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GB/T 223.69-2008 English PDF (GBT223.69-2008)

GB/T 223.69-2008 English PDF (GBT223.69-2008)

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GB/T 223.69-2008: Iron, steel and alloy -- Determination of carbon contents -- Gas-volumetric method after combustion in the pipe furnace

This Part of GB/T 223 specifies a gas-volumetric method after combustion in the pipe furnace for the determination of the carbon content. This Part applies to the determination of the carbon content with the mass fraction of 0.10 % ~ 2.00 % in steel, iron, high temperature alloys and precision alloys.
GB/T 223.69-2008
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.080.01
H 11
Replacing GB/T 223.69-1997
Iron, steel and alloy - Determination of carbon
contents - Gas-volumetric method after
combustion in the pipe furnace
ISSUED ON. MAY 13, 2008
IMPLEMENTED ON. NOVEMBER 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the PEOPLE Republic of China;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Principle ... 5
4 Reagents and materials ... 5
5 Instruments and equipment ... 6
6 Sampling ... 8
7 Analysis procedure ... 9
8 Calculation of results ... 10
9 Precision ... 12
10 Test report ... 12
Annex A (informative) Correction factor of temperature and pressure ... 14 Annex B (informative) Additional information for precision joint test... 42 Foreword
This Part of GB/T 223 replaces GB/T 223.69-1997 ?€?Methods for chemical analysis of iron, steel and alloy - The gas-volumetric method after combustion in the pipe furnace for the determination of carbon content?€?.
Compared with GB/T 223.69-1997, main modifications of this Part are as follows. - MODIFY the name to ?€?Iron, steel and alloy - Determination of carbon contents - Gas-volumetric method after combustion in the pipe furnace?€?.
- MODIFY the equations for calculation of results and the units of the amount in the equations;
- NORMALIZE the description of the precision function.
Annexes A and B of this Part are informative annexes.
This Part is proposed by China Iron and Steel Association.
This Part is under the jurisdiction of National Technical Committee on Iron and Steel of Standardization Administration of China.
Drafting organization of this Part. China Iron and Steel Research Institute Group. Main drafters of this Part. Cui Qiuhong, Wang Yuxing.
The historical editions of the standard replaced by this Part are as follows. GB 223.69-1989, GB/T 223.69-1997.
Iron, steel and alloy - Determination of carbon
contents - Gas-volumetric method after
combustion in the pipe furnace
Warning. Personnel using this Part shall have practical experience in formal laboratory work. This Part does not indicate all possible security issues. It is the user's responsibility to take appropriate safety and health measures and to ensure compliance with the requirements of the relevant state laws and
regulations.
1 Scope
This Part of GB/T 223 specifies a gas-volumetric method after combustion in the pipe furnace for the determination of the carbon content.
This Part applies to the determination of the carbon content with the mass fraction of 0.10 % ~ 2.00 % in steel, iron, high temperature alloys and precision alloys. 2 Normative references
The following standards contain provisions which, through reference in this Part of GB/T 223, constitute provisions of this Part. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this Part are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 6379.1 Accuracy (trueness and precision) of measurement methods and results - Part 1. General principles and definitions
GB/T 6379.2 Accuracy (trueness and precision) of measurement methods and results - Part 2. Basic method for the determination of repeatability and reproducibility of a standard measurement method
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
3 Principle
The sample and flux are combusted in the high temperature (1 200 ??C ~ 1 350 ??C) pipe furnace with oxygen introduced, and the carbon is completely oxidized to carbon dioxide. After removing the sulfur dioxide, collect the gas mixture in the gas burette, and measure the volume. Use potassium hydroxide solution to absorb carbon dioxide, and then measure the volume of the remaining gas. The difference between the volume of gas before and after absorption is the volume of carbon dioxide, which is used to calculate the carbon content.
4 Reagents and materials
4.1 Oxygen, with the purity of not less than 99.5 % (volume fraction).
If oxygen is suspected of containing organic impurities, an oxidizing catalyst [copper oxide (II) or platinum] pipe heated to the temperature of above 45 ??C shall be added before using the oxygen purification device.
4.2 Solvent, applicable to washing the oil or dirt on the surface of the sample, such as acetone.
4.3 Active manganese dioxide (or silver vanadate), granular.
When there is not suitable chemically active grade manganese dioxide, it can be prepared as follows.
To prepare about 50 g of active manganese dioxide, DISSOLVE 200 g of manganese tetra-sulfate manganese sulfate (MnSO4 ?€? 4H2O) in 2.5 L of water in a 4 L beaker, ADJUST it to alkaline with ammonia (?? is about 0.90 g/mL), ADD 1 L of freshly prepared ammonium persulfate solution (225 g/L), HEAT the solution to boil and keep boiling for another 10 min. During the heating and boiling, in order to keep the solution being ammoniac, ammonia shall be continuously added to settle the precipitate. If the supernatant does not clear or precipitate does not settle quickly, it may add 50 mL ~ 100 mL of ammonium persulfate solution (225 g/L), boil for 10 min and keep the solution always being ammoniac. ALLOW the solution to stand for some time so that the manganese dioxide is completely precipitated. SIPHON the supernatant carefully and WASH the precipitate with 3 L or 4 L of warm water at 500 mL to 600 mL each using decantation method. After each wash and before decantation, fully stir the manganese dioxide in water to make it settle. Finally, wash with dilute sulfuric acid solution [add 2 drops of sulfuric acid per 1 000 mL of solution (?? is 1.84 g/mL)] twice in the same manner.
During this period, PREPARE a funnel with the diameter of 15 cm, TAKE a filter plate with the diameter of 5 cm and PLACE it on the funnel, and COVER the filter plate with a thin layer of purified asbestos pulp (it may also use a Brinell porcelain funnel instead of a filter plate). After the last wash, TRANSFER the manganese dioxide to the filter, RINSE it with warm water until it is free of sulfate ions, and PLACE it on a porcelain plate and DRY in an oven at 105 ??C. Finely GROUND the manganese dioxide in a mortar so that it passes through a sieve with the diameter of 0.8 mm, and then sufficiently DRY at 105 ??C.
4.4 Potassium permanganate - potassium hydroxide solution, WEIGH 30 g of potassium hydroxide and DISSOLVE in 70 mL of potassium permanganate saturated solution.
4.5 Sulfuric acid blocking solution, ADD 1 mL of sulfuric acid (?? is about 1.84 g/mL) to 1 000 mL of water, and ADD a few drops of methyl orange solution (1 g/L) until there is a stable light red.
4.6 Sodium chloride blocking solution, WEIGH 26 g of sodium chloride and DISSOLVE in 74 mL of water, ADD a few drops of methyl orange solution (1 g/L), ADD sulfuric acid (1 + 2) dropwise until there is a stable light red.
4.7 Flux, granular tin, copper, copper oxide, vanadium pentoxide, iron powder. The carbon content of each flux shall generally not exceed 0.005 0 % by mass. The blank test shall be carried out before use, and the blank value shall be deducted from the measured value of the sample.
4.8 Glass wool.
5 Instruments and equipment
In analysis, except for the following provisions, only ordinary laboratory instruments and equipment are used.
Instruments and equipment installation are shown in Figure 1.
1 - oxygen bottle;
2 - partial pressure gauge (with flow meter and buffer valve);
3 - buffer bottle;
4 - gas washing bottle I;
5 - gas washing bottle II;
6 - drying tower;
7 - oxygen supply piston;
8 - glass ground stopper;
9 - pipe furnace;
10 - temperature controller (or pressure regulator).
11 - spherical drying pipe;
12 - desulfurizing pipe;
13 - capacity carbon detector (including serpentine pipe a, gas burette b, levelling bottle c, absorber d, small piston e, three-way piston f).
14 - porcelain pipe;
15 - porcelain boat.
Figure 1 -- Diagram of instrument and equipment
5.1 Oxygen purification device
5.1.1 Buffer bottle (see Figure 1)
5.1.2 Gas washing bottle I (see Figure 1), containing potassium permanganate - potassium hydroxide solution (4.4), and the amount of the solution loading is about a third of the volume of the gas washing bottle I.
5.1.3 Gas washing bottle II (see Figure 1), containing sulfuric acid (?? about 1.84 g/mL). and the amount of sulfuric acid loading is about one third of the volume of the gas washing bottle II.
5.1.4 Drying tower (see Figure 1), containing asbestos (or soda lime) on the upper layer, and anhydrous calcium chloride on the lower layer, separated with glass wool (4.8) in the middle; the bottom and the top are also covered with glass wool. 5.2 Pipe furnace (see Figure 1)
With thermocouple and temperature controller. High-temperature heating equipment can also be high-frequency heating device.
5.3 Porcelain pipe (see Figure 1)
The porcelain pipe is of 600 mm length and 23 mm diameter (porcelain pipes of similar specifications can also be used). The thick end of the porcelain pipe is connected to the glass ground stopper, and the conical end is connected to the spherical drying pipe by a rubber pipe. Check whether it leaks before use, and then burn. The rubber stopper for the connection between the porcelain pipe and the oxygen purification device (5.1), the drying pipe, and the desulfurizing ...

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