Overview
ISO 13807:2022 specifies a laboratory test method to determine the crack formation temperature of vitreous and porcelain enamels used in the chemical industry. The method subjects enamelled steel specimens to a controlled thermal shock - heating in an oven followed by immediate quenching with cold water - and identifies the temperature at which the first enamel cracks or chipping appear. The measured value is a comparative parameter for enamel formulations and does not directly represent the behavior of finished components (see Annex A).
Key topics and technical requirements
- Scope and purpose: Test for thermal shock resistance of enamel coatings on steel to determine crack formation temperature for comparing enamel quality.
- Definitions:
- Crack formation temperature: thermal shock temperature at which the first damage (cracks/chipping) occurs.
- Thermal shock temperature: specimen temperature immediately before quenching.
- Specimens:
- Typical specimen: square steel plate enamelled on one side (edge length 150 mm, thickness ≥ 10 mm) or 10MnTi3 low-alloy enamelling steel with specified nominal composition.
- Finished enamel coating thickness: overall 1.1 mm to 1.4 mm (measured per ISO 2178).
- Two specimens are used per determination.
- Apparatus:
- Drying oven capable of ≥ 300 °C.
- Low-form beaker (2 000 ml, ISO 3819 compliant) and a spray gun for electrostatically charged talcum powder to reveal fine cracks.
- Procedure summary:
- Heat specimen to the chosen thermal shock temperature in the oven (about 20 °C below expected crack temperature if known).
- Remove specimen and quench by pouring 2 L of water at 10 °C–30 °C onto the enamelled surface within 3 s of opening the oven.
- Dry, visually inspect and spray with charged talcum powder to detect cracks.
- If no damage, repeat the test at increments of +10 °C; average values within 10 °C are reported.
- Preconditioning: Controlled cooling after final firing-heat to 600 °C for ≥ 20 min then cool to 250 °C at ≤ 1 °C/min to reduce residual stresses.
- Reporting: Include enamel type, coating thickness, material code, individual crack temperatures (°C), mean value, and deviations from the procedure.
Applications and users
- Who uses it: Enamel manufacturers, coating labs, quality control engineers, product developers and procurement teams in the chemical process industry.
- Practical applications:
- Compare thermal shock resistance of different enamel formulations.
- Provide a repeatable lab parameter for R&D and QC of vitreous/porcelain enamels.
- Support material selection for equipment where enamel cracking under rapid cooling is a concern.
- Limitations: The test parameter is for comparing enamels under controlled lab conditions; it should not be used alone to predict finished-product resistance in service (see informative Annex A).
Related standards
Keywords: ISO 13807:2022, thermal shock testing, crack formation temperature, vitreous enamel, porcelain enamel, enamelled steel, chemical industry, enamel testing.
Open preview (PDF)Vitreous and porcelain enamels — Determination of crack formation temperature in the thermal shock testing of enamels for the chemical industry