Volvo STD 1027-1372 Accelerated Outdoor Exposure - Scab Corrosion Test

The standard “Volvo STD 1027-1372 Accelerated outdoor exposure - Scab corrosion test”, developed by the Volvo car company, describes a test method designed for use in corrosion testing of surface treatment systems. With this method, the corrosion process during outdoor exposure is accelerated by regularly spraying the test sample with a sodium chloride solution. The corrosion pattern is similar to that resulting from a salty environment.

However, changes in weather conditions may affect the result. Therefore, it is necessary to include a well-known reference material during exposure. Surface treatment systems and objects where the end-use location is not exposed to sunlight should be protected from direct sunlight during exposure.

Equipment and materials used in testing include:

• Test rack according to STD 5711,101 standard
• Spray bottle (garden sprayer) containing 5 percent (percent by mass) sodium chloride in distilled or deionized water. The quality of the sodium chloride should be according to STD 423-0010 standard.
• Test pieces:
  • Painted test panels (1021,5211 x 100 mm) of the substrate in question according to STD 200 standard
  • Surface treated components (parts)

Paint-coated test pieces are conditioned in accordance with STD 1021,1 standard.

Where relevant, chip tests are performed on test panels according to the STD 1024,7132 standard.

Painted test panels are scored through the paint films with a scribing tool. The scribing is done along the test panel, 70 mm from the short end of the test panel. The scribed line should be 80 mm long and 0,5 mm wide. It is important that the scribed line is done the same way each time the test is performed.

Where appropriate, the components are drawn. The location and extension of the drawn line are adapted to the design of the component. This is followed by outdoor exposure according to STD 5711,101. Here, the test specimens are sprayed twice a week with a 5 percent salt solution. In winter, the test specimens should be cleared of snow before spraying. The duration of the test is normally six months (unless otherwise stated). If a definitive result is not obtained, the duration of the test is extended by six-month intervals.

The test pieces are examined in accordance with:

• If a scratch is made, the spread of corrosion is checked. A distance of 15 mm from each end is not checked because damage may occur in this area and this will not result in a representative sample. In the 50 mm measuring section, the total spread of corrosion is shown in mm by subtracting the width of the drawn line along the drawn line. Any loss of adhesion, separate from or adjacent to the corrosion, is also noted. The result is given to an accuracy of 0,5 mm.
• Evaluation of general corrosion according to STD 5715,102 standard.
• If chip tests have been performed in these cases, the number of chips causing corrosion attack is given.

The test report to be prepared at the end of the test should indicate the following:

• Type and quality definition of test material
• Date of onset of outdoor exposure and geographic location
• Test duration
• Test result
• Tested according to STD 1027,1372 standard

Corrosion scale is the accumulation of corrosion product on the corroded area, forming a corrosion scale when external corrosion of carbon steel occurs. In this case, it is necessary to determine how much wall thickness remains under this scale in order to determine whether it is safe to operate the equipment. Scab corrosion testing is performed for this purpose.

If a section of pipe is encrusted, radiographic examination of the section can be performed to measure how much material remains. However, due to safety requirements, there are limitations to the strength of the radioactive source. Clear shots cannot be taken on pipes larger than 162 mm in diameter. Therefore, scab corrosion testing is required when encrusted on larger diameter pipes or vessels and tanks.

Among the numerous tests, measurements, analyses and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “Volvo STD 1027-1372 Accelerated outdoor exposure - Scab corrosion test” standard with its trained and expert staff and advanced technological equipment.