ISO 2160 Petroleum Products - Corrosiveness to Copper - Copper Strip Test

The ISO 2160 Petroleum products - Corrosiveness to copper - Copper strip test standard, published by the International Organization for Standardization (ISO), describes a method for determining the corrosiveness of liquid petroleum products and certain solvents to copper. This standard also covers volatile products with a maximum vapor pressure of 124 kPa at 37,8 degrees Celsius.

Volatile products with a vapor pressure above 124 kPa at 37,8 degrees Celsius must be tested according to ISO 6251 standard. Electrical insulation oils must be tested according to ISO 5662 standard.

Some products, particularly natural gasolines, can have a vapor pressure significantly higher than that characteristic of their class, even at 37,8 degrees Celsius (37.8 degrees Fahrenheit) and below 124 kPa. Therefore, extreme caution must be exercised to avoid placing a pressure vessel containing such material into a 100-degree bath. Such samples can develop sufficient pressure at 100 degrees Celsius to rupture the pressure vessel and cause damage or injury.

In principle, a polished copper strip is immersed in a sample of a specific volume and heated under temperature and time conditions specific to the material class being tested. Aviation fuels and natural gasolines are tested in a pressurized vessel, while other products are tested under atmospheric pressure. At the end of the heating period, the strip is removed, washed, and its color is evaluated according to corrosion standards.

The ISO 2160 standard defines a standardized method for evaluating the corrosiveness of liquid petroleum products (such as fuels, lubricants, and some solvents) to copper. Many petroleum products may contain trace amounts of sulfur compounds or other corrosive substances that can damage copper and copper alloy components in fuel systems, pipelines, storage tanks, and engines. Copper strip testing (copper corrosion testing) is a simple, qualitative method for detecting the presence of these active corrosive substances. It is widely used in the oil and gas industry for quality control, specification compliance, and product certification.

This test is technically very similar to, and generally considered equivalent to, the ASTM D130 standard.

The ISO 2160 standard applies to the following:

• Liquefied petroleum products (e.g., gasoline, diesel, jet fuel, heating oils, lubricants).
• Certain solvents.
• Volatile products with a maximum vapor pressure of 37,8 kPa (at 37,8 degrees). Products with higher vapor pressure require special procedures or pressure vessels.

This method is not applicable to primary liquefied petroleum gases (LPG) (a separate equivalent method applies to LPG).

During the test, a polished copper strip made of high-purity copper (typically 99,9%) is immersed in the petroleum product sample. The sample and strip are heated in a test tube or bomb for a specific time and temperature (common conditions depending on the product specification are 50 degrees for 3 hours or 100 degrees for 2-3 hours). After the test, the copper strip is removed, washed, and dried.

Color and surface appearance are visually compared to standard corrosion reference strips (typically a laminated card or a set of 5–6 reference strips showing gradual levels of darkening and corrosion).

The results are classified according to the degree of corrosion/tarnishing observed:

• 1a-1b: Slight darkening (such as light orange, dark orange): Generally acceptable for most applications.
• 2a-2e: Moderate darkening.
• 3a-3b: Deep darkening.
• 4a-4c: Corrosion (black, glossy black, or true pitting).

Many product specifications require a 1a or 1b (passed) result. A worse rating usually indicates the presence of active sulfur compounds and does not meet the specification.

The ISO 2160 standard plays a vital role in maintaining product reliability and safety:

• Prevents corrosion-related failures.
• Legal regulations support compliance.
• Ensures consistent fuel quality across markets.
• It protects metal components, especially copper alloys.

This standard is also considered important for the following reasons:

• Safety and reliability: Corrosive fuels can damage fuel pumps, injectors, copper pipes, and brass fittings.
• Quality control: Refineries, mixers, and dispersers use this testing to ensure products conform to international and national specifications (e.g., EN, ASTM, or original equipment manufacturer standards).
• Compliance with regulations: Many fuel and lubricant standards refer to the ISO 2160 standard.

Modern laboratories use automated or semi-automated copper corrosion testing equipment to increase repeatability.

The industrial applications of this standard are as follows:

• Automotive industry:
• It evaluates gasoline, diesel, and lubricants.
• Ensures compatibility with fuel injectors, pumps, and wiring systems.
• Aviation industry:
• This is critical for jet fuels, where even minor corrosion can affect safety.
• Petrochemical industry:
• It is used in quality control in refining and mixing processes.

In conclusion, the ISO 2160 standard is a fundamental quality test in the petroleum industry that helps ensure fuels and oils will not corrode copper-based materials in engines and distribution systems. It remains a simple yet effective pass/fail check trusted worldwide for product acceptance.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the ISO 2160 standard.