This Standard specifies principle, test solution, samples, test procedure, result calculation, reproducibility and of test methods for gravimetric determination of the mass per unit area of galvanized coatings on steel products.
The stated galvanized coatings in this Standard includes pure galvanizing coating as well as zinc-iron alloy and allumen coating (such as zinc -5% aluminum alloy coating and 55% aluminum-zinc alloy coating) This Standard is applicable to steel products such as hot dip galvanizing and electro-galvanizing which are easy for the determination.
Methods in Appendix A also may be adopted for the mass test for the zinc coating of galvanized steel sheets.
2 Normative References
The following standards contain provisions which, through reference in this Standard, constitute provisions of this Standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document applies.
GB/T 8170 Rules for Rounding off of Numerical Values
3 Principle
Galvanized coatings on the already known surface area are dissolved in the test solution with inhibition of corrosion and then sample mass before and after coatings are dissolved is weighed; finally mass of galvanized coatings per unit area is calculated according to the weighing difference and sample area.
4 Test Solution
4.1 Cleaning fluid
Chemically pure absolute alcohol.
4.2 Test solution
4.2.1 3.5g chemically pure hexamethylene tetramine (C6H12N4) is dissolved in 500mL concentrated hydrochloric acid (ρ=1.19g/mL) and then distilled water or deionizer water is adopted to dilute it to 1000mL.
4.2.2 If the test solution may be able to dissolve galvanized coatings, it may be used repeatedly.
5 Samples
5.1 Sampling position and quantity shall be implemented according to the requirements of product standard and mutual agreement.
5.2 Test surface shall be selected according to the thickness of coatings to ensure samples to meet requirements on weighing accuracy.
5.3 Attention shall be paid to avoid surface damage in cutting off samples and samples with partial visible damage shall not be used.
5.4 Samples of steel plates and steel strips may be round or square and single-side area for arbitration test shall be 3000mm2-5000mm2.
5.5 Length of wire samples shall be cut off according to those specified in Table 1.
