How to choose the right paint systems
to protect your steel structure

The ISO 12944 standard is an international standard designed to assist anyone involved in the design and construction of steel structures. We have created this guide in accordance with the ISO 12944 standards to help explain the types of Pronto paint systems available for steel structures depending on different environments, surfaces and durability.

This guide is designed to help you choose the right paint based on your requirements.

Introduction

All steel structures, due to the nature of steel, will be affected by corrosion when it meets water and oxygen. Once steel is oxidised, it can occupy six times the volume of the original material, and consequently dramatically affect the structure. This makes it vital to protect steel as best as possible to limit damaging consequences and to protect the longevity of a structure.

To ensure you understand which Pronto paint systems are best suited to protect a given steel structure, we have written out this simple guide, in accordance with the latest edition of the ISO 12944 standards.

A – Select the Environment

First and foremost, before selecting a paint it is important to understand the conditions the structure operates in, and how exposed to corrosivity it may be.

This table gives you an idea of the corrosive environment of a given steel structure.

This can vary depending on the structures exposure to the following:

  • Humidity
  • Elevated temperatures
  • Chemicals
  • UV radiation
  • Mechanical works
Corrosive Environment Typical Environments
ISO 12944-2 Exterior Interior
C1 – Very Low Heated buildings with clean atmospheres, eg offices, shops, hotels and schools
C2 – Low Atmospheres with low level of pollution. Mostly rural areas Unheated buildings where condensation may occur, eg sports halls, warehousing
C3 – Medium Urban and Industrial atmospheres, moderate sulphur dioxide pollution. Coastal areas with low salinity Production rooms with high humidity and some air pollution, eg food processing plants, laundries, breweries and dairies
C4 – High Industrial areas and coastal areas with moderate salinity Chemical plants, swimming pools, coastal boatyards
C5I – Very High (Industrial) Industrial areas with high humidity and aggressive atmospheres Buildings or areas with almost permament condensation and with high pollution
C5M – Very High (Marine) Coastal and offshore areas with high salinity Buildings or areas with almost permament condensation and with high pollution
Most projects take place in and around the city, this is normally classified as a C3 environment.

B – Select the Durability

Secondly, you must select how long you want your paint system to last before you do any major maintenance to the paint work.

System Durability Years To First Major Maintenance
Low Less than 5 years
Medium 5 to 15 years
High More than 15 years
Depending on the quality of the paint, you will have to maintain the paint job more or less often. ISO 12944 specifies a range of time frames.

C – Select a Pronto paint system

The Pronto paint system you choose will depend on the corrosive environment the said structure lives in, and the preferred durability time frame before the first maintenance is needed.

This table indicates what types of Pronto paint systems
you should be looking at depending on your requirement.

For example, if the structure you wish to paint is located in a C3 environment and you wish to not have to do any maintenance for at least the next 5 years, you will be looking at Pronto paint systems P11, P51 or P56. For more information about these systems please refer to the last table.

Corrosive Environment Typical Environments
Low Medium High
C1 P10 P10 P10
C2 P10, P11, P50 P11, P50 P11, P51
C3 P11, P50, P56 P11, P51, P56 P52, P56
C4 P53, P55 P53, P55 P54, P55
C5I P55 P55
C5M P55 P55

Information about the Pronto paint systems mentioned – all these products are in accordance with the ISO 12944 standards

Pronto System Product Reference Dry Film Thickness
(microns)
ISO 12944-5
System Ref
Product System
P10 200:026   QD Industrial Primer
202:000   QD Gloss Finish
50
30
80 A2.01
P11 450:004   ProTect Vinyl 160 160 A3.05
P50 100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finis
80
40
120 A2.06
P51 100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finis
80
80
160 A2.07
A3.08
P52 100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finis
140
60
200 A3.09
P53 100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finis
160
80
240 A4.08
P53 100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finis
200
80
280 A4.09
P55 103:026   2 Pk Epoxy Zinc Rich
100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finish
60
130
50
240 A4.12
A5I.04
A5M.05
P56 103:026   2 Pk Epoxy Zinc Rich
100:006   2 Pk Epoxy Primer
360:000   2 Pk Poly Finish
60
50
50
160 A3.11

The above systems are based upon a low alloy carbon steel substrate.

 

To download a brochure please click here.