GLP Metal Corrosion Testing for Transport Classification and Regulatory Compliance

Reliable metal corrosion testing according to UN Test C.1 is essential for classification under the UN Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria, Chapter 37.4, and supports compliance with international transport regulations, including ADR, RID, IMDG and ICAO/IATA. The test determines the corrosive effects of liquids and solids that may liquefy during transport on commonly used metals.

At LAUS, we perform GLP-compliant UN C.1 Metal Corrosion Tests for chemicals, biocidal products, formulations and other industrial products. Our experienced scientists generate robust data that support transport classification and regulatory submissions.

What Is the UN Test C.1?

UN Test C.1 is described in Chapter 37.4 of the UN Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria. The method determines whether a liquid substance or mixture is corrosive to steel and aluminium and provides data for transport classification under international dangerous goods regulations and safety data sheets (SDS).

Test Principle

In a standardized system, metal plates made from Aluminium and Steel will be immersed, dipped halfway and hung in the gas phase of the test solution at 55 °C for 1-4 weeks. Mass loss and localized corrosion will be assessed

Metal specification:

·      Steel (S235JR+CR (1.0037 resp. St 37-2), S275J2G3+CR (1.0144 resp. St 44-3) or SAE 1020)

·      Aluminium (non-clad types7075-T6 or AZ5GU-T6)

Regulatory Endpoints of UN Test C.1

The endpoints of the study are the mass loss of the individual plates and the depth of local corrosion (with the highest value being used for classification). The results are used to determine whether a substance meets the criteria for "Corrosive to Metals" (UN Class 8) under the UN Model Regulations. In case of a positive result the product will be classified as packing group III for shipping and Corrosive to Metals – Category 1 for GHS.

Classification in Packaging groups

The UN Manual of Tests and Criteria (Eighth revised edition) provides in Section 37 the classification scheme and the method for the “test for determining the corrosive potential of liquids and solids that may become liquid as a substance corrosive to metals, packaging group III/category 1”.

As stated in the Manual, corrosivity towards skin shall be considered for the classification in Packing Groups according to degree of danger in transport (chapter 2.8 of the Model Regulations). Please, find options for OECD 435 or OECD 431 testing here.

Metal Corrosion Testing for Biocidal Products

For Biocidal Products the Technical Agreements for Biocides (TAB) – APCP Version 4.4 provides additional requirements, that can easily be implemented in our lab:

·      Products containing as corrosion inhibitor need to be tested for 4 weeks

·      For products containing reactive or unstable corrosive compounds the test solution should be refreshed in appropriate intervals, or analysis needs to prove the stability of the compounds (examples are hydrogen peroxide or organic peroxides)

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Looking for a reliable GLP laboratory for Metal Corrosion Testing according to UN Test C.1 (Chapter 37.4)?

Our experts are happy to discuss your project and prepare a customised study proposal tailored to your regulatory requirements.

Frequently Asked Questions (FAQ)

What is UN Test C.1?

UN Test C.1 is the internationally recognised method described in Chapter 37.4 of the UN Manual of Tests and Criteria for determining whether a liquid substance or mixture is corrosive to metal. The results are used for the classification of dangerous goods during transport.

When is a UN C.1 Metal Corrosion Test required?

A UN C.1 study is required when experimental data are needed to determine whether a substance or mixture is corrosive to metals for transport classification.

Which regulations require UN Test C.1?

The study supports classification according to international dangerous goods regulations, including ADR, RID, IMDG Code, ADN, ICAO/IATA, and the UN Model Regulations. It also provides data used for Safety Data Sheets (SDS).

Which metals are used in the test?

The guideline specifies testing on steel (S235JR+CR (1.0037 resp. St 37-2), S275J2G3+CR (1.0144 resp. St 44-3) or SAE 1020) and aluminium (non-clad types7075-T6 or AZ5GU-T6).

Which materials can be tested?

UN Test C.1 is suitable for many liquid products, including industrial chemicals, biocidal products, formulated products, cleaning agents, detergents, acids, alkalis, specialty chemicals and chemical intermediates, as well as solids that may liquify during transport.

What is the classification criterion for corrosive to metals?

According to the UN Manual of Tests and Criteria, a substance may be classified as corrosive to metals if the corrosion rate on steel or aluminium exceeds the specified regulatory threshold. The study provides the experimental data required to support hazard classification.

Is the study performed under GLP?

Yes. LAUS performs UN Test C.1 studies in compliance with the principles of Good Laboratory Practice (GLP), ensuring traceable study conduct, high-quality documentation and regulatory acceptance.

Can difficult or complex formulations be tested?

Yes. LAUS has extensive experience testing challenging materials, including highly acidic or alkaline products, viscous formulations, multi-component mixtures, surface-active substances and UVCBs. Study conditions are adapted where scientifically justified while remaining compliant with the UN Test C.1 guideline.