IS 3972 : Part 2 : Sec 3 : 2020/ISO 28706-2 : 2017 Methods of Test for Vitreous Enamelware - Part 2 Test Methods - Section 3 Resistance to boiling acids, boiling liquids, alkaline liquids and their vapours

Revised Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Part 2/Sec 3) (Second Revision), which is identical with ISO 28706-2 : 2017 ‘Vitreous and porcelain enamels — Determination of resistance to chemical corrosion — Part 2: Determination of resistance to chemical corrosion by boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation of the Ceramicware Sectional Committee and approval of the Chemical Division Council.

IS 3972 (Part 2/Sec 3) describes the method to determine the resistance of flat surfaces of vitreous and porcelain enamels to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours. This method allows the determination of the resistance of vitreous and porcelain enamels to the liquid and vapour phases of the corrosive medium simultaneously. For vitreous enamels fired at temperatures below 700°C, the test parameters (media, temperatures and times) of this standard are not appropriate. For such enamels, for example, aluminum enamels, other media, temperatures and/or times should be used. This can be done following the procedures described in the clause for ‘Other test solutions’.

Corrosion of vitreous and porcelain enamels by aqueous solutions is a dissolution process. The main component of the enamel, SiO2, forms a three-dimensional silica network. After hydrolysis, it decomposes and forms silicic acid or silicates. These are released into the attacking medium. Other components, mainly metaloxides, are hydrolysed as well and form the corresponding hydrated metal ions or hydroxides. The most important parameters influencing aqueous corrosion of the enamel are the enamel quality, the temperature and the pH value. Inhibition effects resulting from the limited solubility of silica can also contribute.

This standard was originally published in 1968 and subsequently revised in 1985. During the first revision, IS 3972 was bifurcated and part 2 of this standard was further divided into 13 sections, each dealing with various test methods applicable to vitreous enamelware. Part 2/Section 1 of IS 3972 had dealt with resistance of vitreous enamelware to citric acid at room temperature and boiling temperature, whereas Part 2/Section 3 of IS 3972 had dealt with resistance of vitreous enamelware to boiling water and water vapour. Furthermore, Part 2/Section 7 of IS 3972 had dealt with resistance of vitreous enamelware to boiling hydrochloric acid.

While reviewing sections 1, 3 and 7 of Part 2 of IS 3972, the committee decided to revise them by adopting ISO 28706-2 : 2017, thereby merging sections 1, 3 and 7. Method of test for determination of resistance to dilute citric acid at room temperature is prescribed by IS 3972 (Part 2/Sec 1) : 2020/ISO 28706-1 : 2008.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminologies and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker, while in Indian Standards, the current practice is to use a point (.) as the decimal marker.