Environment Product Declaration for Galvanizing
Life Cycle Inventory (LCI)
LCI data is a vital tool for the detailed study of the life-cycle environmental impacts of products and services. However, LCI data is not easy for product users to interpret and it is now increasingly common to communicate environmental performance through the simpler format of an environmental product declaration (EPD). EGGA has developed a Pan-European LCI study of an average galvanized steel product.
The final result of that work was a life-cycle inventory data set for the batch galvanizing process, based on data submitted by members of EGGA National Associations from their own operations according to ISO 14040/14044. The average energy, resource consumption and emission of substances to the environment, resulting from a LCI of a representative sample of plants operating at European level, were calculated according to the defined system boundaries.
Environmental product data for batch galvanizing is available for users and policy makers.
European General Galvanizers Association (EGGA) is the industry organization for Europe’s general galvanizing sector. It is a federation of the National Associations across Europe. It is an industry that comprises just over 600 general galvanizing plants.
This EPD is a sector-wide declaration based on a sample of galvanizing plants affiliated with EGGA and representative of European production, defined as the EU27 plus the United Kingdom and EFTA countries. The analyzed sample accounts for over 940 000 tonnes of production within EGGA’s membership, corresponding to approximately 13% of the total production in Europe (EU27+UK+EFTA).
Data were gathered from 54 companies across 10 countries, covering plants considered highly representative of the European hot dip galvanizing industry. Data collection was carried out using an excel-based questionnaire developed by LCA specialists under the guidance of industry experts from EGGA. The sample was designed to include relevant countries and processes, ensuring a representative mix of production that covers heavy, medium, and light steel products.
The results are considered representative of the sector at European level in terms of technology, bath size, method of bath heating and product types.
| Substrate | Steel plate with Dimension 1m x 1m x 8mm and weight of 62.4kg |
|---|---|
| Galvanized coating thickness (as EN ISO 1461) | 85 microns |
| Exposure environment | Corrosivity category C3 (as defined by ISO 9223) with an average zinc corrosion rate of 1.35 microns per year |
| Predicted maintenance-free galvanized coating life | Minimum 63 years |
| Functional unit (results) | Burdens per year of protection |
Hot dip galvanizing is the most effective treatment for steel corrosion protection and can be applied to a wide range of steel products that are characterised by many different dimensions, geometries and functions. The operational sequence of the plant is essentially the same and the dimension of the kettles (i.e., the bath of molten zinc) is determined by the typical mix of products to be coated. For example, small components are normally processed by companies operating smaller kettles. Galvanizing is a corrosion protection process for steel, in which the steel is coated with zinc to prevent it from rusting. The process involves dipping cleaned iron or steel components into molten zinc (which is usually at around 450°C).
A series of zinc-iron alloy layers are formed by a metallurgical reaction between the iron and zinc creating a strong bond between steel and the coating. A typical time of immersion is about four or five minutes, but it can be longer for heavy articles that have high thermal inertia or where the zinc is required to penetrate internal voids. Upon withdrawal from the galvanizing bath, a layer of molten zinc will be deposited on top of the alloy layer stopping corrosion of steel in two ways a physical barrier and electrochemical protection.
Typical coating thicknesses can range from 45μm to over 200μm and in case of damaged area, a galvanic cell is formed: the zinc around the point of damage corrodes in preference to the steel and forms corrosion products that precipitate on the steel surface and protect it.
The hot dip galvanized coating is applied according to the requirements of EN ISO 1461. In accordance with ISO 14713-1:2009, the technical lifespan of the zinc coating is estimated at 63 years for corrosion class C3, assuming a medium corrosion risk and an average zinc thickness loss of 1,35 μm per year.
The galvanizing industry also works closely with the steel construction industry at national level to ensure that transparent and robust environmental data is available for galvanized steel products where it is required:
- In Germany, bauforumstahl e.V. and Industrieverband Feuerverzinken e.V. has cooperated to publish an EPD “Hot-dip galvanized structural steels: Open rolled sections and heavy plates” in accordance with the requirements of the Institut Bauen und Umwelt e.V.
- In the Netherlands, Zink Info Benelux has worked with steel industry partners to include data on galvanized steel in the national Milieu Relevant Product Informatie (MRPI) database for construction products.
- In France, Galvazinc has prepared a Fiche de Déclaration Environnementale et Sanitaire (FDES) for galvanized steel.
Sector EPD for Galvanizing
EGGA has published an Environmental Product Declaration (EPD) for ‘Batch Hot Dip Galvanizing of Steel Products to EN ISO 1461 – European Average’.
The EPD has been generated under the International EPD System® and is verified in accordance with ISO 14025:2010 and EN 15804.
Batch galvanizing is most often specified early in the design of steel components and structures with the coating application being sub-contracted much later in the supply process. For this reason, a sector-based EPD is the most informative approach for architects and designers when considering environmental information. Environmental burdens of the galvanized coating are separated from that of the steel plate – to demonstrate that the additional burden of providing lifelong protection for steel components is extremely small.
LCA Information
Data are presented for 1 year of protection by galvanizing to ENISO 1461 of 1m x 1m steel plate of 8mm thickness, calculated on the basis of the life span (63 years) predicted using EN ISO14713-1.
The data contained in this EPD refer to an hypothetical reference steel product, consisting of a steel plate with two side seach of of 1m x 1m and a thickness of 8 mm. Results presented include both the steel plate and hot dip galvanizing process.The mass of the galvanizing coating per unit surface area for given steel products (grams per square meter) is defined by ENISO 1461, and this specified coating mass determines the durability of the coating during its service life. For a given environment,
the service life is directly proportional to the thickness of the galvanizing coating (i.e., the coating mass per surface area).
The expected durability of the zinc coating is assessed according to ISO ISO 14713-1. Reference is made to class C3, with a medium corrosion risk and zinc corrosion rate between 0,7 and 2,0 μm/year. The calculations were carried out using the average coefficient value (1,35 μm/year). The resulting service life is 63 years.
Data quality assessment was implemented in the study considering the requirements of GPI version 5.0.1 and the reference PCR 2019:14 version 2.0.1 (referring to EN 15941)
Batch Hot Dip Galvanizing of Steel Products to EN ISO 1461 Sector EPD Based on an Average Product
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