What is the ISO 8502-6 standard?
The ISO 8502-6 standard is a part of the ISO 8502 series, which specifies tests for the assessment of surface cleanliness of steel substrates before application of paints and related products. The ISO 8502-6 standard specifies a method of extracting, for analysis, water soluble contaminants from a surface by use of flexible cells in the form of adhesive patches or sleeves which can be attached to any surface, regardless of its shape (flat or curved) and its orientation (facing in any direction, including downwards). The method described is suitable for use in the field to determine the presence of water soluble contaminants before painting or a similar treatment. What are water soluble contaminants and why are they harmful?
Water soluble contaminants are substances that can dissolve in water and cause corrosion or adhesion problems for coatings. They include salts (such as chlorides, sulfates, and nitrates), acids, alkalis, and other organic or inorganic compounds. Water soluble contaminants are often invisible to the naked eye and can be present on steel surfaces due to environmental exposure, blast cleaning media, or previous coatings. If left on the surface, they can attract moisture through the coating and create an electrolytic cell that causes corrosion or blistering. This can result in premature coating failure and high re-coating and maintenance costs. How does the ISO 8502-6 standard help prevent coating failures?
The ISO 8502-6 standard helps prevent coating failures by providing a reliable and standardized method of measuring the amount of water soluble contaminants on a surface. By following this method, one can ensure that the surface is sufficiently clean and free of harmful contaminants before applying a coating. The ISO 8502-6 standard also provides guidance on how to analyze the extracted solution for different types of contaminants using other parts of the ISO 8502 series or other suitable methods. By knowing the type and concentration of contaminants on a surface, one can choose the appropriate coating system and application conditions to achieve optimal performance and durability. How does the ISO 8502-6 standard compare with other methods?
The ISO 8502-6 standard is also known as the Bresle method, which was developed in France in the 1990s and adopted by ISO in 1995. The Bresle method is widely accepted and used by various organizations and industries, such as the US Navy, IMO, NAVSEA, ASTM, SSPC, NACE, and others. The Bresle method has several advantages over other methods of measuring soluble salt contamination, such as: - It can be applied to any surface shape or orientation - It does not require expensive or complex equipment - It is easy to perform and interpret - It has a high sensitivity and accuracy - It can measure different types of contaminants However, the Bresle method also has some limitations, such as: - It may not detect all soluble materials on a surface due to crevices, folds, corrosion layers, or thin films - It may not be suitable for very rough or porous surfaces - It may introduce contamination from the patches or solvents if not properly handled - It may require additional analysis for specific contaminants Therefore, it is important to follow the ISO 8502-6 standard carefully and use certified patches and solvents to ensure reliable results. It is also advisable to compare the results with other methods or standards if available. What equipment do you need for the ISO 8502-6 standard?
The equipment you need for the ISO 8502-6 standard are: Flexible cells
Flexible cells are devices that create a sealed chamber on a surface to hold a solvent for extraction. They can be either adhesive patches or sleeves that are attached to the surface with an adhesive ring. The flexible cells should have a known internal volume (usually between 1 ml and 5 ml) and an opening for injecting or withdrawing the solvent. The flexible cells should also be certified according to Annex A of the ISO 8502-6 standard for leak testing. Solvent
The solvent used for extraction should be water that meets the requirements of grade 3 of ISO 3696:1987 or equivalent. The solvent should be free of contaminants that could interfere with the analysis or affect the results. The solvent should also be stored in clean and sealed containers to prevent contamination or evaporation. Syringe
The syringe is used to inject and withdraw the solvent from the flexible cells. It should have a capacity of at least 10 ml and a graduation of 0.1 ml or better. The syringe should also have a needle or a nozzle that fits the opening of the flexible cells. The syringe should be clean and dry before use and rinsed with solvent after each extraction. Conductivity meter
The conductivity meter is used to measure the electrical conductivity of the extracted solution, which is proportional to the amount of soluble salts present. The conductivity meter should have a range of at least 0 to 200 µS/cm and an accuracy of 2% or better. The conductivity meter should also have a temperature compensation function or a separate thermometer to correct for the effect of temperature on conductivity. The conductivity meter should be calibrated before use with standard solutions of known conductivity according to the manufacturer's instructions. Other equipment
Other equipment that may be needed for the ISO 8502-6 standard are: - A timer or a stopwatch to measure the extraction time - A balance or a scale to measure the mass of the flexible cells before and after extraction - A calculator or a spreadsheet to perform calculations and conversions - A notebook or a record sheet to document the results and observations - A magnifying glass or a microscope to inspect the surface for contamination - A brush or a cloth to clean the surface before extraction - A pair of scissors or a cutter to cut the flexible cells if needed - A pair of gloves and safety glasses to protect yourself from the solvent and contaminants How do you perform the ISO 8502-6 standard?
The procedure for performing the ISO 8502-6 standard is as follows: Step 1: Prepare the surface
Before applying the flexible cells, you should inspect and clean the surface to remove any loose dust, dirt, grease, oil, or other contaminants that could affect the extraction. You can use a brush, a cloth, or an appropriate solvent to wipe the surface gently. You should also mark the area where you want to apply the flexible cells with a pencil or a tape. The area should be representative of the surface condition and large enough to accommodate the flexible cells. Step 2: Apply the flexible cells
Next, you should apply the flexible cells to the surface according to Annex B of the ISO 8502-6 standard. You can use either adhesive patches or sleeves depending on the shape and orientation of the surface. You should peel off the protective film from the adhesive ring and press it firmly onto the surface, making sure there are no air bubbles or wrinkles in between. You should also record the mass of each flexible cell before applying it using a balance or a scale. Step 3: Inject and withdraw the solvent
Then, you should inject and withdraw the solvent from each flexible cell using a syringe according to Annex C of the ISO 8502-6 standard. You should fill the syringe with solvent and insert it into the opening of the flexible cell, making sure there is no leakage or spillage. You should inject enough solvent to fill about half of the volume of the flexible cell and wait for at least 10 minutes for extraction. You should then withdraw all of the solvent from each flexible cell using the same syringe and transfer it into a clean and labeled container for analysis. You should also record the mass of each flexible cell after extraction using a balance or a scale. Step 4: Measure and analyze the extracted solution
Finally, you should measure and analyze the extracted solution using a conductivity meter according to Annex D of the ISO 8502-6 standard. You should rinse the conductivity meter with solvent before and after each measurement and calibrate it with standard solutions of known conductivity. You should measure the conductivity of each extracted solution and record the value in µS/cm. You should also calculate the surface density of soluble salts for each flexible cell using the formula: $$S = \fracC \times VA$$ where S is the surface density of soluble salts in mg/m, C is the conductivity of the extracted solution in µS/cm, V is the volume of the flexible cell in ml, and A is the area of the flexible cell in cm. You should report the average surface density of soluble salts for all flexible cells applied to the same area. Step 5: Interpret and compare the results
After measuring and analyzing the extracted solution, you should interpret and compare the results with the specifications or requirements for your coating project. Different coating systems and applications may have different acceptable levels of soluble salt contamination on a surface. For example, according to ISO 12944-4:2018, the maximum permissible surface density of soluble salts for carbon steel substrates before painting is 50 mg/m for C3 to C5 environments and 20 mg/m for CX environments. You should check with your coating manufacturer or supplier for the recommended values for your specific coating system and application. If your results exceed the acceptable levels, you may need to repeat the extraction procedure or perform additional surface preparation methods to reduce the contamination. Conclusion
The ISO 8502-6 standard is a useful and reliable method of measuring water soluble contaminants on steel surfaces before coating. It can help prevent coating failures caused by corrosion or adhesion problems due to soluble salt contamination. It can also help you choose the appropriate coating system and application conditions for optimal performance and durability. By following the ISO 8502-6 standard, you can ensure that your surface is sufficiently clean and free of harmful contaminants before applying a coating. FAQs
What is ISO 8502-6?
ISO 8502-6 is a standard that specifies a method of extracting water soluble contaminants from a surface by use of flexible cells. Why is ISO 8502-6 important?
ISO 8502-6 is important because it helps prevent coating failures caused by corrosion or adhesion problems due to soluble salt contamination. How do I perform ISO 8502-6?
You can perform ISO 8502-6 by applying flexible cells to the surface, injecting and withdrawing solvent from them, measuring and analyzing the extracted solution, and interpreting and comparing the results. What equipment do I need for ISO 8502-6?
You need flexible cells, solvent, syringe, conductivity meter, and other equipment for ISO 8502-6. Where can I download ISO 8502-6 PDF for free?
You can download ISO 8502-6 PDF for free from [this link].
iso 8502-6 pdf free download
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