Guide To Protection Of Steel Against Corrosion

infosteelGuide to protection ofsteel against corrosionIndoor and outdoor structures1st edition: May 2012Value 10 EUR

1Introduction.1.1 ForewordThis guide has been drawn up based on the following publications: ECCS – Technical Committee 4 – Surface Protection, Technical NoteN 90, Surface Protection Guide for Steelwork in Building Interiors andFacades, First Edition (1997);ECCS – Technical Committee 4 – Surface Protection, Technical NoteN 98, Surface Protection Guide for Steelwork exposed to AtmosphericEnvironments, First Edition (1998).The information from the above publications has been updated taking intoaccount the development of the standards and the state of technologycurrently applied in the Belgian and Luxembourg markets.This guide describes solutions for protecting steel structures againstcorrosion, irrespective of whether these structures are located insidebuildings or whether they are exposed to the outside air. The guide has beenprepared by a working group consisting of experts in the field of protection ofsteel against corrosion and those working with the following organizations: Infosteel (www.infosteel.be); VOM vzw. the Belgian association forsurface technologies of materials (www.vom.be); Stichting Zinkinfo Benelux (www.zinkinfobenelux.com); the ‘Mobility and Public Works’ department of theFlemish Region (www.vlaanderen.be).1.2 GeneralThe purpose of this guide is to provide guidance to all participants in theconstruction industry (clients, architects, consulting engineers etc.) involvedin the design, the actual construction, the maintenance and the renovation ofsteel structures. There are a number of solutions recommended for corrosionprotection, based mainly on the corrosivity class (C1 to C5).The anticorrosive systems described in this document are based onreference standards or codes of practice.This guide contains a non-exhaustive list of existing corrosion protectionsystems. Only the most frequently used and the most appropriate solutionsare proposed. It is possible that other acceptable solutions exist forspecific projects that are not described here.1.3 Innovative systemsNew corrosion protection systems are constantly being developed and put onthe market. That those systems are not included in this guide says nothingabout their performance. The explanation is that these systems arecontinuously under development or that there are no existing practicalguidelines for them.1.4 Environmental regulationsAttention is drawn to the fact that the environmental regulations oncorrosion-resistant products are constantly becoming stricter and that theydepend on the location where they are used. It is up to the differentparticipants to determine whether the systems used comply with theenvironmental regulations.1.5 Specific conditionsIn order to choose the optimal protection system, for each project accountmust be taken of the specific conditions that apply to the structures (indooror outdoor application, visible or hidden structure, accessibility, etc).2. Atmospheric corrosionAtmospheric corrosion plays a role in structures which are neither buried norsubmerged in a liquid (usually water). The corrosion of buried or submergedstructures is dealt with in § 3.2.The risk of atmospheric corrosion and the rate at which this corrosionoccurs are primarily dependent on the following parameters: the relative humidity of (inside or outside air) where the steelstructure is located;the risk of condensation (depending on the relative humidity, thetemperature of the steel and the speed at which the air is moving);the concentration of corrosive pollutants (gases, solids or liquids),such as sulphur dioxide, acids, alkalis or salts.The solutions for protection against corrosion for the corrosivity class C2 toC5 (atmospheric corrosion) are described in the central table of thisdocument.3. Exceptional cases 3.1Corrosivity class C1Corrosivity class C1 corresponds to the neutral interior atmosphere of adry and heated building. In this class non-visible elements (loweredceilings, attics, etc.) require no anticorrosive treatment, except someconstructions that are built into the masonry (see § 3.3, 2nd situation).When elements in a class C1 interior atmosphere are visible, for aestheticreasons and with a view to easy cleaning, it may however be desirable toprovide a minimum level of protection, such as the 2/2-system.It should be pointed out that a dry and heated building where no neutralatmosphere prevails (presence of corrosive gases or chlorides) falls undera higher corrosivity class.

3.2Corrosion with buried or submergedstructures1st situation: the steel structure isprotected against water from the outsideWhen the steel structure is protected against water from the outside, thechoice of the anticorrosion system is based on the corrosivity class thatcorresponds to the interior atmosphere of the building.With buried or submerged structures, the choice of an anti-corrosionsystem depends on a large number of parameters. This is a complexchoice wherein a specialist should be consulted. These special situationsare therefore not dealt with in this guide.COMMENTS: The following parameters must be taken into account with buriedstructures: chemical composition, water content, degree of soil aerationand mechanical load. With submerged structures account must be taken of the salt contentand the chemical composition of the water and any cycles of immersionand drying (which are determining for the submerged zone, the transitionzone and the splash zone).3.3Structures worked intothe masonryThis situation occurs in the following cases: when the outer cavity leaf of the building is water tight (Figure 1a) when the steel structure is protected against water infiltration: either by a layer of air of at least 40 mm (Figure 1b) - or by acontinuous, impermeable layer of material at least 25 mm thick(Figure 1c).2nd situation: the structure is possiblyexposed to water from the outside.When there is a risk that the steel structure is exposed to water from theoutside, hot-dip galvanizing is a suitable protection solution for an interioratmosphere of class C1 to C4.When steel structure elements are located in the outer wall of a building andthey are not fully visible or accessible, the choice of the anticorrosion systemcan not always be based on the corrosivity class of the interior atmosphere ofthe building. There are two possible situations.This applies for the majority of cases where the steel structure directly(Figure 2a) or indirectly (Figure 2b) comes into contact with the nonwatertight outer cavity leaf of the building. 25 mm 40 mma.b.Figure 1: the steel structure is protected against water from the outside (horizontal cross-section)a. Watertight outer cavity leafb. Non-watertight outer cavity leaf - Presence of a layer of airc. Non-watertight outer cavity leaf - Presence of an intermediate layer in a watertight materiala.b.Figure 2: the steel structure is exposed to water from the outside (horizontal cross-section)a. Non-watertight outer cavity leaf - Steel structure in contact with the outer cavity leafb. Non-watertight outer cavity leaf - Presence of an intermediate layer in a watertight materialc.

4. Reference documentsEN ISO 1461 : 2009Hot-dip galvanized coatings on fabricated iron and steel articles - Specifications and test methodsEN ISO 2063 : 2005Thermal spraying – Metallic and other inorganic protective coatings - Zinc, aluminium and their alloysEN ISO 4628-3 : 2003Paints and varnishes - Evaluation of degradation of coatings - Designation of quantity and size of defects, and of intensity ofuniform changes in appearance* Part 3: Assessment of degree of rusting (ISO 4628-3:2003)ISO 8501-1 : 2007Preparation of steel substrates before application of paints and related products. Visual assessment of surface cleanliness.* Part 1: rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal ofprevious coatingsISO 9223 : 1992Corrosion of metals and alloys – Corrosivity of atmospheres - ClassificationEN ISO 12944Parts 1 to 4: 1998Paints and varnishes – Corrosion protection of steel structures by protective paint systems* Part 1: General informationPart 5: 2007* Part 2: Classification of environmentsParts 6 to 8: 1998* Part 3: Design considerations* Part 4: Types of surface and surface preparation* Part 5: Protective paint systems* Part 6: Laboratory performance test methods* Part 7: Execution and supervision of paint work* Part 8: Development of specifications for new work and maintenanceEN ISO 14713Parts 1 and 2: 2009Protection against corrosion of iron and steel in structures -- Zinc and aluminium coatings - Guidelines* Part 1: General principles of design and corrosion resistance* Part 2: Hot-dip galvanizingEN 15773: 2009GSB ST 663Industrial application of powder organic coatings to hot dip galvanized or sherardized steel articles [duplex systems].Specifications, recommendations and guidelinesInternational Quality Regulations for the Piecework Coating of Steel and Galvanised Steel Building ComponentsEdition May 2011Belgian code of practiceBPR 1197 duplexQuality requirements for the industrial application of organic protective layers on intermittent hot-dip galvanized steel (duplexsystem)3rd revised edition September 2004Evio code of practiceDecember 2007Code of practice for the application of thermally sprayed layers (metallisation) on steel followed by an organicprotective layerA publication of Infosteel, In partnership with VOM vzw and Stichting Zinkinfo Benelux (Benelux Galvanizing Information Foundation.Belgian association for surfacetechnologies of materialsZinkinfo BeneluxinfosteelArianelaan 5 B-1200Brussels t. 32-2-50915 01 e.info@infosteel.bewww.infosteel.beKapeldreef 60 B3001 Leuven t. 3216-40 14 20 e.info@vom.bewww.vom.beSmederijstraat 2NL-4814 DB Bredat. 31-76-531-77 44e. info@zinkinfobenelux.comwww.zinkinfobenelux.comAll rights reserved. No part of this publication may be reproduced, stored in an automated data base, and/or made public in any form or by any means, electronic,mechanical, by photocopying, or in any other way, without prior written permission of the publisher.WarningThe greatest of care has been paid to this guide. Nevertheless, printing errors or other imperfections cannot be excluded. The publisher, and where necessary, allpersons who have contributed to this guide, disclaim any liability for any direct or indirect consequences of the use of this publication or that which may be incurred inconnection therewith.