ISO 12944-4:2017

Overview

ISO 12944-4:2017 is Part 4 of the ISO 12944 series on protective paint systems for steel structures. It specifies the types of surfaces found on carbon and low-alloy steel and gives guidance on their surface preparation prior to painting. Covered surface types include uncoated steel, thermally sprayed (zinc/aluminium/alloys), hot‑dip‑galvanized, zinc‑electroplated, sherardized, surfaces with prefabrication primer, and other painted surfaces. The standard defines a range of surface preparation grades and addresses methods for cleaning and preparing surfaces, surface profile (roughness) and assessment, temporary protection, and preparation of existing metal coatings. Note: highly polished and work‑hardened surfaces are excluded, and ISO 12944-4:2017 does not set requirements for substrate condition prior to preparation.

Key Topics

• Types of surface covered: uncoated, thermally sprayed, hot‑dip galvanized, zinc‑electroplated, sherardized, prefabrication‑primed, other painted surfaces.
• Surface preparation methods: water, steam and solvent cleaning; chemical treatment; mechanical cleaning (hand/power tools); blast‑cleaning; water jetting.
• Surface preparation grades: standardized grades for primary (overall) and secondary (local) preparation; guidance on selecting grades for different substrate/coating combinations.
• Surface profile and roughness: guidance on acceptable surface profiles to ensure coating adhesion and performance.
• Assessment and temporary protection: how to assess prepared surfaces and protect them from corrosion/contamination before coating application.
• Special preparations: procedures for hot‑dip‑galvanized, thermally sprayed metal, zinc‑electroplated and sherardized surfaces.
• Health, safety and environmental considerations related to cleaning and preparation operations.

Applications and Users

ISO 12944-4:2017 is essential for professionals involved in corrosion protection and coating specification:

• Asset owners and facility managers specifying corrosion protection for steel structures
• Structural and coating engineers, paint system designers and specifiers
• Contractors and applicators performing surface preparation and painting
• Inspectors and quality assurance personnel assessing surface condition and preparation grade
• Manufacturers of coating materials needing to reference surface preparation standards

Practical uses include writing technical specifications, selecting cleaning and blasting methods, defining surface profile requirements, and preparing tender documents for coating contracts.

Related Standards

ISO 12944-4:2017 is part of the ISO 12944 series and normatively references standards such as:

• ISO 1461 (hot‑dip galvanized coatings)
• ISO 2063 (thermal spraying - zinc/aluminium)
• ISO 4628 (evaluation of coating degradation)

For corrosion protection projects, combine ISO 12944-4:2017 with other parts of ISO 12944 and relevant surface preparation standards to ensure comprehensive specifications.