IS 3972 : Part 2 : Sec 1 : 2020/ISO 28706-1 : 2008 Methods of Test for Vitreous Enamelware - Part 2 Test Methods - Section 1 Resistance to corrosion by dilute acids at room temperature

Revised Standard from Last Update.

NATIONAL FOREWORD

This Indian Standard (Part 2/Sec 1) (Second Revision) which is identical with ISO 28706-1 : 2008 ‘Vitreous and porcelain enamels —Determination of resistance to chemical corrosion — Part 1: Determination of resistance to chemical corrosion by acids at room temperature’ 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.

This section of part 2 of IS 3972 series of standards describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to chemical corrosion due to attack by dilute citric acid and dilute sulphuric acid at room temperature. It also prescribes a method of classifying the results.

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 metal oxides, 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. IS 3972 (Part 2/Sec 1) had dealt with resistance of vitreous enamelware to citric acid at room temperature and boiling temperature, whereas IS 3972 (Part 2/Sec 9) had dealt with resistance of vitreous enamelware to dilute sulphuric acid.

While reviewing IS 3972 (Part 2/Sec 1), the committee decided to revise it by adopting ISO 28706-1 : 2008 thereby merging section 9 with section 1. Method of test for determination of resistance to boiling citric acid is prescribed by IS 3972 (Part 2/Sec 3) : 2020/ISO 28706-2 : 2017.

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.