GB/T Translated English of Chinese Standard: GB/T

Transcription

1 Translated English of Chinese Standard: GB/T GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA ICS H 11 GB/T Replacing GB/T Methods for Chemical Analysis of Iron, Steel and Alloy The Potassium Iodate Titration Method after Combustion in the Pipe Furnace for the Determination of Sulfur Content GB/T How to BUY & immediately GET a full-copy of this standard? Search --> Add to Cart --> Checkout (3-steps); 3. No action is required - Full-copy of this standard will be automatically & immediately delivered to your address in 0~60 minutes. 4. Support: Sales@ChineseStandard.net. Wayne, Sales manager Issued on: March 17, 1997 Implemented on: September 1, 1997 Issued by: State Bureau of Technical Supervision of the People s Republic of China Page 1 of 15

2 Table of Contents Foreword Application Scope Normative References Method Summary Reagents and Materials Apparatus Sampling and Sample Preparation Analytical Procedures Analytical Result and Its Expression Precision Test Report Annex A (Normative) Samples for Precision Test of the Potassium Iodate Titration Method after Combustion in the Pipe Furnace Annex B (Informative) Raw Data of Precision Test of the Potassium Iodate Titration Method after Combustion in the Pipe Furnace Page 2 of 15

3 Foreword This Standard was drafted by revising GB , Methods for Chemical Analysis of Iron Steel and Alloy the Combustion Potassium Iodate Volumetric Method for the Determination of Sulfur Content, in accordance with the national standard of the People s Republic of China GB/T , Directives for the Work of Standardization Unit 1: Drafting and Presentation of Standards Part 1: General Rules for Drafting Standards, and GB , Directives for the Work of Standardization, Rules for Drafting Chemical Analysis Methods. In accordance with 4.2 and of Article 4 of GB/T and 6.10 of Article 6 of GB , Foreword, Normative References of Article 2, Sampling and Sample Preparation of Article 6 and Test Report of Article 10 are added in this revision, and meanwhile, the high sulfur absorption sample cell is deleted, only the low sulfur absorption sample cell is kept as the absorption sample cell. Annex A and Annex B of this Standard are informative annexes. From the effective date of this Standard, this Standard replaces GB This Standard was proposed by the Ministry of Metallurgical Industry of the People s Republic of China. This Standard shall be under the jurisdiction of the National Standardization Technical Committee on Steels. This Standard was drafted by Shanghai No. 1 Iron and Steel Co., Ltd. and Ministry of Metallurgical Industry Central Iron and Steel Research Institute. The main drafters of this Standard: Xu Mingliang, Cui Qiuhong, Wang Yuxing. This Standard was issued for the first time in the name of GB (II)-81 in 1981; and it was revised in the name of GB in 1989, in which the precision of method was decided. Page 3 of 15

4 Methods for Chemical Analysis of Iron, Steel and Alloy The Potassium Iodate Titration Method after Combustion in the Pipe Furnace for the Determination of Sulfur Content 1 Application Scope This Standard specifies the potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content. This Standard applies to the determination of sulfur content of % (m/m) ~ 0.20% (m/m) in iron, steel, high temperature alloy and precision alloy. 2 Normative References The provisions in following documents become the provisions of this Standard through reference in this Standard. All editions shown are effective when this Standard is issued. All standards will be revised, however, parties who reach an agreement based on this Standard are encouraged to study if the latest versions of the following standards are applicable. GB , Method of Sampling Steel for Determination of Chemical Composition and Permissible Variations for Product Analysis GB , Precision of Test Methods Determination of Repeatability and Reproducibility for a Standard Test Method by Interlaboratory Tests 3 Method Summary Test sample and combustion-supporting agent burn in a pipe furnace at high temperature (1 250 C ~ C) by pumping in oxygen; sulfur is fully oxidized into sulfur dioxide; and then use acidic starch solution to absorb and use potassium iodate standard solution for titration. Calculate the content of sulfur in accordance with the volume of potassium iodate consumed. 4 Reagents and Materials 4.1 Oxygen of purity not lower than 99.5% (m/m). Page 4 of 15

5 If the content of organic impurities in oxygen is suspected, add one oxidation catalyst [copper oxide (II) or platinum] pipe heated to the temperature over 450 C for treatment before the purification equipment (5.1). 4.2 Solvents which are applicable to wash the grease or dirt on the surface of samples, such as acetone. 4.3 Anhydrous calcium chloride (solid). 4.4 Potassium iodide (solid). 4.5 Soda asbestos. 4.6 Sulphuric acid (ρ 1.84 g/ml). 4.7 Hydrochloric acid (ρ 1.19 g/ml). 4.8 Potassium hydroxide (100 g/l). 4.9 Cosolvent Iron powder Vanadium pentoxide. Place in a furnace of high temperature 600 C to burn for 2 h ~ 3 h in advance, and place in a ground-glass stoppered flask as standby after cooling Stannic oxide. Screen out stannic oxide of grain size mm to place in a big porcelain boat, pump in oxygen to burn in a pipe furnace for 2 min at C, and place in a ground-glass stoppered flask as standby after cooling Starch absorption liquid. Weigh 10 g of soluble starch (sweet potato starch), use a small amount of water to make into it into a paste, add 500 ml of boiling water, stir, heat to boiling before taking down, add 500 ml of water and 2 drops of hydrochloric acid (ρ 1.19 g/ml) before stirring up and allowing to stand, take 25 ml of supernatant liquid for use, add 15 ml of hydrochloric acid (ρ 1.19 g/ml) and use water to dilute to ml before mixing up Potassium iodate standard solution Potassium iodate standard solution [c( 1 6 KIO 3) = 0.01 mol/l] Weigh g (accurate to ± 0.1 mg) of potassium iodate (standard reagent) to dissolve in water, add 1 ml of potassium hydroxide solution (100 g/l), transfer to a ml volumetric flask, and use water to dilute to the scale before mixing up Potassium iodate standard solution [c( 1 6 KIO 3) = mol/l] Page 5 of 15

6 6 Sampling and Sample Preparation Take or prepare samples in accordance with GB 222 or an applicable national standard for iron. 7 Analytical Procedures Safety instructions: for combustion analysis, the risks mainly come from the precombustion of the porcelain boat and the burns during fusion. The porcelain boat shall only be carried using tweezers and contained in an appropriate container at any time of the analysis. Normal protective measures shall be taken for operating steel cylinders containing oxygen. The existence of high-concentration oxygen in a narrow space may cause fires, so the oxygen existing in the combustion process shall be discharged effectively from the equipment. 7.1 Mount the porcelain tube, switch on the power supply and raise the temperature. For the samples of iron, carbon steel and low alloy steel, raise the temperature to C ~ C; and for medium- and high-alloy steel, high-temperature alloy and precision alloy, raise the temperature to over C. 7.2 Pump in oxygen, adjust its flow rate to ml/min ~ ml/min, check whether the pipeline and piston of the whole equipment leaks, regulate and maintain the equipment in the normal working status. After replacing sulphuric acid in the gaswashing bottle and the degreasing cotton in the spherical drying tube and replacing porcelain tube, first burn several non-standard samples and then start analytical operation after saturating the system using sulphur dioxide. 7.3 Blank test Carry out blank test repeatedly for the porcelain boat, porcelain cover and fluxing agent without adding the test material until the value of the blank test becomes stabilized, and the blank test shall be carried out frequently during the measurement of samples to obtain the stabilized value (V 0 ). 7.4 Choose an appropriate standard sample to carry out measurement in accordance with the analytical procedures 7.5 ~ to check the equipment. Only after the equipment is as required, the analysis of samples may be started. 7.5 Mass of test sample Use an appropriate amount of solvent (4.2) to wash the grease or dirt on the surface of test samples. Remove the residual washing solution by heating and evaporation. Weigh the mass of test samples as specified in Table 1. Page 9 of 15