Overview
SIST ISO 28706-2:2021 specifies a standardized test method to determine the resistance of flat surfaces of vitreous and porcelain enamels to chemical corrosion by boiling media. The method covers exposure to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours, and allows simultaneous assessment of attack by both the liquid and vapour phases of the corrosive medium. This second edition extends the scope to include alkaline liquids and a standard detergent solution.
Key topics and technical requirements
- Scope and specimen: Applies to flat enamel surfaces; describes required test specimens and preparation.
- Test principle: Simulates corrosion by boiling solutions and/or condensate vapour to evaluate enamel dissolution and surface degradation.
- Reagents and test solutions: Includes boiling citric acid, sulfuric acid, hydrochloric acid, distilled/demineralized water, standard detergent, and provisions for other solutions/conditions.
- Apparatus and packing: Details test apparatus, materials and packing ring types (Packing A and B) to control liquid/vapour exposure.
- Procedure: Specifies exposure conditions (temperature, duration, solution composition) and handling to ensure reproducible results.
- Expression of results: Results are reported as total loss in mass per unit area (g/m²) for tests that show logarithmic behavior, and as rate of loss in mass per unit area (g/m²·h) and corrosion rate (mm/year) where attack proceeds linearly (for example, azeotropic boiling acids).
- Corrosion behavior considerations: Discusses how enamel composition, temperature, pH and silica solubility influence attack; explains inhibition effects in liquid-phase testing and why vapour-phase condensate can give uninhibited attack.
Practical applications and users
This standard is valuable for:
- Enamel manufacturers and quality-control laboratories assessing product durability.
- Coating and materials engineers specifying enamel systems for corrosive environments.
- Corrosion testing laboratories performing standardized comparative tests.
- Procurement and compliance teams who require accredited test data for specification and acceptance.
Typical application areas include sanitaryware, cookware and appliances, chemical process equipment and other products where vitreous/porcelain enamel is used to provide corrosion resistance and inert surfaces.
Related standards
- ISO 28706 series (other parts cover room-temperature tests, autoclave/pressurized testing and specific solutions).
- ISO 28706-1 and ISO 28706-5 are referenced within the document for complementary test conditions and interpretation.
Keywords: SIST ISO 28706-2:2021, vitreous enamel, porcelain enamel, chemical corrosion resistance, boiling acids test, corrosion rate, mass loss per unit area, vapor-phase testing, enamel corrosion testing.