Overview
EN ISO 12944-4:2017 - "Paints and varnishes - Corrosion protection of steel structures by protective paint systems - Part 4: Types of surface and surface preparation" is a CEN-endorsed harmonized standard that defines the types of steel surfaces and accepted methods to prepare them prior to coating. It applies to carbon and low‑alloy steel and covers uncoated, metal‑coated and painted surfaces (for example thermally sprayed zinc/aluminium, hot‑dip galvanized, zinc‑electroplated, sherardized, and prefabrication‑primed surfaces). The standard defines surface preparation grades and methods but does not set requirements for the substrate condition before preparation. Highly polished and work‑hardened surfaces are excluded.
Key topics and requirements
- Types of surfaces covered: uncoated steel, thermally sprayed (zinc/aluminium/alloys), hot‑dip galvanized, zinc‑electroplated, sherardized, prefabrication primer coatings and other painted surfaces.
- Surface preparation methods: cleaning (water, steam, emulsion, alkaline, solvent, stripping, acid pickling, chemical treatment), mechanical cleaning (hand‑tool, power‑tool), blast‑cleaning and water‑jetting.
- Preparation grades: defined standard grades for primary (overall) and secondary (local) preparation to ensure consistent adhesion and corrosion performance.
- Surface profile (roughness): guidance on profile grading is included to match coating system requirements.
- Assessment & temporary protection: procedures for assessing prepared surfaces and protecting them from corrosion/contamination before coating.
- Special preparations: dedicated sections for preparing hot‑dip galvanized, thermally sprayed, zinc‑electroplated and sherardized surfaces.
- Supporting topics: environmental/pollution considerations, health and safety, and Annexes (normative grades and informative removal procedures).
Practical applications and users
EN ISO 12944-4:2017 is essential for practitioners specifying, applying or inspecting protective paint systems on steel structures, including:
- Coating specifiers and architects creating durable protective systems for bridges, buildings, offshore structures, tanks and industrial installations.
- Steel fabricators and pre‑fabrication shops preparing surfaces (including prefabrication primers).
- Contractors and applicators using blast‑cleaning, water‑jetting or chemical treatments.
- Corrosion engineers and inspectors performing surface condition assessments and quality control.
- Asset owners and maintenance teams planning recoating and temporary protection strategies.
Using the standard helps ensure consistent surface quality, improved adhesion, and long service life of coating systems - reducing corrosion risk and lifecycle costs.
Related standards
- Part of the ISO 12944 series (protective paint systems for steel structures). Refer to other parts of ISO 12944 for corrosion categories, coating system selection, laboratory and site performance testing, and maintenance planning.
