ISO 8504-4-222 “Preparation of steel substrates before the use of paints and related products – Surface treatment methods – Part 4: Pickling”


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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.

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

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ISO 8504-4-222 “Preparation of steel substrates before the use of paints and related products – Surface treatment methods – Part 4: Pickling”

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:

— The presence of rust and dirt;

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

– Surface outline.

ISO 8501, ISO 8502 and ISO 8503 series provide methods for assessing these factors. However, the ISO 8504 series 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.

This document describes pickling, an effective surface treatment method. It is widely used because this surface treatment method has many of the versatile functions listed below.

a) In general, equipment is fixed, but can be moved.

b) This method is suitable for most types and forms of steel surfaces, especially those deformed by sandblasting.

c) Removal of rust or mill scale and traces of non-steel metal from inside, outside and complex structural surfaces.

d) Pickling can be used for decorative and/or aesthetic purposes.

The Purchaser’s purchasing document shall include several items to supplement this document. Surface defects should be considered prior to surface treatment and coating application. ISO 8504 series does not contain recommendations for surface cleaning of equipment and cleaning of pipelines (e.g. chemical pipelines, petroleum pipelines).

The ISO 8504 series does not contain recommendations for the application of protective coating systems to steel surfaces. The ISO 8504 series does not contain recommendations for surface quality requirements for specific cases, even if surface quality has a direct impact on the choice of protective coatings and their properties. These recommendations are found in other documents such as national standards and codes of practice. ISO 8504 series is used to ensure that the specified quality is:

a) Compatible with and applicable to the environmental conditions to which the steel will be exposed and the protective coating systems to be used;

b) within the scope of prescribed cleaning procedures.

Warnings The procedures described in this document are intended to be performed by appropriately trained and/or supervised personnel. The substances and procedures used in these methods can be hazardous to health if appropriate precautions are not taken. The text draws attention to some specific dangers. This document relates only to the technical applicability of the method and does not exempt the user from statutory obligations relating to health and safety.

ISO 8504-4-222 “Preparation of steel substrates before the use of paints and related products – Surface treatment methods – Part 4: Pickling”

1 range
This document describes typical methods commonly used in shop facilities for pickling to prepare steel substrates prior to application of paints and related products. It is usually suitable for new steel structures.

This method is basically to remove rust and dirt. Usually, only slight oil residue can be removed during this process. It can be used on steel surfaces that are easily deformed by sandblasting.

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 8502 (all parts), Preparation of steel substrate – Surface cleanliness Assessment tests prior to coating of paints and related products

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

3.1 Pickling

Treatment for removal of rust and scaling from steel substrates by acidic solutions usually containing inhibitors (3.3)

3.2 Acid lotion

A liquid mixture of etching components (organic, inorganic, and/or complexing agents), inhibitors (3.3), and usually surfactants (3.4)

3.3 Inhibitors

A chemical or mixture of substances that, when added to a medium solution in a given concentration and form, reduces the rate of pickling of metals while maintaining most of the rate of pickling of metal oxides such as rust and dirt

3.4 Surfactant

A substance that can significantly alter the interfacial state of a solution system (reducing surface energy) and increase degreasing capacity

3.5 Fresh Water

Water with an electrical conductivity of less than or equal to 1 200 μS/cm (at 25°C), or water of a purity and quality sufficient to prevent the surface to be cleaned from meeting the standards for surface cleanliness or invisible contaminants specified in the procurement documents (Project Specifications)

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