Tools for assessment of corrosion and soiling in the multipollutant

situation

Johan Tidblad and Vladimir KuceraCorrosion and Metals Research Institute,

Stockholm, Sweden

Corrosion trends in Europe in the multipollutant situation

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Limestone

Steel

Zinc

MULTI-ASSESS (2002-2005)

Fifth Framework Programme,Energy, Environment and Sustainable Development

Key Action: City of Tomorrow and Cultural Heritage

Contract number: EVK4-CT-2001-00044

Partners and subcontractors

Swedish Corrosion Institute, Stockholm (co-ordinator)Academy of Fine Arts, Inst. of Sciences and Technologies In Art, Vienna, AustriaBavarian State Department of Historical Monuments, Munich, GermanySwiss Federal Labs. for Materials Testing and Research (EMPA), DubendorfSwedish Environmental Research Institute Ltd. (IVL), GothenburgCNR Institute for Atmospheric Pollution, Rome, ItalyUniversity of Athens, Department of Applied Physics, GreeceMiddlesex University, School of Health and Social Sciences, London, UKSVUOM, Prague, Prague/Czech RepublicBuilding Research Establishment (BRE), Watford, UKNorwegian Institute for Air Research (NILU), KjellerInstitute of Precision Mechanics, Warzaw, PolandRiga Technical University, Centre for Conservation of Stone Materials, LatviaLISA - Université Paris XII, FranceEstonian Environment Research Centre (EERC), TallinnUniversity of Antwerpen, Department of Chemistry, Belgium

Expected main results

Passive samplers for the ”missing” pollutants : nitric acid and particles

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HNO3 concentration

Relation of particle deposition and PM10 concentration

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PM10 µg m-3

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Dose-response functions, ICP Materials (period 1987-95)

asheltered onlybunsheltered only

Material SO2 NO2 O3 H+ Cl- Carbon steel x xWeathering steel xZinc x xAluminium x xCopper x x xCast bronze x x xNickela x (x)Tina x (x)Alkyd/galvanisedb xSilicon alkyd/steelb xSandstone x xLimestone x xGlass x x x

Dose-response functions multi-pollutant/MULTI-ASSESS programme

incl. HNO3 and PM10 (1997-2001)

Material T Rh SO2 NO2 O3 HNO3 PM10 Rain pH

carbon steel X X X X X X

zinc X X X X X X

copper X X X X X X

bronze X X X X X X

limestone X X X X X X

glass X X X X

SO2 dependence

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SO2 dominating situation (ICP Materials)

multi-pollutant situation (MULTI-ASSESS)

Tolerable corrosion and pollution

The tolerable level is the maximum level at which a tolerable corrosion/soiling occurs. It should be based on experiences from

restoration / maintenance work for cultural heritage objects.

Soiling, limestone

DRF: ΔR/R0 = [1-exp(- klimestone x PM10 x t)]

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Time / years

PM10 / µg m-3

ΔR/R0, relative loss of reflectance

k, soiling constant

PM10, in µg m-3

t, time in years

Critical soiling level ΔR/R0 = 35%

Tolerable pollution levels in the multi-pollutant situation

Definition of a tolerable corrosion rate, Kt, depending on use and material, implicitly defines a tolerable multi-pollution situation, which can be reached by reducing one or several of the multi-pollutants:

Kt= fdry(T, RH, [SO2]t, [HNO3]t, ...)

+ fwet(Rain[H+]t)

Summary of DRF, tolerable effects and target levels

Effect

Material

SO2 HNO3 PM Tolerable

effect

Target

SO2 levela

Target

PM10 level

Zinc X X 1.1 µm year-1

Corrosion Carbon steel X X 20 µm year-1 10 µg m-3

Limestone X X X 8 µm year-1

Painted steel X 35% loss of

Soiling White plastic X reflectance 15 µg m-3

Limestone X in 10-15 years athis level will protect about 80% of the areas. For a complete protection, levels of N-pollutants,

especially HNO3 also need to be considered.

Air Quality Directive 99/30/EC

SO2 NO2 PM10

Urban zones – health effects

Hourly limit value 350 200

Daily limit value 150 50

Annual limit value 40 40

Rural areas - ecosystems

Annual limit value 20 30

Limit values of pollutants, µg m-3

Use of DRF for mapping:Steel, Czech Republic (2001)

14.9 – 18.6 µm

18.6 – 20.5 µm

20.5 – 22.4 µm

22.4 – 24.4 µm

24.4 – 30.7 µm

The tolerable corrosion rate is 20 µm

Kit for assessment of deterioration and pollution

Carousel with limestone specimens

Soiling sampler Passive samplerspollutants

Steel and zinc specimens

Tools developed for assessment of corrosion and soiling

FOR NATIONAL AND INTERNATIONAL POLICY

• Dose-response functions for multipollutant situation: - Tolerable deterioration, tolerable pollution levels - Mapping of areas with exceedance - Calculation of cost of damage

FOR LOCAL MANAGEMENT STRATEGIES

• DRF – tolerable pollution levels, tolerable deterioration• Kit for rapid assessment of corrosion and soiling• Passive samplers for nitric acid and particles

Conclusions andgaps of knowledge

• The new corrosion functions for the multi-pollutant situation involve, besides the effect of SO2, also the effect of particulate matter and HNO3.

• Assessment of target levels for materials show that they are at least as sensitive to pollution as human beings and therefore cultural heritage should be considered in future assessment of limit values for pollutants.

• The effect of traffic, in particular in the vicinity of main roads, is only in part covered by the new equations. Therefore, future efforts should focus on the corrosion and soiling effects of particular matter, nitric acid and other pollutants, for example those associated with the use of alternative fuels, in the traffic situation.

<Additional figures>

Dose-response function for zinc from ICP Materials (N=98, R2=0.84)

ML = Dry deposition + Wet deposition =

1.4[SO2]0.2·e0.02Rh + f(T)·t0.85 + 0.03Rain[H+]·t

ML = Corrosion attack (mass loss)T = TemperatureRH = Relative humidity[SO2] = SO2 concentration (air)

Rain = Amount of precipitation[H+] = [H+] concentration (precipitation)t = exposure time

Tolerable corrosion rates

For practical purposes, tolerable corrosion rates (Kt) can also be defined as a multiple (n) of the background corrosion rate (Kb), where n is based on experiences from restoration / maintenance work for cultural heritage objects:

Kt = n · Kb

Tolerable corrosion rate based onbackground corrosion rates and n=2.5

Material

Background corrosion rate

Tolerable corrosion rate

Limestone 3.2 µm year-1 8 µm year-1 Sandstone 2.8 µm year-1 7 µm year-1 Copper 0.34 µm year-1 0.8 µm year-1 Bronze 0.25 µm year-1 0.6 µm year-1 Zinc 0.46 µm year-1 1.1 µm year-1 Carbon steel 8.5 µm year-1 20 µm year-1

Example of use: tolerable SO2 levels

Parameter

Scenario 1 “average”

Scenario 2 “urban”

Temperature Relative humidity Precipitation

10.3 oC 73.2 %

604 mm year-1 pH level 5.0 O3 concentration 47 µg m-3 33 µg m-3 NO2 concentration 19 µg m-3 56 µg m-3 HNO3 concentration 0.82 µg m-3 1.16 µg m-3 PM10 concentration 37 µg m-3 72 µg m-3

Material

Scenario 1 “average”

Scenario 2 “urban”

Limestone 25 µg m-3 9 µg m-3 Copper 5 µg m-3 13 µg m-3 Bronze 21 µg m-3 9 µg m-3 Zinc 11 µg m-3 5 µg m-3 Carbon steel 11 µg m-3 6µg m-3