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GB/T 223.71-1997 PDF in English


GB/T 223.71-1997 (GB/T223.71-1997, GBT 223.71-1997, GBT223.71-1997)
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GB/T 223.71-1997: PDF in English (GBT 223.71-1997)

GB/T 223.71-1997
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.080
H 11
Replacing GB/T 223.71-1991
Methods for Chemical Analysis of Iron, Steel and Alloy
The Gravimetric Method after Combustion in the Pipe
Furnace for the Determination of Carbon Content
ISSUED ON. MARCH 17, 1997
IMPLEMENTED ON. SEPTEMBER 1, 1997
Issued by. State Bureau of Technical Supervision of the People’s
Republic of China
Table of Contents
Foreword ... 3 
1 Application Scope ... 4 
2 Normative References ... 4 
3 Method Summary ... 4 
4 Reagents and Materials ... 4 
5 Apparatus ... 6 
6 Sampling and Sample Preparation ... 8 
7 Analytical Procedures ... 8 
8 Analytical Result and Its Expression ... 11 
9 Precision ... 11 
10 Test Report ... 12 
Annex A (Informative) Samples for Precision Test of the Gravimetric Method
after Combustion in the Pipe Furnace ... 13 
Annex B (Informative) Raw Data of Precision Test of the Gravimetric Method
after Combustion in the Pipe Furnace ... 14 
Foreword
This Standard was drafted by revising GB 223.71-91, Methods for Chemical Analysis
of Iron Steel and Alloy – the Combustion Gravimetric Method for the Determination of
Carbon Content, in accordance with the national standard of the People’s Republic of
China, GB/T 1.1-1993, Directives for the Work of Standardization – Unit 1. Drafting
and Presentation of Standards – Part 1. General Rules for Drafting Standards, and GB
1.4-88, Directives for the Work of Standardization – Rules for Drafting Chemical
Analysis Methods.
In accordance with 4.2.3 and 4.3.3 of Article 4 of GB/T 1.1-1993 and 6.10 of Article 6
of GB 1.4-88, “Foreword”, “Normative References” of Article 2, “Sampling and Sample
Preparation” of Article 6 and “Test Report” of Article 10 are added in this revision.
Annex A and Annex B of this Standard are informative.
As from the effective date of this Standard, this Standard replaces GB 223.71-91.
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 Metallurgical Equipment Factory and Ministry
of Metallurgical Industry Central Iron and Steel Research Institute.
The main drafters of this Standard. Jin Shenghui, Wang Yuxing, Guo Xiang, Cui
Qiuhong.
This Standard was issued for the first time in the name of GB 223.1 (1)-81 in 1981;
and it was revised in the name of GB 223.71-91 in 1991, in which the precision of
method was decided.
Methods for Chemical Analysis of Iron, Steel and Alloy
The Gravimetric Method after Combustion in the Pipe
Furnace for the Determination of Sulfur Content
1 Application Scope
This Standard specifies the gravimetric method after combustion in the pipe furnace
for the determination of sulfur content.
This Standard applies to the determination of carbon content of 0.10% (m/m) ~ 5.00%
(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 222-84, Method of Sampling Steel for Determination of Chemical Composition
and Permissible Variations for Product Analysis
GB 6379-86, Precision of Test Methods – Determination of Repeatability and
Reproducibility for a Standard Test Method by Interlaboratory Tests
3 Method Summary
Test sample and fluxing agent burn in a pipe furnace at high temperature (1 250°C ~
1 350°C) by pumping in oxygen; carbon is fully oxidized into carbon dioxide. After
removing sulphur dioxide, use the soda asbestos absorption flask of a known mass to
absorb the carbon dioxide in the mixed gas. Weigh the increment of the absorption
flask and calculated the carbon content of test sample based on the increment.
4 Reagents and Materials
4.1 Oxygen of purity not lower than 99.5% (m/m).
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 Solvent which is applicable to washing the grease or dirt on the surface of
samples, such as acetone.
4.3 Magnesium perchlorate [Mg(ClO4)] of grain size 0.7 mm ~ 1.2 mm.
4.4 Fluxing agents, such as granular tin, copper wire, copper oxide, iron powder and
vanadium pentoxide, whose carbon content shall be less than 0.002% (m/m).
4.5 Active manganese dioxide, which is granular.
If there is no active manganese dioxide of appropriate grade, it may be prepared in
accordance with the following method.
In order to prepare about 50 g of active manganese dioxide, dissolve 200 g of
manganese sulfate tetrahydrate (MnSO4·4H2O) to 2.5 L of water in a 4-L beaker, use
ammonium hydroxide (ρ 0.90 g/mL) to adjust to alkalinity, add 1 L of a newly-prepared
ammonium persulfate solution (225 g/L), heat the solution to boiling, continue boiling
for 10 min, and constantly add ammonium hydroxide to keep the ammoniacal nature
of the solution during the heating and boiling period and to make the precipitations fall.
If the supernatant liquid is not clear or the precipitation does not fall rapidly, add 50 mL
~ 100 mL of the ammonium persulfate solution (225 g/L) more, boil for 10 min and
keep the solution ammoniacal from beginning to end. Store the solution for a certain
time, let manganese dioxide fully precipitate, siphon the supernatant liquid carefully,
use 3 L or 4 L of warm water, 500 mL ~ 600 mL each time, to wash the precipitation
with the decantation method. After each washing and before decantation, fully stir the
manganese in the water to make it precipitate. Use a very diluted sulphuric acid
solution [adding dropwise 2 drops of sulphuric acid (ρ 1.84 g/mL) to each 1 000 mL of
solution] to wash twice with the same method.
In the meanwhile, prepare a funnel of caliber 15 cm, take a filter disc of diameter 5 cm
to place on the funnel and cover the filter disc with a thin layer of purified asbestos pulp
(or use a porcelain Buchner funnel to replace the filter disc). After the last washing,
transfer manganese dioxide to the filter, use warm water to wash until there is no
sulfate ion, place it on the porcelain disc, and dry in an oven at 105°C. Grind
manganese dioxide in a mortar to make it pass through a screen of pore diameter 0.8
mm and dry fully at 105°C.
4.6 Soda asbestos, solid, grain size 2.00 mm ~ 0.90 mm or 0.90 mm ~ 0.63 mm.
Avoid exposure to the air.
4.7 Chromic acid saturated sulphuric acid. weigh 30 g of potassium dichromate to
place in a 600-mL beaker, add 30 mL ~ 40 mL of water, heat to dissolve, evaporate at
low temperature to a nearly dry and crystalline state, add 500 mL of sulphuric acid (ρ
1.84 g/mL) and heat slightly to dissolve the crystal.
4.8 Degreasing cotton.
4.9 Glass wool.
5 Apparatus
Except for the following specifications, only common laboratory apparatus is used in
analysis.
Figure of apparatus.
1 - oxygen flask 2 - partial pressure meter 3 - flowmeter 4 - surge flask
5 - gas-washing flask 6 - gas-washing flask 7 - gas-washing flask 8 - drying and oxygen
purification tower
9 - pipe furnace 10 - porcelain boat 11 - porcelain tube 12 - filter tube
13 - sulphur removal flask 14 - quadruple ball 15 - water absorption flask 16 - carbon dioxide
absorption flask
Figure 1 -- Apparatus
5.1 Oxygen flask which is equipped with a pressure regulating value (see Figure 1).
5.2 Gas-washing flask (see Figure 1) which contains chromic acid saturated
sulphuric acid solution (4.7) and whose loading quantity is about one third of the height
of the flask.
5.3 Drying and oxygen purification tower (see Figure 1). containing soda asbestos
(4.6) as the upper layer, anhydrous magnesium perchlorate (4.3) as the lower layer
and glass wool as the partition and containing glass wool (4.9) on the top and at the
bottom.
5.4 Pipe furnace (see Figure 1) which is equipped with thermocouples and automatic
temperature control. High-frequency heating equipment may be used as the high-
temperature heating equipment.
5.5 Porcelain boat (see Figure 1) which is 77 mm, 88 mm or 97 mm long. Before use,
burn in a high-temperature furnace for 1 h ~ 2 h at 1 000°C and place in a desiccator
containing allochroic silicagel as standby after cooling.
5.6 Porcelain tube (see Figure 1) of length 600 mm and inner diameter 23 mm (or
porcelain tubes of simila...
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.