ISO 9227: How to conduct a salt spray test?

Standard:

ISO 9227: 2017

ISO 9227: 2017 Corrosion tests in artificial atmospheres - Salt spray tests

Equipment:

All salt spray chambers and corrosion chambers offered by Labomat Essor

1. Methodology

This methodology shall be used to perform the salt spray test standard according to ISO 9227-2017 in a corrosion chamber.

It should be used in conjunction with the ISO 9227-2017 standard document.

The test standard takes precedence over this method statement and this method may need to be changed to follow / conform to the standard.

This method is based on ISO 9227-2017:

Continuous exposure to salt spray at 35 ° C +/- 2 ° C with a salt concentration of 5% NaCl +/- 1%.

Three variants exist within the standard:

• NSS: Neutral Salt Spray (mixture of demineralized water and pure salt)
• AASS: Acetic Salt Spray (NSS solution + glacial acetic acid)
• CASS: Cupro Acetic Salt Spray (NSS solution + copper chloride dihydrate) at 50 ° C +/- 2 ° C

The chamber will be loaded with test samples as required by the customer, or according to ISO 9227-2017.

2. Instrumentation

All measuring equipment must be calibrated. The date of the renewal of the calibration should not coincide with the date of a test.

The corrosion enclosure should be calibrated for the air temperature of the chamber as a minimum. If required, the following chamber components can also be calibrated:

• Room air saturator temperature.
• Chamber air pressure gauge (atomizer pressure).

Corrosion chambers can be fitted with a relative humidity sensor. Calibration is not necessary as it is not used during salt spray testing.

Devices should also be calibrated before use and may include the following:

• Portable pH meter, it is calibrated using certified buffer solutions and following the manufacturer's instructions. The first solution pH 4.01 and the second solution pH 7.01. The acceptable tolerance is +/- 0.01. When complete, the electrode is rinsed using an electrode rinsing solution.
• Salinity refractometer, it is calibrated using a standard refractometer liquid solution. A salinity refractometer can give a direct reading of the percentage of sodium chloride in the range of 0 to 28%, with automatic temperature compensation.
• Conductivity meter, it is calibrated using standard solutions, it is used to check the conductivity of water and saline solution.

The temperature of the chamber can be continuously monitored if necessary, either using an independently calibrated data logger, or and depending on the model, the chamber has an Ethernet output to view and save this curve or has a internal recording.

For salt spray testing, it may be sufficient to manually read the chamber temperature daily manually using the chamber display on a tracking sheet.

For the measurement at the exposure of the saline solution, it is the pluviometry *, the collection rates are controlled manually using collection containers placed at the height of the sample. Collection rates should be in the range of 1 to 2 ml / h / 80 cm².

* Run a 24 hour cycle of the test with the empty chamber and collection funnels positioned, record the temperature and ensure it remains within a tolerance of 35 ° C +/- 2 ° C (50 ° C + / - 2 ° C for CASS). Make sure that the salt spray collection rates are within the expected range of 1-2 ml / h / 80 cm². Record all results. Check that the pH of the collected solution meets the requirements of the standard. Record all results. If necessary, adjust the pH of the salt solution in the solution tank to compensate for any change in pH once collected; so that the collected, the solution meets the requirements of the standard.

Exposure of saline is by atomization using compressed air. The air delivered to the spray nozzle should be `` heated and humidified '' by passing the air through an air saturator, the temperature of the air saturator in the chamber is adjusted according to the pressure at the atomizer pressure gauge. (See the table in ISO 9227-2017 for reference).

3. Preparation of the saline solution

Check that the conductivity of the water is measured and monitored and that it meets the requirements of the standard using a conductivity meter. (Less than 20 µS / cm at 25 ° C ± 2 ° C)

The concentration of the saline solution is measured and monitored and meets the requirements of the standard using a calibrated salinity refractometer. The pH of the saline solution is measured and monitored and meets the requirements of the standard using a calibrated pH meter.

NSS solution - neutral saline solution, after allowing the solution to stabilize for several hours, the salinity and the pH are measured and recorded. Any pH adjustment can be made using reagent grade hydrochloric acid (HCL) to increase acidity or regent grade sodium hydroxide (NaOH) or sodium bicarbonate (NA2CO3) to reduce acidity. acidity. Record all results.

AASS solution - Acetic Salt Spray, glacial acetic acid is added to the neutral saline solution so that the pH meets the required limits stipulated in the standard. Any pH adjustment can be made using glacial acetic acid to increase acidity or regent grade sodium hydroxide (NaOH) or sodium bicarbonate (NA2CO3) to reduce acidity. Record all results.

CASS solution - Copper chloride dihydrate (CuCl2 2H2O) is added to the neutral saline solution to give a concentration of 0.26 g / L (+/- 0.01 g / L) Any adjustment of the pH must be carried out using glacial acetic acid to increase acidity or regent grade sodium hydroxide (NaOH) or reactive grade sodium bicarbonate (NA2CO3) to reduce acidity. Save all results.

4. Preparation of samples

Test samples should be thoroughly cleaned before starting the test. This should not include the use of abrasives or solvents. This process must be agreed with the customer. Latex gloves should be worn at all times when handling samples. Photographs should be taken of each sample before starting the test.

5. Conduct of the test

This may require additional testing to prove results before you start testing with samples. It may be necessary to assess the corrosivity of the chamber before starting a test. Refer to the standard for more details.

Starting the test cycle

• Place the samples in the chamber according to the test standard.
• Set the temperature of the chamber air saturator according to the table in the test standard.
• Make sure that no sample is hiding other samples and that droplets from one sample cannot fall on other samples.
• Insert clean, empty salt spray collection vessels around the samples inside the chamber, preferably at the height of the sample, and never below the samples or any other object that may sink into them from above .
• Check that the room temperature is within acceptable limits.
• Check that the temperature of the air saturator is within acceptable limits.
• Check that the atomizer air pressure is within acceptable limits.
• Spray continuously with atomized saline solution at a constant chamber temperature of 35 ° C +/- 2 ° C (50 ° C +/- 2 ° C for CASS).
• Verify that the collected solution is within acceptable limits for fallout rates.
• Check that the saline solution in the tank is less than 5.0% + / -1.0% NaCl.
• Record the pH of the saline solution in the tank.
• Check that the pH of the collected saline solution is within acceptable limits.
• Exceptions to continuous testing are allowed, on the one hand to record daily fallout collection rates and the pH of the collected solution and on the other hand for daily verification.
• Record the conductivity of deionized water when it is in use.
• Monitor the level of saline in the tank and make sure there is enough for the next 24/48 hours. (Plan a supplement for weekends). NOTE, during the weekend, the opening time of the room must be minimal and not exceed 1 h / 24 h.
• Photographs to be taken before the start of the test and at times specified by the client.

Daily checks are necessary to ensure that the standard is being met with parameters varying within limits.

Save all settings.

The handling of the samples tested varies depending on their material.

Refer to the test standard and agree on the correct procedure with the customer.

Latex gloves should always be worn when handling specimens.

Photographs of the samples should be taken.

Recordings in and out of tolerance as well as downtimes and their duration should be noted in the test report, including details of any changes made.