ISO 8504-3-318 “Preparation of steel substrates before application of paints and related products – Surface treatment methods – Part 3: Cleaning by hand and power tools”

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This document is prepared by Technical Committee ISO/TC 35, Paints and Varnishes, Subcommittee SC 12, Preparing steel substrates prior to application of paints and related products.

The second edition cancelled and replaced the first edition (ISO 8504-3:1993), which had been technically revised.

The main changes from the previous edition are as follows:

— Add rotary impact tools to power tool types;

— Use assessment instead of inspection in article 6.

A list of all the parts in the ISO 8504 series can be found on the ISO website.

Any feedback or questions about this document should be directed to the user’s national standards body. A complete list of these institutions can be found at

ISO 8504-3-318 “Preparation of steel substrates before application of paints and related products – Surface treatment methods – Part 3: Cleaning by hand and power tools”

The properties of protective coatings applied to steel and related products are significantly affected by the state of the steel surface before coating. The main factors known to affect this performance include:

a) There is corrosion and mill scale;

b) The presence of surface contaminants, including salt, dust, oil and grease;

c) Surface profile.

ISO 8501 and ISO 8502 are ready to provide methods for assessing these factors, while ISO 8504 provides guidance on preparation methods that can be used to clean steel substrates, indicating the ability of each method to achieve specified levels of cleanliness.

These international standards do not contain recommendations for protective coating systems applied to steel surfaces. They also do not contain recommendations on surface quality requirements for specific cases, even though surface quality can directly influence the choice of protective coating to be applied and its properties. These recommendations are found in other documents such as national standards and codes of practice. Users of these international standards should ensure that the stipulated quality is:

– Compatible with and applicable to the environmental conditions to which the steel will be exposed and the protective coating system to be used;

— Within the capacity of the specified cleaning procedure.

The above three international standards cover the following aspects of steel substrate preparation:

— ISO 8501 (all parts) : Visual assessment of surface cleanliness;

— ISO 8502 (all parts) : Surface cleanliness assessment tests;

— ISO 8504 (All Parts) : Surface treatment method

Each of these international standards is divided into separate sections.

The main objective of the finish is to ensure the removal of harmful substances and to obtain a surface that allows satisfactory adhesion of the primer to the steel. It also helps reduce the amount of contaminants that cause corrosion.

This document describes how to clean hand and power tools. It should be read in conjunction with ISO 8504-1.

Hand and power tool cleaning is a surface treatment method that usually provides a lower surface cleanliness than that achieved by sandblasting. These methods in most cases require the use of multiple types of power tools when results similar to sandblasting cleaning are required, making the surface treatment complex and expensive. Oil, grease and corrosion irritants such as chlorides and sulfates are usually not removed.

Power tool cleaning usually provides a better base for primer than hand tool cleaning, resulting in better paint performance.

Both hand and power tool cleaning are suitable surface treatments. Hand tool cleaning in particular requires the use of a primer with good surface wetting ability. Power tool cleaning is appropriate when a higher quality finish grade is required, sandblasting cleaning is not allowed or is not considered feasible by interested parties.

Representative photographic examples of St 2, St 3, PSt 2, PSt 3, and PMa (see ISO 8501-1 and ISO 8501-2) for evaluation of some new and previously coated steel surfaces cleaned using hand or power tools. Since many different situations arise during surface preparation and these photographs are not always sufficient to describe specific instances, it is recommended that special photographs of treated reference areas acceptable to all parties be made as the basis for further surface preparation procedures.

ISO 8504-3-318 “Preparation of steel substrates before application of paints and related products – Surface treatment methods – Part 3: Cleaning by hand and power tools”

1 range
This document describes methods for cleaning steel substrates with hand and power tools prior to applying paint and related products. It is suitable for both new steel structures and previously coated steel surfaces that show areas of decomposition that require maintenance paint. It describes the equipment to use and the procedures to follow.

2 Normative references

The following files are referenced in the text in such a way that some or all of the content constitutes the requirements of this document. For dated references, citation-only versions apply. For undated references, the latest version of the reference (including any revisions) applies.

ISO 8501-1, Preparation of steel substrates prior to painting and related products – Visual assessment of surface cleanliness – Part 1: Rust classes and preparation classes of uncoated steel substrates and steel substrates after the overall removal of prior coatings

ISO 8501-2, Preparation of steel substrates prior to painting and related products – Visual assessment of surface cleanliness – Part 2: Preparation grade of previously coated steel substrates after local removal of prior coatings

3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.

3.1 Cleaning Hand Tools

A method of preparing steel substrates using hand tools without power assistance

Note 1: chipping mallet, hand scraper, hand wire brush, sandpaper, and plastic wool embedded with abrasive are usually used. Sometimes hand tool cleaning is done initially to remove relatively loose contaminants before using power tools.

3.2 Clean Power Tools

A method for preparing steel substrate using a power-assisted hand tool, but excluding shot blasting cleaning

Note 1: Rotary descaler, rotary wire brush, rotary impact tool, sander, sander, rotary abrasive coated paper wheel (turning wheel), abrasive grinder, plastic wool with embedded abrasive, chipping hammer and needle gun, driven by electric or pneumatic, or connected to remote or robotic equipment, are examples of equipment commonly used.

3.3 Water, solvent or chemical cleaning

Method of removing visible oil, grease, dirt or processing lubricants and other soluble contaminants from steel surfaces

Note 1: For more details and cleaning methods, see ISO 12944-4:2017, 6.2.

3.4 Contaminated surfaces

A surface with substances that are harmful to the performance of the protective coating system

Note 1: Typical contaminants include slag, rust, laminate rust, mill scale, oil, grease, flux and weld spatter, soluble iron corrosion products, and other soluble salts, including chloride and sulfate.

3.5 Cleaning Surfaces

A surface where contaminants have been removed to a specified or agreed surface cleanliness level

Note 1 Full details are provided in ISO 8501-1 and ISO 8501-2.

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