity, impact, and abrasion.The intermediate coat must also adhere strongly to the primer and topcoat.

Topcoat

The topcoat is the first defense against corrosive elements in the environment (Figure 4). Thetopcoat is usually more dense, but not as thick, as the intermediate coat. It must bond to theintermediate coat and provide long term protection to the base coats. The topcoat oftenprovides color, texture, and gloss to the paint.

a

Basic Components of Coating SystemsFigure 4




Surface Preparation

The main goal of surface preparation is to remove contaminants that cover adhesion sites onthe substrate. Contaminants include dirt, dust, oxide films, mill scale, oil, and moisture.Saudi Aramco uses several surface preparation techniques. These techniques include solventcleaning, hand and power tool cleaning, and abrasive blast cleaning.

Solvent Cleaning - Solvent cleaning is intended to remove oils and grease that prevent adhesionbetween the coating and the substrate. Solvent cleaning does not remove, oxide films, scales,or most old coatings from the substrate. Cleaning solvents include cleaning emulsions,cleaning compounds, and steam cleaning.

Hand and Power Tool Cleaning - Hand and power tool cleaning are intended to remove onlyloose scale, loose rust, and loose paint from metal surfaces. Hand tool cleaning includes handbrushing, hand sanding, hand scraping, hand chipping, and other hand impact tools. Handtool cleaning is normally used on small repair jobs or when power-operated equipment is notavailable. Power tool cleaning includes power wire brushes, power impact tools, powergrinders, and power sanders. The least effective power cleaning tool is the power wire brush.It tends to spread contamination over the surface and polish the surface of scale and rustrather than remove them.




Abrasive Blast Cleaning - Abrasive blasting cleans the metal surface and increases the surfaceroughness and anchor pattern of the substrate (Figure 5). This increases the chances forprimary and secondary valence bonding by increasing the effective surface area of thesubstrate (Figure 6). It is important to select the proper abrasive because it affects the anchorpattern. The optimum anchor pattern and degree of surface preparation will be different foreach paint or coating system. Saudi Aramco specifications clearly give the surfacepreparation required for each type of coating.

aa

Blasting Cleans the Metal SurfaceFigure 5

aa

Blasting Roughens the Surface and Increases the Effective Surface AreaFigure 6




SELECTING PAINT AND COATING SYSTEMS FOR ONSHORE APPLICATIONS

Structures and Facilities

Saudi Aramco Engineering Standard SAES-H-001, Selection Requirements for IndustrialCoatings, covers the minimum coatings selection for onshore structures and facilities. Theselection requirements are found in Chapter 5 of SAES-H-001 as follows:

5 SELECTION REQUIREMENTS FOR ONSHORE STRUCTURES AND FACILITIES5.1 Tanks5.2 Vessels5.3 Plant Structures and Equipment5.4 Miscellaneous

Assume that a coating is needed for the interior of a new desalter vessel. First, the coatingrequirement for a desalter is located in Section 5.2 Vessels of SAES-H-001 (Figure 7). Thefirst column in Figure 7 shows the categories of equipment to be coated. The second andthird columns show the proper coating systems for new construction and maintenanceapplications, respectively. The coating systems identified in these columns are described inSaudi Aramco Engineering Standard SAES-H-101. SAES-H-101 specifies various approvedSaudi Aramco Paints and Coatings Systems (SAPCS). The last column in Figure 7 includesadditional remarks about application of the coating.




SAES-H-001, Selection Requirements For Industrial CoatingsFigure 7




Structures and Facilities, Contd

Next, the appropriate SAPCS is located in SAES-H-101. According to the table in Figure 7,SAPCS-3 or SAPCS-2A can be used. SAPCS-3 is shown in Figure 8.

SAPCS-3 from SAES-H-101, Saudi Aramco Paint and Coating SystemsFigure 8




Structures and Facilities, Contd

The GENERAL DATA section in SAPCS-3 (Figure 8) includes the maximum servicecondition limitations (Section 2.2) and purchase specifications (Section 2.3) for each coatingsystem. In addition to general information, the SAPCS gives surface preparation and dry filmthickness requirements (Sections 3 and 4). Surface preparation is a critical part of theapplication process. The substrate must be properly cleaned and have a good profile foradequate adhesion. The following abbreviations are used in SURFACE PREPARATIONREQUIREMENTS (Section 3 in Figure 8).

SSPC-SP1 - Solvent cleaningSt 2 - Thorough scraping and wire brushingSt 3 - Very thorough scraping and wire brushingSa1 - Light blast cleaning (brush blast)Sa2 - Thorough blast cleaning (commercial blast)Sa2 1/2 - Very thorough blast cleaning (near white metal blast)Sa3 - Blast cleaning to pure metal (white metal blast)

The SURFACE PREPARATION REQUIREMENTS section often refers to SAES-H-100.SAES-H-100 covers the requirements for corrosion protection of industrial facilities inonshore, offshore, atmospheric, and immersion services.

Steel Pipelines and Piping

Saudi Aramco Engineering Standard SAES-H-002, Internal and External Coatings for SteelPipelines and Piping, gives the mandatory coating selection requirements and coatingsperformance requirements for steel pipelines and other piping. The selection requirements inSAES-H-002 are divided into the following categories.

5 SELECTION REQUIREMENTS5.1 General Requirements for External Coatings5.2 General Requirements for Internal Coatings5.3 Internal Coatings, Various Services5.4 External Pipe Coatings, Cross-Country5.6 External Pipe Coatings, In-Plant

6 DESCRIPTION AND USES OF SPECIFIC ARAMCO PIPE COATING SYSTEMS




Assume that a coating is needed to internally coat production tubing. First, acceptableinternal coatings are located in Section 5.3.2 of SAES-H-002 (Figure 9). The first columnshows the categories of equipment to be coated. The second and third columns show theproper coating systems for new construction and maintenance applications, respectively. Theinformation in these columns refers to approved SAPCSs, which are included in SAES-H-002. The last column includes additional remarks about application of the coating.

SAES-H-002, Internal and External Coatings for Steel Pipelines and PipingFigure 9




Steel Pipelines and Piping, Contd

All acceptable SAPCSs are included in SAES-H-002. According to Section 5.3.2 of SAES-H-002, SAPCS-100 (Figure 10) may be used to internally coat production tubing.

SAPCS-100, Shop-Applied Baked Phenolic or Phenolic EpoxyFigure 10

The GENERAL DATA section (Section II) in SAPCS-100 includes the recommendedoperating conditions and purchase specifications. Section III of SAPCS-100 gives surfacepreparation requirements.

Work Aid 1 contains guidelines and appropriate sections of the Saudi Aramco EngineeringStandards that are needed to select paints and coatings systems for the onshore structuresdescribed in Exercise 2. The complete Saudi Aramco Engineering Standards for paint andcoating systems may be accessed on the Saudi Aramco mainframe computer system.




SELECTING PAINT AND COATING SYSTEMS FOR OFFSHORE APPLICATIONS

The coatings selection requirements for offshore structures and facilities are found in Chapter6 of Saudi Aramco Engineering Standard SAES-H-001, Selection Requirements for IndustrialCoatings as follows:

6 SELECTION REQUIREMENTS FOR OFFSHORE STRUCTURES AND FACILITIES6.1 Structural Steel6.2 Tanks, Vessels and Equipment6.3 Accessories6.4 SPM Buoys

Assume that the coating needs to be repaired on a structural steel member located in thesplash zone of an offshore platform. First, the coating requirement for structural steel islocated in Section 6.1 of SAES-H-001 (Figure 11). The first column shows the categories ofequipment to be coated. The second and third columns show the proper coating systems fornew construction and maintenance applications, respectively. The information in thesecolumns refers to Saudi Aramco Engineering Standard SAES-H-101. Saudi Aramco Paint andCoatings Systems. SAES-H-101 specifies various approved Saudi Aramco paint and coatingsystems. The last column includes additional remarks about application of the coating.




SELECTING PAINT AND COATING SYSTEMS FOR OFFSHOREAPPLICATIONS, Contd

Aramco Standard SAES-H-001, Selection Requirements For Industrial CoatingsFigure 11





Next, the appropriate SAPCS is located in SAES-H-101. According to the table in Figure 11,SAPCS-19B should be used. Figure 12 shows SAPCS-19B.

SAPCS-19B, from SAES-H-101, Saudi Aramco Paint and Coating SystemsFigure 12





The GENERAL DATA section in SAPCS-19B includes the service condition limitations(Section 2.2) and purchase specifications (Section 2.3) for each coating system. In addition togeneral information, the SAPCS gives surface preparation and dry film thicknessrequirements (Sections 3 and 4). Surface preparation is a critical part of the applicationprocess. The substrate must be properly cleaned and have a good profile for adequateadhesion. The following abbreviations are used in SURFACE PREPARATIONREQUIREMENTS (Section 3).

SSPC-SP1 - Solvent cleaningSt 2 - Thorough scraping and wire brushingSt 3 - Very thorough scraping and wire brushingSa1 - Light blast cleaning (brush blast)Sa2 - Thorough blast cleaning (commercial blast)Sa2 1/2 - Very thorough blast cleaning (near white metal blast)Sa3 - Blast cleaning to pure metal (white metal blast)

The SURFACE PREPARATION REQUIREMENTS section often refers to SAES-H-100.SAES-H-100 covers the requirements for corrosion protection of industrial facilities inonshore, offshore, atmospheric, and immersion services.

Work Aid 2 contains guidelines and appropriate sections of the Saudi Aramco EngineeringStandards that are needed to select paints and coatings systems for the offshore structuredescribed in Exercise 3. The complete Saudi Aramco Engineering Standards for paint andcoating systems may be accessed on the Saudi Aramco mainframe computer system.




WORK AID 1: GUIDELINES AND STANDARDS FOR SELECTING PAINT ANDCOATING SYSTEMS FOR ONSHORE APPLICATIONS

Work Aid 1B contains applicable sections of SAES-H-001, Selection Requirements forIndustrial Coatings. Work Aid 1C contains applicable sections of SAES-H-101, SaudiAramco Paint and Coating Systems. Work 1D contains applicable sections of SAES-H-002,Internal and External Coatings for Steel Pipelines and Piping.

Work Aid 1A: Guidelines


1. Determine the type of surface to be coated and the environment to which it will beexposed.

2. Locate the proper equipment description in SAES-H-001 (Work Aid 1B).3. Locate the proper Saudi Aramco paint and coating system (SAPCS) number based on the

applicationnew construction or maintenance.4. Locate the SAPCS number(s) in SAES-H-101 (Work Aid 1C).

Steel Pipelines and Piping


2. Locate the proper equipment description in SAES-H-002, Internal and External Coatingsfor Steel Pipelines and Piping (Work Aid 1D).

3. Locate the proper SAPCS number based on the applicationnew construction ormaintenance.

4. Locate the SAPCS number in SAES-H-002, Aramco Paint and Coating Systems.




Work Aid 1B: SAES-H-001, Selection Requirements for Industrial Coatings

Saudi Aramco Engineering Standard SAES-H-001 covers minimum selection requirementsfor onshore industrial structures and facilities.

Figure 13




Work Aid 1B: SAES-H-001, Selection Requirements for Industrial Coatings, Contd

Figure 14





Figure 15





Figure 16





Figure 17





Figure 18




Work Aid 1C: SAES-H-101, Saudi Aramco Paint and Coatings Systems

Saudi Aramco Engineering Standard SAES-H-101, Saudi Aramco Paint and CoatingsSystems describes various approved SAPCSs specified in other Saudi Aramco EngineeringStandards.

Figure 19




Work Aid 1C: SAES-H-101, Saudi Aramco Paint and Coatings Systems, Contd

Figure 20





Figure 21




Work Aid 1D: SAES-H-002, Internal and External Coatings for Steel Pipelines andPiping

Saudi Aramco Engineering Standard SAES-H-002 gives the mandatory internal and externalcoating selection requirements and mandatory coatings performance requirements for steelpipelines and piping.




Figure 22




Work Aid 1D: SAES-H-002, Internal and External Coatings for Steel Pipelinesand Piping, Contd

Figure 23





Figure 24





Figure 25





Figure 26





Figure 27





Figure 28





Figure 29





Figure 30





Figure 31





Figure 32




WORK AID 2: GUIDELINES AND STANDARDS FOR SELECTING PAINT ANDCOATING SYSTEMS FOR OFFSHORE APPLICATIONS

Work Aid 2B contains applicable sections of SAES-H-001, Selection Requirements forIndustrial Coatings. Work Aid 2C contains applicable sections of SAES-H-101, SaudiAramco Paint and Coating Systems.

Work Aid 2A: Guidelines



2. Locate the proper equipment description in Section 6 of SAES-H-001 (Work Aid 2B).3. Locate the proper Saudi Aramco paints and coatings system (SAPCS) number based on

the applicationnew construction or maintenance .4. Locate the SAPCS number in SAES-H-101 (Work Aid 2C).




Work Aid 2B: SAES-H-001, Selection Requirements for Industrial Coatings

Saudi Aramco Engineering Standard SAES-H-001 covers minimum selection requirementsfor offshore industrial structures and facilities.

Figure 33





Figure 34





Figure 35





Figure 36




Work Aid 2C: SAES-H-101, Saudi Aramco Paint and Coatings Systems

Figure 37





Figure 38





Figure 39





Figure 40





Figure 41





Figure 42





Figure 43




GLOSSARY

brush blast A light abrasive cleaning which results in a surface free of oil,grease, dirt, loose rust scale, loose mill scale, and loose paint.Tightly adhering mill scale, rust, or coating are allowed toremain if they have been exposed to the abrasive blast.Equivalent to Sa1 surface preparation.

commercial blast Abrasive cleaning which results in a surface from which all oil,grease, dirt, rust, scale and foreign matter have beencompletely removed. All rust, mill scale, and old coating mustbe removed except for slight streaks or discolorations.Equivalent to Sa2 surface finish.

near white metal blast Abrasive cleaning which results in a surface from which all oil,grease, dirt, mill scale, rust, corrosion products, oxides, paint,or other foreign matter have been removed. Light streaks ordiscolorations covering no more than 5% of the surface areaare allowed. Equivalent to Sa2-1/2 finish.

primary valence bonding Adhesive bonding of a coating to a structure resulting fromchemical bonds formed by a chemical reaction between thecoating and the substrate.

secondary valence bonding Adhesive bonding of a coating to a structure resulting from thepolar attraction between components in the coating resin andthe substrate.

white metal blast Abrasive cleaning which results in surface with a gray-white(uniform metallic) color, slightly roughened to form a suitableanchor pattern for coating. The surface is free of all oil,grease, dirt, mill scale, rust, corrosion products, oxides, paintand other foreign matter. Equivalent to Sa3 surface finish.

Paint & Coating

Documents

Transcript of Paint & Coating