Microsoft Word C041862e doc Reference number ISO 12944 5 2007(E) © ISO 2007 INTERNATIONAL STANDARD ISO 12944 5 Second edition 2007 09 15 Paints and varnishes — Corrosion protection of steel structures[.]
General
For the protection of steel structures against corrosion many paint systems are widely used
This article provides examples of anticorrosive paint systems categorized by corrosivity levels, highlighting their expected durability in Tables A.1 to A.8 of Annex A These systems are included based on their proven effectiveness, though the list is not exhaustive, and other comparable systems are available in the market.
Emerging technologies are constantly developed, often influenced by government legislation, and should be carefully considered when their performance has been validated This validation can be demonstrated through their proven track record or by testing results that meet at least the standards outlined in ISO 12944-6.
Note 1 clarifies that sections 4.2, 4.3, and 4.4 focus solely on the chemical and physical properties of paints, not their application methods The specified drying and curing temperature limits are approximate guidelines, with expected variations depending on each paint's formulation Understanding these distinctions is essential for proper paint selection and application.
Paints can be broadly classified into solvent-borne, water-borne, and solvent-free categories based on their composition They are initially divided into two main types according to their drying and curing methods, followed by further subdivision by generic type and curing mechanism Understanding these classifications is essential for selecting the right paint for specific applications, ensuring optimal performance and durability.
NOTE 2 The main physical and mechanical properties are summarized in Annex C.
Reversible coatings
The film drying process occurs through solvent evaporation without any change in form, making it reversible This means the dried film can be re-dissolved in the original solvent at any time, ensuring easy reprocessing and reuse.
Examples of binders in this type of coating material are: a) chlorinated rubber (CR); b) vinyl chloride copolymers (also known as PVC); c) acrylic polymers (AY)
The drying time will depend, among other things, on air movement and temperature Drying can take place down to 0 °C, although at low temperatures it is much slower.
Irreversible coatings
The film formation process begins with initial drying through solvent evaporation when a solvent is present, followed by a chemical reaction or coalescence, particularly in water-borne paints This process is irreversible, ensuring that once dried, the film cannot be re-dissolved in the original solvent or, for solvent-free coatings, in a typical solvent used with that type of paint.
4.3.2 Air-drying paints (oxidative curing)
In these paints, the film hardens/forms by evaporation of solvent, followed by reaction of the binder with oxygen from the atmosphere
The drying time will depend, among other things, on the temperature The reaction with oxygen can take place down to 0 °C, although at low temperatures it is much slower
4.3.3 Water-borne paints (single pack)
In this type of paint, the binder is dispersed in water The film hardens by evaporation of water and coalescence of the dispersed binder to form a film
The process is irreversible, i.e this type of coating is not re-dispersible in water after drying
Binders which are typically dispersed in water are:
Drying time is influenced by factors such as air movement, relative humidity, and temperature While drying can occur at temperatures as low as +3°C, the process significantly slows down in colder conditions High humidity levels, particularly those exceeding specified thresholds, further extend drying duration.
80 % RH) also impedes the drying process
In general, this type of paint consists of a base component and a curing agent component The mixture of base and curing agent has a limited pot life (see 3.15)
The paint film dries by evaporation of solvents, if present, and cures by a chemical reaction between the base and the curing agent components
The types given below are commonly in use
NOTE The base component and/or the curing agent component may be pigmented
The binders in the base component are polymers having epoxy groups, which react with suitable curing agents
⎯ epoxy combinations (e.g epoxy hydrocarbon resins);
Formulations can be solvent-borne, water-borne or solvent-free
Epoxy coatings tend to chalk when exposed to sunlight, which can affect their appearance and durability For enhanced color and gloss retention, it is recommended to apply a topcoat such as an aliphatic polyurethane, a suitable physically drying coating, or a waterborne coating These options help protect the epoxy surface from UV-induced chalking and maintain its aesthetic qualities over time.
Polyaminoamines (polyamines), polyaminoamides (polyamides) or adducts of these are most commonly used
Polyamides are more suitable for primers because of their good wetting properties Polyamine-cured coatings are generally more resistant to chemicals
The drying time will depend, amongst other things, on air movement and on the temperature The curing reaction can take place down to + 5 °C, and lower for specialist products
The binders are polymers with free hydroxyl groups which react with suitable isocyanate curing agents
⎯ polyurethane combinations (e.g polyurethane hydrocarbon resins) (PURC)
Aromatic or aliphatic polyisocyanates are most commonly used
Aliphatic-polyisocyanate-cured products (PUR, aliphatic) have excellent gloss-retention and colour-retention properties if combined with a suitable base component
Aromatic-polyisocyanate-cured products (PUR, aromatic) give faster curing but are much less suitable for exterior exposure because they tend to chalk and discolour more rapidly
Drying time is influenced by air movement and temperature, with the curing process occurring even at temperatures as low as 0 °C or below To achieve optimal results and prevent issues like bubbles or pinholes, it is essential to maintain relative humidity within the paint manufacturer's recommended range during curing Proper environmental conditions ensure a smooth, durable coating.
The film dries/forms by solvent evaporation It cures chemically by reacting with moisture from the air
Drying time is influenced by factors such as temperature, air movement, humidity, and film thickness The curing process can occur at temperatures as low as 0 °C or below, as long as the air maintains adequate moisture levels Lower relative humidity levels can slow down the curing process, affecting overall drying efficiency.
Adhering to the paint manufacturer's guidelines on relative humidity and wet and dry film thickness is crucial to prevent coating defects such as bubbles and pinholes Ensuring proper application conditions helps achieve a smooth, durable finish and maintains the integrity of the coating Following these instructions is essential for optimal results and long-lasting protection of the surface.
General properties of different generic types of paint
For comprehensive guidance, refer to Annex C, which serves as an aid to selection When utilizing this annex, it is essential to also consult Tables A.1 to A.8 in Annex A, along with manufacturers’ published data and insights from previous project experiences, to ensure an informed and reliable selection process.
Classification of environments and surfaces to be painted
In accordance with ISO 12944-2, the environment is divided into the following categories:
Three categories for water and soil:
Im1 immersion in fresh water;
Im2 immersion in sea or brackish water;
In new structures, substrates typically include low-alloy steel of rust grades A, B, and C as defined in ISO 8501-1, along with galvanized and metallized steel (see ISO 12944-1) Proper surface preparation for these substrates is outlined in ISO 12944-4, with recommended preparation grades specified in the relevant tables based on corrosivity categories The paint systems listed in Annex A are standard options for protecting steel surfaces with rust grades A to C, or hot-dip galvanized and metallized steel, in environments described by ISO 12944-2 When steel shows advanced deterioration, such as pitting corrosion corresponding to rust grade D, increased dry film thickness or additional coats are necessary to account for surface roughness, and consulting the paint manufacturer is advised for optimal solutions.
In principle, no corrosion protection is required for corrosivity category C1 If, for aesthetic reasons, painting is necessary, a system intended for corrosivity category C2 (with a low durability) may be chosen
Unprotected steelwork intended for corrosivity category C1, when initially transported, stored temporarily, or assembled in an exposed environment such as a C4/C5 coastal area, is susceptible to corrosion caused by airborne salts and contaminants This corrosion process can continue even after the steel is relocated to its final C1 environment To prevent this, steel should be protected during storage through appropriate measures such as applying a suitable primer coat The primer's dry film thickness should be tailored based on the expected storage duration and the severity of the storage environment, ensuring optimal corrosion protection.
Regular maintenance of coated surfaces involves inspecting the existing coating condition using appropriate methods such as ISO 4628-1 to ISO 4628-6 to determine if partial or complete repainting is necessary Based on the assessment, the suitable surface preparation and protective paint system should be specified, with consultation from the paint manufacturer for optimal recommendations Preparing test areas can help verify the manufacturer's guidance and ensure compatibility with the existing paint system, ensuring effective maintenance and longevity of the coating.
Type of primer
Tables A.1 to A.8 in Annex A specify the appropriate primer types for different applications According to ISO 12944, primers are categorized into two main groups based on their pigment content, ensuring optimal corrosion protection and adhesion.
⎯ Zinc-rich primers, Zn (R), are those in which the zinc dust pigment content of the non-volatile portion of the paint is equal to or greater than 80 % by mass
Other miscellaneous primers include those containing zinc phosphate or other anticorrosive pigments, as well as formulations where zinc dust pigment makes up less than 80% by mass of the non-volatile portion of the paint For health and safety reasons, zinc chromate, red lead, and calcium plumbates are not commonly used in primer formulations Refer to Annex B for information on pre-fabrication primers.
The zinc dust pigment shall comply with ISO 3549
NOTE 1 A method for the determination of the zinc dust pigment content of the non-volatile portion of a paint is described in ASTM D 2371
The durability of zinc-rich primers (Zn(R)) is primarily based on the requirement that their dry film contains at least 80% zinc dust by mass This standard is reflected in the tables detailing paint system performance It is important to note that certain countries have established national standards that mandate a zinc dust content in zinc-rich primers exceeding the 80% minimum, ensuring enhanced corrosion protection and long-term durability of these coatings.
Low-VOC paint systems
The examples listed in Annex A include paint systems with a low VOC content designed to meet requirements for low emission of solvents
The article highlights that for each corrosivity category, separate tables specify the availability of paints as water-borne materials and indicate whether they are offered in 1-pack or 2-pack formulations Many of the listed paint systems incorporate either high-solids or water-borne paints for both primer and topcoat layers, often in combinations For additional details regarding VOC content and regulations, refer to Annex D.
Dry film thickness
Definitions of dry film thickness (DFT), nominal dry film thickness (NDFT) and maximum dry film thickness are given in 3.10, 3.11 and 3.12, respectively
The film thicknesses listed in Tables A.1 to A.8 represent nominal dry film thicknesses Dry film thicknesses are typically measured across the entire paint system, but if deemed necessary, the dry film thickness of the primer coat or specific sections of the paint system can be measured separately to ensure precise application.
NOTE Depending on the instrument calibration, measurement method and dry film thickness, the roughness of the steel surface will have a different degree of influence on the measurement result
The thickness of dry films on rough surfaces should be measured according to ISO 19840, while measurements on smooth and galvanized surfaces must adhere to ISO 2808 standards, unless alternative arrangements are mutually agreed upon by involved parties.
Unless otherwise agreed, the following acceptance criteria, as stated in ISO 19840, shall apply:
⎯ the arithmetic mean of all the individual dry film thicknesses shall be equal to or greater than the nominal dry film thickness (NDFT);
⎯ all individual dry film thicknesses shall be equal to or above 80 % of the NDFT;
Individual dry film thicknesses that fall between 80% of the NDFT and the NDFT are acceptable, provided they constitute less than 20% of the total measurements Ensuring most measurements are within the acceptable range maintains coating quality and compliance with standards This guideline helps in assessing the consistency of dry film thickness and supports quality assurance in coating applications.
⎯ all individual dry film thicknesses shall be less than or equal to the specified maximum dry film thickness
To ensure optimal coating quality, it is essential to control dry film thickness and prevent areas of excessive coating buildup The maximum dry film thickness (individual layer) should not exceed three times the nominal dry film thickness When dry film thickness exceeds this limit, expert consensus must be reached between parties to ensure product integrity Certain products or systems may have a critical maximum dry film thickness, as specified in the paint manufacturer’s technical data sheet, which must be adhered to for proper performance and durability.
The coats and nominal dry film thicknesses specified in Annex A are based on airless spray application Using rollers, brushes, or conventional spray equipment typically results in thinner films, requiring additional coats to achieve the same dry film thickness For precise guidance, consult the paint manufacturer.
Durability
Definitions of durability and of durability ranges are given in ISO 12944-1
The durability of a protective paint system depends on several parameters, such as:
⎯ the type of paint system;
⎯ the condition of the substrate before preparation;
⎯ the quality of the surface preparation work;
⎯ the condition of any joints, edges and welds before preparation;
⎯ the standard of the application work;
⎯ the exposure conditions after application
The condition of an existing paint coating can be effectively evaluated using ISO 4628-1 through ISO 4628-6 standards, which assess aspects such as blistering, cracking, and delamination Additionally, the quality of surface preparation work can be measured with ISO 8501-1 and ISO 8501-3, ensuring optimal adhesion and durability of the new coating Implementing these ISO standards is essential for accurate assessment and achieving long-lasting paint performance.
The tables in Annex A assume that the first major maintenance painting is typically required for corrosion protection once the coating reaches Ri 3, as defined in ISO 4628-3 Based on this, durability is categorized into three ranges in ISO 12944: low (L) for 2 to 5 years, medium (M) for 5 to 15 years, and high (H) for more than 15 years.
Durability is a technical factor that assists owners in establishing effective maintenance programs, rather than representing a guaranteed lifespan Guarantee time, on the other hand, is defined by contractual clauses and is not covered under ISO 12944, with no direct link to durability periods Typically, guarantee time is shorter than the overall durability range, emphasizing their distinct roles in product lifecycle management.
Paint systems with a durability of 5 to 15 years are categorized as "medium," highlighting the importance for users to understand the broad range within this classification When developing specifications, it is crucial to consider this wide durability spectrum to ensure the selected paint system meets long-term performance expectations.
Maintenance is often required at more frequent intervals because of fading, chalking, contamination or wear and tear, or for aesthetic or other reasons.
Shop and site application
For optimal paint system performance, it is highly recommended to apply most or all coats in the shop environment Shop application offers significant advantages such as controlled conditions, consistent quality, and improved curing, which enhance the durability and appearance of the finish However, it also has disadvantages including increased transportation costs and logistical challenges Overall, applying the complete paint system in the shop ensures better control over the coating process, resulting in a more durable and high-quality finish.
Using this application method offers significant advantages, including better control of application, controlled temperature and relative humidity, easier repair of damage, higher output, and improved waste and pollution management However, it also presents some disadvantages, such as potential limitations on building size, the risk of damage during handling, transport, and erection, the possibility of exceeding maximum overcoating times, and contamination of the final coat.
After completion of fabrication on site, any damage shall be repaired in accordance with the specification
Repairs on surfaces often leave visible marks, which can affect the overall appearance To ensure a seamless and aesthetically pleasing finish, applying a topcoat over the entire area on-site is highly recommended This approach helps conceal repair marks and provides a uniform, attractive finish.
Site application of the coating system will be strongly influenced by the daily weather conditions, which will also have an influence on the expected lifetime
When preloaded bearing-type connections are to be painted, it is essential to use paint systems that do not cause an unacceptable reduction in the preloading force The choice of paint systems and necessary precautions should be tailored to the specific structure type, as well as considerations for subsequent handling, assembly, and transportation, to ensure maintaining the connection’s integrity.
6 Tables for protective paint systems
Reading the tables
The tables in Annex A provide examples of paint systems tailored for various environments, with shading for clarity The dark-grey shading in the “Expected durability” columns indicates the anticipated lifespan of each system It is essential that all paints used are suitable for the highest levels of corrosion stress relevant to their corrosivity or immersion category The specifier must ensure that proper documentation or manufacturer statements confirm the suitability and durability of the selected paint system for the specific environment When necessary, the durability and suitability should be validated through experience or laboratory tests in accordance with ISO 12944-6 or other accepted standards.
The paint systems are categorized in the tables based on two principles: first, Tables A.1, A.7, and A.8, referred to as the “summary table,” list systems suitable for multiple corrosivity categories, arranged according to the binder used in the topcoat, facilitating system selection based on topcoat performance and enabling comparison of durability when the corrosivity category is uncertain Second, Tables A.2 through A.6, known as “individual tables,” specify systems for a single corrosivity category (grouping C5-I and C5-M as one), organized by the type of priming coat, which is ideal for users with precise knowledge of the environmental corrosivity their structure will face.
This article presents a selection of "typical" paint systems; however, some of these are not universally available or representative across all countries While a comprehensive overview of every possible system is impossible, this listing aims to provide a general understanding of common options.
When selecting a paint system from the provided tables, it is essential for the specifier to determine whether to refer to the summary table or the individual tables, as the system numbering differs between them Proper selection ensures accurate application of the specified paint system and adherence to project requirements Understanding these distinctions streamlines the decision-making process for using the correct paint solutions in various projects.
Parameters influencing durability
Many paint systems have demonstrated durability beyond 15 years, with some achieving proven track records of over 25 years Increasing the total dry film thickness and the number of coats can significantly extend the lifespan of a paint system Additionally, selecting a coating system designed for a higher corrosivity category than the actual environment can enhance durability in lower-corrosivity conditions.
Category C5-I covers, in general terms, the atmospheres that could be encountered at various industrial locations Special care should be taken when writing coating specifications for items of equipment or
During their specified shelf life (see 3.16), paints can be used without their age having any influence on application of the paint or on the performance of the resulting coating.
Designation of the paint systems listed
A paint system is identified by its system number listed in Tables A.1 to A.8 The designation format includes the relevant table number and system number, such as "ISO 12944-5/A2.08," exemplifying how each system is clearly referenced This standardized naming convention ensures precise identification of paint systems across various documentation.
When coats with different binders are applied within the same paint system number, the designation must specify both the binder used in the priming coat(s) and the binder used in subsequent coats This designation should follow a specific format, as illustrated in Table A.2 for paint system No A2.06, to ensure clarity and proper identification of the coating system.
If a paint system does not fall under the categories listed in Tables A.1 to A.8, comprehensive details such as surface preparation methods, generic type, number of coats, and nominal dry film thickness must be provided as specified in the tables Providing complete information ensures clarity and adherence to standards, facilitating proper selection and application of protective coatings Accurate documentation of these parameters is essential for effective coating performance and compliance with industry regulations.
Guidelines for selecting the appropriate paint system
⎯ Determine the corrosivity category of the environment (macroclimate) where the structure will be located (see ISO 12944-2)
⎯ Establish whether special conditions (microclimate) exist which can result in a higher corrosivity category (see ISO 12944-2)
Refer to Annex A for the relevant table, where Tables A.2 to A.5 provide detailed proposals for various generic paint system types tailored to corrosivity categories C2 to C5 Additionally, Table A.1 offers an overview of the contents covered in Tables A.2 to A.5, ensuring comprehensive guidance on suitable coating solutions for different environmental conditions.
⎯ Identify in the table paint systems with the required durability
⎯ Select the optimum one, taking into account the surface preparation method that will be used
⎯ Consult the paint manufacturer in order to confirm the choice and to determine what commercially available paint system(s) correspond to the paint system selected
The paint systems listed in Tables A.1 to A.8 are illustrative examples; alternative systems with equivalent performance are also acceptable When selecting these systems, it is essential to ensure they meet the specified durability requirements during application, as detailed in section 5.5 To enhance readability, every other line has been shaded. -**Sponsor**Need help rewriting your article to be SEO-friendly and coherent? It can be tough making sure everything flows and ranks well With [Article Generation](https://pollinations.ai/redirect-nexad/pQVNeENN), you can instantly create 2,000-word SEO-optimized articles that capture the core meaning of your content and comply with SEO rules Think of it as having a content team that helps you generate high-quality, engaging articles without the usual cost and hassle Plus, you could save over $2,500 a month compared to hiring a writer!
The article details paint systems for low-alloy carbon steel used in various corrosivity categories (C2 to C5-M) Surface preparation involves using Sa 2½ grade rust, specifically from grades A, B, or C, as per ISO 8501-1 standards The coating process includes primer coats followed by subsequent coats, with specific paint systems designated for each corrosivity category The expected durability of these paint systems varies depending on the category, as outlined in section 5.5 and ISO 12944-1 guidelines.
This article provides a comprehensive overview of various system configurations in Table System No., detailing binder types, primer types, number of coats, and corresponding NDF T amplitudes It highlights different combinations such as AK, AY, EP, PUR, ESI, CR, PV C, and Zn(R), specifying their coat counts and NDF T amplitudes ranging from 60 to 320, depending on the system The data emphasizes the versatility of these systems in application, showcasing how different binders and primer types influence coating layers and performance metrics By analyzing these configurations, manufacturers can optimize coating processes for enhanced durability and quality The detailed tabulation serves as a valuable resource for selecting the appropriate system based on specific project requirements and technical standards.
Table A.1 outlines the categories for low-alloy carbon steel preparations, specifying that Sa 2½ (near-white blast cleaning) is only suitable for rust grade A, B, or C according to ISO 8501-1 standards It details the priming coats, subsequent coats, and paint systems used, along with their expected durability levels, ranging from C2 to C5-M, as specified in section 5.5 and ISO 12944-1.
This article provides a comprehensive overview of corresponding systems in tables, detailing binder types, primer numbers, coats, and associated NDF T values It emphasizes the different binder combinations such as EP, PUR, and ES I Zn(R), along with their respective coat counts and thicknesses, highlighting variations like 1, 2, 3-4, and 5 coats The data also includes specific measurements such as A 4.15, A 5I.04, and A 5M.05, illustrating the diverse configurations for different coating processes Additionally, the table outlines the number of components and primer coats for liquid paints, including 1-pack and 2-pack systems, ensuring clarity on product application and compatibility The detailed specifications support optimal selection and application of coatings in industrial or manufacturing settings.
Waterborne binders for topcoats include options like 1-pack and 2-pack formulations, offering versatility for different application needs Common waterborne ingredients are alkyd X, alkyd X with an oxidized rubber base, chlorinated rubber (CR), acrylics, poly(vinyl chloride) (PVC), epoxy, epoxy ester (E P E), polyurethane (both aliphatic and aromatic), and epoxy combinations It is recommended to verify compatibility with the paint manufacturer before application For epoxy primers, using a compatible subsequent coat enhances performance Additionally, the use of zinc-rich primers (Zn(R)) can provide excellent corrosion resistance Dry film thickness (DFT) varies depending on the formulation, with a typical range from 40 to 80 micrometers, provided the zinc-rich primer is suitable for such thicknesses Proper selection of primers and adherence to recommended dry film thickness values ensure optimal corrosion protection and coating durability.
Table A.2 — Paint systems for low-alloy carbon steel for corrosivity category C2
Substrate: Low-alloy carbon steel
Surface preparation: For Sa 2ẵ, from rust grade A, B or C only (see ISO 8501-1)
Priming coat(s) Subsequent coat(s) Paint system
No Binder Type of primer a
NDFT b in àm Low Med High
A2.03 AK Misc 1-2 80 AK, AY, PVC, CR c 2-4 160
A2.05 AY, PVC, CR Misc 1-2 80 AY, PVC, CR c 2-4 160
Binder for priming coat(s) Type Water-borne possible
Binder for subsequent coat(s) Type Water-borne possible
AK = Alkyd 1-pack X AK = Alkyd 1-pack X
CR = Chlorinated rubber 1-pack CR = Chlorinated rubber 1-pack
AY = Acrylic 1-pack X AY = Acrylic 1-pack X
PVC = Poly(vinyl chloride) 1-pack PVC = Poly(vinyl chloride) 1-pack
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
ESI = Ethyl silicate 1- or 2-pack X PUR = Polyurethane, aliphatic 1- or 2-pack X
Polyurethane (PUR) coatings can be aromatic or aliphatic and are available as one- or two-pack systems Zinc-rich primers (Zn (R)), referenced in section 5.2, are essential for corrosion protection, while primers with miscellaneous anticorrosive pigments serve various protective functions Nominal dry film thickness (NDFT), detailed in section 5.4, is a crucial parameter for coating performance, and compatibility with the paint manufacturer is recommended before application For effective adhesion, it is advised to use one of the subsequent coats as a tie coat when applying ESI primers Additionally, zinc-rich primers can be applied at NDFTs ranging from 40 to 80 micrometers, provided the selected primer is suitable for such thicknesses.
Table A.3 — Paint systems for low-alloy carbon steel for corrosivity category C3
Substrate: Low-alloy carbon steel
Surface preparation: For Sa 2ẵ, from rust grade A, B or C only (see ISO 8501-1)
Priming coat(s) Subsequent coat(s) Paint system
No Binder Type of primer a
A3.04 AK Misc 1-2 80 AY, PVC, CR c 3-5 200
A3.05 AY, PVC, CR c Misc 1-2 80 AY, PVC, CR c 2-4 160
A3.06 AY, PVC, CR c Misc 1-2 80 AY, PVC, CR c 3-5 200
A3.11 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 2 160
A3.12 EP, PUR, ESI d Zn (R) 1 60 e AY, PVC, CR c 2-3 160
A3.13 EP, PUR Zn (R) 1 60 e AY, PVC, CR c 3 200
Binder for priming coat(s) Type Water-borne possible
AK = Alkyd 1-pack X AK = Alkyd 1-pack X
CR = Chlorinated rubber 1-pack CR = Chlorinated rubber 1-pack
AY = Acrylic 1-pack X AY = Acrylic 1-pack X
PVC = Poly(vinyl chloride) 1-pack PVC = Poly(vinyl chloride) 1-pack
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
ESI = Ethyl silicate 1- or 2-pack X PUR = Polyurethane, aliphatic 1- or 2-pack X
PUR = Polyurethane, aromatic or aliphatic
Zinc-rich primers, such as the 1- or 2-pack X a Zn, are highlighted in section 5.2, offering effective corrosion protection Primers containing miscellaneous anticorrosive pigments are discussed under the Misc category The Nominal Dry Film Thickness (NDFT) is a vital specification, with details provided in section 5.4, indicating suitable ranges from 40 µm up to 80 µm when compatible with chosen zinc-rich primers It is recommended to verify paint compatibility with the manufacturer before application and to use an ESI primer’s subsequent coat as a tie coat for optimal adhesion and corrosion resistance.
Table A.4 — Paint systems for low-alloy carbon steel for corrosivity category C4
Substrate: Low-alloy carbon steel
Surface preparation: For Sa 2ẵ, from rust grade A, B or C only (see ISO 8501-1)
Priming coat(s) Subsequent coat(s) Paint system
No Binder Type of primer a
A4.02 AK Misc 1-2 80 AY, CR, PVC c 3-5 200
A4.03 AK Misc 1-2 80 AY, CR, PVC c 3-5 240
A4.04 AY, CR, PVC Misc 1-2 80 AY, CR, PVC c 3-5 200
A4.05 AY, CR, PVC Misc 1-2 80 AY, CR, PVC c 3-5 240
A4.06 EP Misc 1-2 160 AY, CR, PVC c 2-3 200
A4.07 EP Misc 1-2 160 AY, CR, PVC c 2-3 280
A4.10 EP, PUR, ESI d Zn (R) 1 60 e AY, CR, PVC c 2-3 160
A4.11 EP, PUR, ESI d Zn (R) 1 60 e AY, CR, PVC c 2-4 200
A4.12 EP, PUR, ESI d Zn (R) 1 60 e AY, CR, PVC c 3-4 240
A4.13 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 2-3 160
A4.14 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 2-3 200
A4.15 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 3-4 240
AK = Alkyd 1-pack X AK = Alkyd 1-pack X
CR = Chlorinated rubber 1-pack CR = Chlorinated rubber 1-pack
AY = Acrylic 1-pack X AY = Acrylic 1-pack X
PVC = Poly(vinyl chloride) 1-pack PVC = Poly(vinyl chloride) 1-pack
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
ESI = Ethyl silicate 1- or 2-pack X PUR = Polyurethane, aliphatic 1- or 2-pack X
PUR = Polyurethane, aromatic or aliphatic
This article provides essential information about zinc-rich primers, including the use of 1- or 2-pack options with nominal dry film thickness (NDFT) guidelines specified in section 5.4 Compatibility between primers and paint products should be verified with the manufacturer to ensure optimal performance For ESI primers, it is recommended to apply at least one subsequent coat as a tie coat to achieve proper adhesion and corrosion protection Additionally, working with an NDFT ranging from 40 µm to 80 µm is possible, provided that the selected zinc-rich primer is suitable for the desired film thickness Primers containing miscellaneous anticorrosive pigments are also available for specialized applications, enhancing the versatility of corrosion protection solutions.
Table A.5 — Paint systems for low-alloy carbon steel for corrosivity categories
Substrate: Low-alloy carbon steel
Surface preparation: For Sa 2ẵ, from rust grade A, B or C only (see ISO 8501-1)
Priming coat(s) Subsequent coat(s) Paint system Expected durability
No Binder Type of primer a
A5I.01 EP, PUR Misc 1-2 120 AY, CR, PVC c 3-4 200
A5I.02 EP, PUR Misc 1 80 EP, PUR 3-4 320
A5I.03 EP, PUR Misc 1 150 EP, PUR 2 300
A5I.04 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 3-4 240
A5I.05 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 3-5 320
A5I.06 EP, PUR, ESI d Zn (R) 1 60 e AY, CR, PVC c 4-5 320
A5M.01 EP, PUR Misc 1 150 EP, PUR 2 300
A5M.02 EP, PUR Misc 1 80 EP, PUR 3-4 320
A5M.04 EP, PUR Misc 1 250 EP, PUR 2 500
A5M.05 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 4 240
A5M.06 EP, PUR, ESI d Zn (R) 1 60 e EP, PUR 4-5 320
A5M.07 EP, PUR, ESI d Zn (R) 1 60 e EPC 3-4 400
Binder for priming coat(s) Type Water-borne possible
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
EPC = Epoxy combination 2-pack EPC = Epoxy combination 2-pack
ESI = Ethyl silicate 1- or 2-pack X PUR = Polyurethane, aliphatic 1- or 2-pack X
PUR = Polyurethane, aromatic or aliphatic
1- or 2-pack X CR = Chlorinated rubber 1-pack
PVC (Poly(vinyl chloride)) comes in 1-pack formulations, while Zinc-rich primers (Zn (R)) are detailed in section 5.2, offering enhanced corrosion protection Miscellaneous primers contain various anticorrosive pigments to suit different applications Nominal dry film thickness (NDFT), discussed further in section 5.4, is a key parameter for optimal coating performance It is recommended to verify compatibility with the paint manufacturer before application For ESI primers, using one of the subsequent coats as a tie coat ensures proper adhesion Additionally, work with an NDFT ranging from 40 µm to 80 µm is feasible if the chosen zinc-rich primer is suitable for that thickness, ensuring effective corrosion resistance.
Table A.6 — Paint systems for low-alloy carbon steel for immersion categories
Substrate: Low-alloy carbon steel
Surface preparation: For Sa 2ẵ, from rust grade A, B or C only (see ISO 8501-1)
Low-durability systems are not recommended and therefore no examples of these are shown
Priming coat(s) Subsequent coat(s) Paint system Expected durability
No Binder Type of primer a
No of coats NDFT b in àm
No of coats NDFT b in àm
A6.04 EP Misc 1 80 EPGF, EP, PUR 3 500
Binder for priming coat(s) Type Water-borne possible f
Binder for subsequent coat(s) Type Water-borne possible f
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
ESI = Ethyl silicate 1- or 2-pack X EPGF = Epoxy glass flake 2-pack
PURC = Polyurethane combination 2-pack PURC = Polyurethane combination 2-pack
PUR = Polyurethane, aromatic or aliphatic
1- or 2-pack X PUR = Polyurethane, aromatic or aliphatic
Zinc-rich primers (X a Zn) are commonly used in corrosion protection, with specific recommendations for application, such as using one of the subsequent coats as a tie coat when working with ESI primers The nominal dry film thickness (NDFT) typically ranges from 40 µm to 80 µm, depending on the zinc-rich primer selected, provided it is suitable for the desired NDFT Primers with miscellaneous types of anticorrosive pigments offer additional protective options, while water-borne products are generally not suitable for immersion environments For detailed application procedures, refer to section 5.2 on primers and section 5.4 for NDFT specifications.
Table A.7 — Paint systems for hot-dip-galvanized steel for corrosivity categories
Substrate: Hot-dip-galvanized steel
ISO 12944-4 gives some examples of surface preparation The type of surface preparation depends on the type of paint system, and should be stated by the paint manufacturer
Priming coat(s) Subsequent coat(s) Paint system Expected durability g
No Binder No of coats
Type of binder No of components
AY = Acrylic 1-pack X AY = Acrylic 1-pack X
PVC = Poly(vinyl chloride) 1-pack PVC = Poly(vinyl chloride) 1-pack
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
PUR = Polyurethane, aromatic or aliphatic
This article explains that 1- or 2-pack X PUR refers to polyurethane coatings, with "b NDFT" indicating the nominal dry film thickness, as detailed in section 5.4 The durability of these coatings primarily depends on their adhesion to hot-dip galvanized substrates, ensuring long-lasting protection and performance.
Table A.8 — Paint systems for thermally sprayed metal surfacesfor corrosivity categories
Substrate: Thermally sprayed metal (zinc, zinc/aluminium alloys and aluminium)
Surface preparation: See ISO 12944-4:1998, Clause 13
It is recommended that sealing or application of the first coat of the paint system be carried out within 4 h
If used, sealers should be compatible with the subsequent paint system
No Binder No of coats
A8.01 EP, PUR 1 NA h EP, PUR 2 160
A8.02 EP, PUR 1 NA h EP, PUR 3 240
A8.04 EP, PUR 1 NA h EP, EPC 3 320
Type of binder No of components
EP = Epoxy 2-pack X EP = Epoxy 2-pack X
EPC = Epoxy combination 2-pack EPC = Epoxy combination 2-pack
Polyurethane (PUR) coatings are available in aromatic 1- or 2-pack options, while aliphatic PUR coatings also come in similar packaging types, offering durability and color stability Nominal dry film thickness (NDFT) is a key specification, with further details available in section 5.4; it's important to note that water-borne products are generally not suitable for immersion applications The durability of the coating system in some cases depends on the adhesion of the paint to the thermally sprayed substrate, rather than the coating thickness itself Additionally, the dry film thickness of the sealer coat is typically not significant to the overall system thickness, as indicated by "NA" (not applicable) in certain contexts.
Pre-fabrication primers are applied as thin films to freshly blast-cleaned steel to provide temporary corrosion protection during fabrication, transportation, erection, and storage These primers are then overcoated with a final paint system, often including an additional priming coat Compatibility between various types of pre-fabrication primers and different paint systems is documented in Table B.1, while their suitability under different exposure conditions with related paint systems is detailed in Table B.2.