GOST 12345-2001

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  ГОСТ 12345-2001

GOST 12345−2001 (ISO 671−82, ISO 4935−89) Steel alloyed and high alloy. Methods of determining sulphur

GOST 12345−2001
(ISO 671−82, ISO 4935−89)

Group B39

INTERSTATE STANDARD

STEEL ALLOYED AND HIGH-ALLOYED

Methods of determining sulphur

Alloyed and high-alloyed steels. Methods of sulphur determination

ISS 77.080.20
AXTU 0709

Date of introduction 2002−03−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 145 «monitoring Methods of steel products"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (minutes N 19 dated 24 may 2001)

The adoption voted:

3 Annex a of this standard corresponds to international standard ISO 671−82* «Steel and cast iron. Determination of the mass fraction of sulfur titrimetric method after combustion of the sample of the sample» in terms of distribution and sampling.
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link. — Note the manufacturer’s database.

Appendix B of this standard complies with international standard ISO 4935−89 «Steel and cast iron. Determination of the mass fraction of sulphur by infrared absorption spectroscopy after combustion of the sample the sample in the induction furnace» in terms of distribution and sampling

4 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated 28 August 2001 No. 356-St inter-state standard GOST 12345−2001 introduced as the national standard of the Russian Federation from March 1, 2002

5 REPLACE GOST 12345−88

6 REISSUE. November 2006

1 Scope

This standard establishes titrimetric methods for the determination of sulfur: iodide todaty and tetraborates (when the mass fraction of sulfur from 0.002% to 0.50%) methods for the determination of sulfur, based on the use of automatic analysers: coulometric and infrared absorption (at a mass fraction of sulfur from 0.001% to 0.50%) in the alloy and high-alloy steels.

Allowed sulfur determination titrimetric method ISO 671−82, is given in Appendix A, and by infrared spectroscopy according to the international standard ISO 4935−89 given in Appendix B.

2 Normative references

The present standard features references to the following standards:

GOST 177−88 Hydrogen peroxide. Specifications

GOST 546−2001 copper Cathodes. Specifications

GOST 859−2001 Copper. Brand

GOST 2603−79 Acetone. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 4145−74 Potassium sulfate. Specifications

GOST 4199−76 Sodium tetraborate 10-aqueous. Specifications

GOST 4202−75 Potassium ignominously. Specifications

GOST 4232−74 Potassium iodide. Specifications

GOST 4234−77 Potassium chloride. Specifications

GOST 4328−77 Sodium hydroxide. Specifications

GOST 5583−78 (ISO 2046−73) Oxygen gas technical and medical. Specifications

GOST 9147−80 Glassware and equipment lab porcelain. Specifications

GOST 10163−76 Starch soluble. Specifications

GOST 13610−79 carbonyl Iron radio. Specifications

GOST 14261−77 hydrochloric Acid of high purity. Specifications

GOST 16539−79 Copper (II) oxide. Specifications

GOST 20490−75 Potassium permanganate. Specifications

GOST 24363−80 Potassium hydroxide. Specifications

GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST 28473−90 Iron, steel, ferroalloys, chromium and manganese metal. General requirements for methods of analysis

3 General requirements

General requirements for methods of analysis GOST 28473.

4 Titrimetric iodide todaty method for the determination of sulfur

4.1 the essence of the method

The method is based on the combustion of a sample of steel in a current of oxygen at a temperature of 1300−1400 °C in the presence of the beach, followed by absorption of sulphur dioxide with water and titration of the resulting sulphurous acid titrated with a solution of a mixture of odnomodovogo of potassium and iodide of potassium in presence of starch indicator.

4.2 Instrument

Setting for titration of iodide udatnogo method for the determination of sulfur (figure 1) consists of an oxygen tank or coloradobased 1, equipped with a pressure reducing valve and pressure gauge for starting and regulating the current of oxygen; Tishchenko flask 2containing a solution of potassium permanganate 40 g/lsolution of potassium hydroxide or sodium 400 g/DM; a drying column 3 isfilled in the lower part of soda lime or soda asbestos (oscarito), and the top — rate of magnesium to clean up the oxygen in the dry way; the rotameter or gas meter 4; double tap 5; mullite refractory tube 6 an inner diameter of 18−22 mm and a length of 650−800 mm, the ends of which must project from the furnace is not less than 200 mm on each side. The tube is closed by a metal gate or a well-fitting rubber stoppers with holes, into which is inserted a glass tube for connecting tubes. To prevent burning the rubber tubes their inner surfaces close the asbestos pads placed on ends of glass tubes. Removing the impurity of sulfur from the refractory tube, its work is calcined at operating temperature over the entire length in a tubular furnace 7, providing thermal heat to 1400 °C; thermocouple with a regulator 8 for regulating the furnace temperature; unglazed porcelain boat 9 according to GOST 9147 intended for burning the sample and can withstand temperatures up to 1400 °C. Before the boat is calcined at operating temperature in flowing oxygen and then stored in a desiccator according to GOST 25336. Socket cover of the dryer must not be covered by lubricating substance; the transformer 10 for regulating the operating voltage of the furnace; a glass tube 11 with an extension or gorkaltseva tube filled with glass or plain wool for cleaning gas mixture leaving the kiln, the solids produced by combustion of the sample and entrained from the furnace by a current of oxygen; the crane 12; microburette 13 or burette with a capacity of 25 cm, containing a titrated solution of iodide of potassium Iodate; absorption vessel 14; reference vessel comparison 15.

Figure 1 — Installation for determination of mass fraction of sulphur iodide Iodate method

Figure 1 — Installation for determination of mass fraction of sulphur iodide Iodate method

The absorption vessel consists of two glass vessels (figure 2), connected by two glass rods. In the vessel 1 is in the process of absorption and titration of the sulfur dioxide in the vessel 2 is a solution of the comparison to control the color of the solution during titration. The vessel 1 is soldered l-shaped glass tube with a diameter of 7 mm, terminating in a bubbler with a float, through which the absorption vessel receives the gaseous products of combustion resulting from the burning sample. At the bottom of the vessel has a tap to drain the solution.

Figure 2 — Device absorption vessel

Figure 2 — Device absorption vessel

Allowed to use absorption cells of another shape of the vessel without comparison.

The hook with which the boat is introduced into the tube for flaring and extracted from it, are made of heat-resistant low-carbon wire of square or circular cross-section with side of square or diameter 3 to 5 mm and a length of from 500 to 600 mm.

4.3 Reagents and solutions

The oxygen purity not less than 99,0% according to GOST 5583.

Hydrochloric acid according to GOST 3118 or GOST 14261.

Potassium hydroxide according to GOST 24363 or sodium hydroxide according to GOST 4328.

Potassium permanganate according to GOST 20490, solution 40 g/lsolution of potassium hydroxide 400 g/DM: 40 g of potassium permanganate dissolved by heating at 700−800 cmof water. After cooling, the solution was added 400 g of potassium hydroxide and dilute with water to 1000 cm. The solution should be freshly prepared.

The rate of anhydrous magnesium (angeren).

Potassium ignominously according to GOST 4202.

Potassium iodide according to GOST 4232.

Potassium iodide-Iodate, titrated a solution of 0,111 g odnomodovogo potassium, 15 g of potassium iodide and 0.4 g of potassium hydroxide were placed in a glass with a capacity of 250 cm, and dissolved in 100 cmof water. The solution is transferred into a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. The solution was stored in a flask made of dark glass.

1 cmcorresponds to a solution of 0.00005 g of sulfur. For the determination of sulfur in materials containing less than 0,020% of the sulphur titrated solution was diluted in the ratio of 1:1, 1:4, 1:6.

The soluble starch according to GOST 10163.

The solution of the mass concentration of 0.5 g/l: 0.5 g soluble starch, triturated in a porcelain mortar with 50 cmof water and the suspension is poured a thin stream of 950 cm. of boiling water. To the obtained solution poured 15 cmof hydrochloric acid, cooled and poured in small portions with stirring a solution of the iodide-Iodate to obtain a pale-blue color of the solution.

Marshes: copper metal according to GOST 546 or GOST 859; copper oxide according to GOST 16539, OS. h; carbonyl iron radio GOST 13610.

Allowed the use as flux of vanadium pentoxide.

4.4 Preparation for assay

To bring the installation (figure 1) in working condition, the ends of the mullite refractory tube is closed by a metal stopper or a rubber cap embedded with glass or non-corrosive metal tubes. Then one end of the tube connected by a rubber hose with a balloon containing oxygen, or coloradoboulder through absorption flasks for the purification of oxygen, and the second absorption vessel. Connections should be as short as possible. After that, both vessels poured at 50−80 cmstarch solution a pale blue color. Pass a current of oxygen at a rate of 2 DM/min If the starch solution in the absorption vessel 3−4 min colorless (indicating the selection of the porcelain tube gas oral rehydration solution jednoucelove potassium), then, without stopping the current of oxygen, the absorption solution flow from burette a solution of potassium odnomodovogo as long as the color intensity of the solution into the absorption and control the blood vessels will not be the same.

The portion of the system between the combustion tube and the absorption vessel should be dry.

To check the installation for leaks close the valve 12 and is fed into the oxygen system. The installation is sealed, if the flask 2 after some time will stop the appearance of gas bubbles. Otherwise, the installation should be disassembled, the glass parts and the connecting pipe check valves wipe clean, coat with vaseline and re-check the installation for leaks.

Before starting work, after changing the tubes burn two or three arbitrary hinge steel.

4.5 analysis

4.5.1 depending on the mass fraction of sulfur in the sample take a sample in the amount shown in table 1.


Table 1

4.5.2 the sample calcined steel is placed in a porcelain boat and add an even layer of 1 g of copper or copper oxide in the analysis of alloy steels. In the analysis of high-alloyed steels was added 1.5 g of a mixture of marshes, consisting of iron and copper or iron and copper oxide, in both cases in a ratio of 1:2.

Close valves 5 and 12. A boat with suspension of sample and flux was placed in the most heated part of the tube which is quickly closed by a metal stopper or a rubber stopper, then gently open the valve 5 and oxygen into the furnace at a rate of 2 DM/min of the Analyzed sample is held under pressure for 20 s, gently open the faucet 12 and serves the gas in the absorption vessel.

In the combustion process of the sample is necessary to monitor the change in color of the solution in the absorption vessel in which the absorption of sulfur oxides. During combustion of the sample the coating solution in the absorption vessel should be close to the color of the solution in the test vessel. For this to the solution in the absorption vessel (decreasing color intensity) is added from burette dropwise a solution of potassium odnomodovogo.

The titration is complete when the color intensity of the solutions in both vessels is the same. The duration of the measurement (combustion of sample metal) — 3 min.

4.5.3 To verify the completeness of combustion of sample oxygen to continue feeding for 30 s. If the intensity of color of the solution does not decrease, the definition is complete. After burning a test portion of the boat removed from the furnace hook, the absorption solution is decanted from the vessel and wash vessel with water.

4.5.4 For the relevant amendment to the result of the analysis carried out control experience.

4.6 processing of the results

4.6.1 Mass fraction of sulfur , %, is calculated by the formula

, (1)

where  — volume of the solution odnomodovogo potassium consumed in the titration of a solution of test sample, cm;

the volume of the solution odnomodovogo potassium consumed in the titration of a solution in a control experiment, cm;

 — mass concentration of the solution odnomodovogo potassium, g/cmsulphur;

the weight of analyzed sample, g.

4.6.2 Mass concentration of a solution of potassium odnomodovogo set according to the standard model steel, similar in chemical composition and mass concentration of sulphur analysed steel in accordance with 4.5.

4.6.3 Mass concentration of the solution odnomodovogo potassium , g/cmsulphur, calculated by the formula

, (2)

where  — mass fraction of sulfur in the standard sample, %;

 — weight of standard sample, g;

the volume of the solution odnomodovogo potassium consumed in the titration of a standard solution of the sample, cm;

the volume of the solution odnomodovogo potassium consumed in the titration of a solution in a control experiment, cm.

4.6.4 Norms of accuracy and norms of accuracy control of determination of sulphur mass fraction are shown in table 2.


Table 2

5 Tetraborate method for the determination of sulfur

5.1 the essence of the method

The method is based on the combustion of the sample steel in flowing oxygen at 1300−1400 °C in the presence of flux, with subsequent absorption of the sulfur dioxide oxidizing solution consisting of potassium sulfate and hydrogen peroxide. The resulting sulfuric acid octarepeat solution of sodium tetraborate in the presence of a mixture of indicators methyl red and methylene blue.

5.2 Instrument

Setup for the determination of sulfur tetraborate method (figure 3) consists of an oxygen tank or coloradobased 1, equipped with a pressure reducing valve and pressure gauge for starting and regulating the current of oxygen; Tishchenko flask 2containing a solution of potassium permanganate 40 g/lsolution of sodium hydroxide 400 g/DM; a drying column 3 isfilled in the lower part of soda lime or soda asbestos (oscarito), and the top — rate of magnesium to clean up the oxygen in the dry way; flowmeter 4for measuring the flow of oxygen; the three-way tap 5 to start the oxygen in the absorption vessel through the heater or bypassing the furnace; refractory mullite tube 6 an inner diameter of 18−20 mm and a length of 650−800 mm, designated for combustion of the sample. The ends of the tube should protrude out of the oven at least 200 mm on each side. The tube is closed by a metal gate or a well-fitting rubber stoppers with holes, into which is inserted a glass tube for connecting tubes. To prevent burning the rubber tubes their inner surfaces close the asbestos pads placed on ends of glass tubes. Removing the impurity of sulfur from the refractory tube, its work is calcined at operating temperature over the entire length in a tubular furnace 7, providing thermal heat to 1400 °C; thermocouple with a regulator 8 for regulating the furnace temperature porcelain boat 9 according to GOST 9147 intended for burning the sample and can withstand temperatures up to 1400 °C. Before the work boat was calcined in flowing oxygen at operating temperature. Storage of calcined boats use desiccator with GOST 25336, socket cap which should not be covered by lubricating substance; a transformer 10 for voltage regulation of the furnace; the glass tube 11 isfilled with glass wool for cleaning gas mixtures of oxides produced during combustion; crane 12 to isolate the furnace from the absorption vessel; microburette 13; absorption vessel 14; vessel comparison 15; bubbler tube 16; a rubber tube 17 to supply oxygen through the bubbler tube into the absorption vessel, bypassing the oven.

Figure 3 — Installation for determining the mass fraction of sulfur tetraborate method

Figure 3 — Installation for determining the mass fraction of sulfur tetraborate method

The connection between the individual parts of the installation should be short.

The hook with which the boat is introduced into the tube for flaring and extracted from it, are made of heat-resistant low-carbon wire of square or circular cross-section with side of square or diameter of 3 to 5 mm, length from 500 mm to 600 mm.

5.3 Reagents and solutions

The oxygen purity not less than 99,0% according to GOST 5583.

The rate of anhydrous magnesium (angeren).

Potassium permanganate according to GOST 20490, a solution of 40 g/DMsolution of sodium hydroxide 400 g/DM: 40 g of potassium permanganate dissolved by heating at 700−800 cmof water. After cooling, the solution was added 400 g of sodium hydroxide and dilute with water to 1000 cm. The solution should be freshly prepared.

Calcium chloride anhydrous according to GOST 4234.

Potassium sulfate according to GOST 4145.

Hydrogen peroxide according to GOST 177, a solution of 300 g/DM.

The absorption solution: 5 g of potassium sulfate dissolved in 300 cmpre-boiled and cooled water, add 100 cmof hydrogen peroxide solution and adjusted to 2500 cmof water, previously boiled and cooled.

Methyl red (CHONNa).

Methylene blue (CHNSCl·3HO), a solution of 1 g/DM.

A mixture of indicators: 0.1 g methyl red dissolved with stirring and heated to 300 cmof ethyl alcohol and mixed with 50 cmof a solution of methylene blue.

Sodium 10-water tetraborate (NaBO·10HO) according to GOST 4199, titrated solution: 1,1894 g of sodium tetraborate dissolved in pre-boiled water in a volumetric flask with a capacity of 2000 cm. The same water to refill the flask to the mark and the solution was stirred.

1 cmcorresponds to a solution of 0.00005 g of sulfur.

For the determination of sulfur in materials containing less than 0,020% of the sulphur titrated solution was diluted in a 1:1 ratio.

Marshes carbonyl iron radio GOST 13610, copper metal according to GOST 546 or GOST 859, the copper oxide according to GOST 16539.

5.4 Preparation for assay

To bring the installation (figure 3) in working condition, the ends of the mullite refractory tube is closed by a metal stopper or a rubber cap embedded with glass or non-corrosive metal tubes. One end of the tube connected by a rubber hose with a balloon containing oxygen, through absorption flasks for the purification of oxygen, and the second absorption vessel.

Oven heated to 1300−1400 °C. Open oxygen tank and passed it through the furnace of the absorption vessel at a rate of 1.2 DM/min on the rotameter.

Then, in the absorption vessel 14 pour 50 cmof absorption solution and 5−6 drops of mixture indicators. The solution is neutralized with a few drops of the titrated solution of sodium tetraborate to obtain a stable light-green color of the solution.

During the neutralization absorptive solution, oxygen was passed through the furnace of the absorption vessel.

To check the installation for leaks prior to analyzing the burn two or three sample standard sample of steel in the presence of flux at 5.5.

For the relevant amendment to the result of the analysis of the sample necessary to conduct a blank experiment by burning two batches of flux.

5.5 analysis

Depending on the mass fraction of sulfur take a charge in the amount shown in table 1.

The sample calcined steel is placed in a porcelain boat and covered with a uniform layer of 1 g of copper or copper oxide in the analysis of alloy steels. In the analysis of high-alloyed steels used 1.5 g of a mixture of marshes, consisting of iron and copper or iron and copper oxide, in both cases in a ratio of 1:2.

Close the valve 12 (figure 3), connecting the furnace to the absorption vessel 14. The tap 5is turned in the position at which oxygen enters the absorption vessel through the tube 17, bypassing the oven.

Open porcelain tube and put a boat with a charge of metal and flux in the most heated portion of the porcelain tube, which is closed by a metal stopper or a rubber stopper and heat the charge of metal at 1300−1400 °C for 1 min without oxygen. During heating of the sample gas should barbotirovat of the absorption vessel, to prevent the suction of solution into the bubble tube. Turn the tap 5 to the position at which oxygen enters the furnace, then quickly open the valve 12 and burn a portion of the metal in a current of oxygen for 3 min.

The formed sulfur dioxide is absorbed by the absorption solution to form sulfuric acid, resulting in a change in solution colour from light green to crimson. From the burette is poured dropwise a solution of sodium tetraborate to obtain a stable light green in color. Titration is considered complete when the intensity of the color of the solution will not change within 1 min.

Stop the flow of oxygen into the furnace. To do this, block the crane 12 and quickly turn the tap 5 to the position at which oxygen enters the absorption vessel, bypassing the furnace and remove the boat from the tube.

The portion of the system between the combustion tube and the absorption vessel should be dry; for reliability before you start it is washed with ethanol and ether.

It is unacceptable entrainment of the absorption solution in the bubbler tube 16.

If the combustion process of mounting the metal or at the time of switching of the cranes still there is entrainment of the absorption solution in the bubbler tube, then drain the solution from the absorption vessel and dry it by a long transmission hot stream of oxygen passing through the furnace or to replace the absorption vessel by another vessel with a dry bubbler tube.

To prevent the suction of the absorption solution in the bubbler tube is in the oxygen supply to the absorption vessel through the three-way valve 5 and the rubber tube 17is allowed three-way valve to remove the supply of oxygen to carry out different speeds with two independent sources. Through the top outlet of the bubbler tube continuously to provide oxygen at a speed of 0.3 DM/min, the tap 12 should be closed, and during burning of the sample metal faucet 12 to open and oxygen to flow through the furnace and the lower outlet of the bubbling tube at a rate of 1.2 DM/min, it is necessary to exclude a one-minute delay in the combustion process of the sample metal. After combustion of the sample metal for 3 min and titrovaniya absorption solution faucet 12 to block, open the tube and unload the boat from the tube; the oxygen in the absorption cell to continue to serve through the top outlet of the bubbler tube at a speed of 0.3 DM/min.

5.6 processing of the results

5.6.1 Mass fraction of sulfur , %, is calculated by the formula

, (3)

where mass concentration of a solution of borax, g/cmsulphur;

 — the volume of solution of borax, used for titration of sample, cm;

 — the volume of solution of borax, used for titration in a control experiment, cm;

 — the weight of the portion,

The mass concentration of the solution of sodium tetraborate set according to the standard model steel, similar in chemical composition and mass concentration of sulphur analysed steel in accordance with 5.5.

5.6.2 Mass concentration of a solution of borax , g/cmsulphur, calculated by the formula

, (4)

where  — mass fraction of sulfur in the standard sample, %;

 — weight of standard sample, g;

 — the volume of solution of borax, used for titration of standard solution of the sample, cm;

 — the volume of solution of borax, used for titration in a control experiment, cm.

5.7 Norms of accuracy and norms of accuracy control of determination of sulphur mass fraction are shown in table 2.

6 Coulometric method for the determination of sulfur

6.1 the essence of the method

The method is based on the combustion of a sample of steel in a current of oxygen in presence of flux at a temperature of 1300−1400 °C, absorbing the resulting sulfur dioxide absorption solution with a particular initial pH~3.3 and subsequent measurement in the apparatus for coulometric titration the amount of electricity necessary to restore the original pH value, which is proportional to the mass fraction of sulfur in the sample analyzed sample.

6.2 Instrument

Coulometric installation of any type including in the set of corrector weight for the precision of the analysis results required by this standard.

Boat porcelain with GOST 9147, pre-calcined in flowing oxygen at operating temperature. When determining the mass fraction of sulfur less than 0.005% pumps calcined directly before analysis.

Tubular resistance furnace providing heating temperature up to 1400 °C allows the use of induction furnaces.

Laboratory scales or auto (corrector mass). When you use automatic weights the measurement error of the mass of sample should not exceed ±0.001 g.

6.3 Reagents and solutions

The oxygen purity not less than 99,0% according to GOST 5583.

Absorption and support solutions in accordance with the instruction attached to the device, and the type of the used coulometric setup.

The beach: vanadium pentoxide. Use as a beach radio carbonyl iron according to GOST 13610, and tungsten when using induction furnaces.

Ether sulfate (medical).

Allowed to use other volatile organic solvents: acetone according to GOST 2603, chloroform.

6.4 Preparation for assay

Before analysis the installation of a drive according to the instructions supplied with the device.

Before starting work, after changing the tubes to saturate the system to burn two or three arbitrary linkage of steel with a mass fraction of sulphur 0,10% — 0,20%.

The calibration of an instrument performed on standard specimens of carbon steel.

6.5 analysis

In the boat put the weight of steel weight of 0.25−0.50 g depending on the mass fraction of sulfur in the sample. Cover the suspension became a uniform layer of flux.

If necessary, the sample must be washed with ether or other volatile organic solvent and air dry.

The boat with the charge of metal and flux is placed in the most heated portion of the porcelain tube, which quickly closed the metal gate, press the button «reset» and burn a portion of the metal at a temperature of 1300−1400 °C.

In the burning process of mounting the metal on the digital display by a continuous readout. The analysis is complete, if the figures on the scoreboard don’t change within one minute, or change the amount of idle accounts, but the arrow indicator pH will be set to its original position.

In parallel through all stages of the analysis carried out the analysis of control experience. For this purpose calcined in a porcelain boat is placed a flux — vanadium pentoxide is a mass of 0.2 or 0.4 g (depending on the chemical composition of the analyzed steel) and burn it at operating temperature during time spent on the burning of the sample analyzed material is steel.

6.6 processing of the results

6.6.1 Mass fraction of sulfur , %, is calculated by the formula

, (5)

where  — the weight of the portion at which the calibrated device, g;

 — the readings obtained from the combustion of a sample of analyte material, %;

 — the arithmetic mean of the readings obtained from the combustion of the flux, during the reference experiment, %;

 — the mass of the analyzed sample metal,

When you use corrector mass formula takes the form

. (6)

6.6.2 Standards of accuracy and standards of accuracy control of determination of sulphur mass fraction are shown in table 2.

7 Infrared absorption method for the determination of sulfur

7.1 the essence of the method

The method is based on the combustion of a sample of steel in a current of oxygen at a temperature of 1700 °C and determining the quantity of formed sulfur dioxide by measuring its absorption of infrared radiation.

7.2 Instrument

Any type of automatic analyzer, based on the principle of absorption of infrared radiation, ensuring the accuracy of the analysis required by this standard.

7.3 Reagents

The oxygen purity not less than 99,0% according to GOST 5583.

Ether sulfate (medical).

Allowed to use other volatile organic solvents: acetone according to GOST 2603, chloroform.

The smoother used depending on the type of analyser used for analysis.

7.4 test Preparations

Before analysis the installation of a drive in accordance with the instructions supplied with the device.

The calibration of an instrument carried out on standard samples of steels of the carbon.

7.5 analysis of

The analysis is carried out in accordance with the instructions supplied with the device.

If necessary, the sample must be washed with ether or other volatile organic solvent and air dry.

For making the appropriate corrections in the result of sample analysis spend control experience.

7.6 processing of the results

7.6.1 Mass fraction of sulfur , %, is calculated by the formula

, (7)

where  — the readings obtained by burning the sample of the analyzed material, %;

 — the readings obtained from the combustion of smoother, % (reference experiment).

Norms of accuracy and norms of accuracy control of determination of sulphur mass fraction are shown in table 2.

Annex a (mandatory). Steel and cast iron. Determination of the mass fraction of sulfur titrimetric method after combustion of the sample sample (ISO 671−82)

APPENDIX A
(required)

A. 1 Scope

This standard specifies the titrimetric method of determination of mass fraction of sulfur in the steel and iron after burning the test sample in flowing oxygen.

A. 2 Normative references

The present standard features references to the following standards:

GOST 5583−78 (ISO 2046−73) Oxygen gas technical and medical. Specifications

GOST 7565−81 (ISO 377−2-89) Iron, steel and alloys. Methods of sampling for chemical composition

A. 3 the essence of the method

The method is based on the combustion of the sample the sample in flowing oxygen at a temperature of 1450 °C in the presence of, if necessary, a metal flux, absorbing the resulting sulfur dioxide oxidizing solution consisting of potassium sulfate and hydrogen peroxide, and ottitrovannom formed sulfuric acid standard solution tetraborate sodium.

A. 4 Reagents

In the analysis, unless otherwise specified, use reagents of known analytical purity, distilled water or water of equivalent purity.

Note — to verify the sulphur content in the reagents is carried out, the control experience and, if necessary, make the appropriate amendments to the analysis results.

A. 4.1, the Oxygen purity not less than 99,0% according to GOST 5583 free of impurities of sulfur.

A. 4.2 Asbestos soda (ascarid), particle size of about 2 mm.

A. 4. The rate of Magnesium 3 Mg (ClO), a particle size of about 2 mm.

A. 4.4 Pure iron of known sulphur content.

A. 4.5 Marshes: iron, copper, tin with a known sulphur content.

A. 4.6, the Absorption solution: 5 g of potassium sulfate dissolved in 200 cmof boiled and cooled water, add 100 cmof hydrogen peroxide and adjusted to 2500 cmof boiled and cooled water.

A. 4.7 Sodium tetraborate, standard solution corresponding to 0,010% sulfur to 1 g/cmsample: 2,3839 g of sodium tetraborate (NaBO10HO) is weighed with an accuracy to the fourth decimal place and dissolved in 2000 cmof boiled and cooled water.

A. 4.8 Solution mixture of indicator: 0.1 g of methylene blue and 0.3 g methyl red dissolved in distilled water and diluted with distilled water to 500 cm.

Note — the Ratio between the value of the batches of the indicators may be installed depending on the sensitivity of the eye of the analyst. The color intensity of the indicator can be estimated using the optical device.

A. 5 Instrument

Setup for analysis is shown in figure A. 1. Individual components of the installation are connected airtight connection tubes.

Figure A. 1 — Installation for determination of sulphur mass fraction tetraborate method

Figure A. 1 — Installation for determination of sulphur mass fraction tetraborate method

A. 5.1, the oxygen Source 1 (oxygen tank or coloradobased) fitted with a pressure reducing valve and pressure gauge start and regulate the flow of oxygen.

A. 5.2 a Cleaning and drying column 2filled with soda asbestos and magnesium rate of (A. 4.3).

A. 5.3 flow meter 3 for measuring the flow of oxygen from 0.2 to 3 DM/min.

A. 5.4 the tubular furnace 9, providing inside the tube a constant temperature of 1420 °C.

A. 5.5 Refractory tube 6, intended for the combustion of samples at 1450 °C, consisting of the widest portion of an inner diameter of 27 mm and a length of 450 mm and a narrow part inner diameter of 3 mm and a length of 250 mm.

Notes

1 where the constriction of the tube should have the Central the hot zone.

2 Connection tube 6 from the gas outlet tap 10 is exposed to a hot gaseous mixture leaving the furnace, and therefore cool, especially if it made of natural or synthetic rubber. Cooling should be such that the temperature at the inner surface of the joint, are in contact with the gaseous mixture does not exceed 40 °C.

A. 5.6 Tap to start the oxygen 4.

A. 5.7 Device 5 to start the oxygen window that allows you to visually observe the combustion process (figure A. 2).

Figure A. 2 — apparatus for combustion tube with water cooling

1 — stained glass set in epoxy resin; 2 — a sealing rubber pad; 3 — water chamber; 4 — removal of water; 5 — tube combustion; 6 — rubber sealing strip; 7 — water flow; 8 — oxygen supply; 9 — corsicanna* strip; 10 — bushing with the notch

Figure A. 2 — apparatus for combustion tube with water cooling

_______________
* The text of the document matches the original. — Note the manufacturer’s database.

A. 5.8 Platinum — rhodium thermocouple 7high-temperature end of which is located at the outer surface of the tubing near the pumps and refractory capsules. You must install and periodically check the correlation between the temperature inside the tube 6 and the meter.

A. 5.9 Boat 8made of refractory material, with a wide, flat bottom length 80 to 100 mm, a height of 8−9 mm, 15−16 mm wide, designed to burn a sample and can withstand twice the heat to 1420 °C (figure A. 3).

Figure A. 3. Boat for burning sample

1 crew; 2 — capsule

Figure A. 3

A. 5.10 Refractory capsule 15 (figure A. 1), made of a material consisting of aluminum dioxide and 12.0%-15,0% of silicon oxide, an inner diameter of 14 mm, outer diameter 16 mm, length 50 mm. the porosity of the capsule ensures a constant uniform flow of gas across the surface of the sample for a given gas flow between 4 and 5 DM/min and a pressure of 250 mm water column (figure A. 3). Before application the capsule boat and calcined in a stream of pure oxygen at 1420 °C for 10 min and stored in a desiccator.

A. 5. The Gas inlet 11 of the crane 10 with the internal diameter of 2.5 mm, designed to prevent lifting of the absorbent solution in the bubbler tube when the oven was opened in order to insert in it a boat of a refractory capsule, and during preheating, when the result of oxidation of metal in the furnace creates a vacuum.

A. 5.12 Bubbler tube 13 (figure A. 1) with holes is shown in figure A. 4.

Figure A. 4 — Bubbling tube with holes

Figure A. 4 — Bubbling tube with holes

A. 5.13 the Absorption vessel 14 with a diameter of not less than 35 mm, height 140 mm.

A. 5.14 Burette 12 with a capacity of 10 cm, filled with a standard solution of sodium (A. 4.7).

A. 5.15 Gas tube 11 must be as short as possible.

A. 6 Sampling and sample preparation

The selection and preparation of samples for analysis is carried out in accordance with the requirements of GOST 7565.

A. 7 Methods of analysis

In connection with the danger of explosion when carrying out analysis it is necessary to exclude all possible contact rate of magnesium with organic compounds.

A. 7.1 Preparing for analysis

In order to ensure tightness of installation, the completeness of burnout of the sample and the absence of sulfur in the refractory materials, it is necessary prior to analysis to make a preliminary determination of sulphur in several batches of steel or cast iron with a known mass fraction of sulfur. The leak test apparatus can be conducted without entering the boat with the capsule in the tube for ignition.

Note — the Results obtained in these definitions, as well as the difference between the average value and known mass fraction of sulfur in the analyzed sample should not differ from the corresponding values inherent in all methods of determination of sulphur.

A. 7.2 Linkage

The weight of the portion of the sample in the form of a small chip the size of a few tenths of a millimeter should be:

1,0±0.001 g — with mass fraction of sulfur in the sample is less than 0.10%;

0,5±0,001 g — when the mass fraction of sulfur in the sample 0,10%-0,20%;

when the mass fraction of sulfur, more than 0.20% of the value of the sample test portion must be calculated so that the mass fraction of sulfur in it was not more than 1000 micrograms. To maintain consistent combustion conditions a portion of the sample should be Supplement up to 1 g pure iron (A. 4.4).

A. 7.3 analysis

A. 7.3.1 Burning megaromania steels and cast irons

Electric furnace 9 is heated so that inside tube temperature is at least 1420 °C. Open valves 4 and 10, transmit oxygen at a rate of 1.2 DM/min through a furnace in a vessel with absorption solution of (A. 4.6), and the solution level must rise by 80 mm above the holes of the bubbler tube 13.

Added to the absorption solution of 4−5 drops of mixture indicators (A. 4.8) and neutralize with the standard sodium tetraborate solution (A. 4.7) to obtain a stable light-green color of the solution. Note the level of standard solution in a burette in cubic centimeters.

Close valves 4 and 10, stopping the supply of oxygen. Open the damper input device 5 and placed the boat with the capsule and sample in a wide, the most heated part of the combustion tube 6. Close the choke input device 5, opens the input tap 4 for a flow of oxygen at a rate of 1.2 DM/min, and then quickly open the valve for the gas outlet 10.

Weighed sample is burned for 3 min in an oxygen flow. The resulting sulfur dioxide is completely transferred from the tube combustion in an absorption vessel where it is absorbed by absorption solution which is titrated over a 4 min standard solution of sodium tetraborate (A. 4.7) to obtain a stable light green in color. Note the level of standard solution in a burette in cubic centimeters.

The end of the titration can also be set by the potentiometric method.

A. 7.3.2 Burning heat-resistant steels and cast irons

Due to the fact that the initial stage of burning steel and cast iron is difficult to mount a sample, you must add a certain amount of flux (A. 4.5), but it should be borne in mind that the size of the pumps and capsules designed to burn hitch weight no more than 1.2 g.

A. 8 Handling of results

A. 8.1 Mass fraction of sulfur , %, is calculated by the formula

, (A. 1)

where 0,00010 — mass concentration of a solution of sodium tetraborate, g/cmsulphur;

 — the amount of sodium tetraborate solution, consumed for titration, cm;

 — the weight of the portion of the sample,

APPENDIX B (mandatory). Steel and cast iron. Determination of the mass fraction of sulphur by infrared absorption spectroscopy after combustion of the sample the sample in an induction furnace (ISO 4935−89)

APPENDIX B
(required)

B. 1 Scope

This standard specifies an infrared absorption method for the determination of the mass fraction of sulfur in steel and cast iron, after combustion of the sample in an induction furnace.

The method used in the determination of the mass fraction of sulfur in the range of 0.002% to 0.10%.

B. 2 Normative references

The present standard features references to the following standards:

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 5583−78 (ISO 2046−73) Oxygen gas technical and medical. Specifications

GOST 7565−81 (ISO 377−2-89) Iron, steel and alloys. Method of sampling for chemical composition

GOST 29169−91 (ISO 648−77) oils. Pipette with one mark

GOST 29251−91 (ISO 385−1-84) oils. Burette. Part 1. General requirements

B. 3 the essence of the method

The method is based on the combustion of the sample the sample in a high frequency induction furnace in a stream of oxygen in the presence of flux and determining the quantity of the formed sulfur dioxide absorption in the infrared region.

B. 4 Reagents and materials

In the analysis, unless otherwise specified, use reagents of known analytical purity, distilled water or water of equivalent purity.

B. 4.1, the Oxygen purity not less than 99.5% according to GOST 5583.

For removing organic impurities contained in the oxygen before the filter set up with catalyst (powder of copper or platinum), heated to a temperature above 450 °C.

B. 4.2 Iron metal with a mass fraction of sulfur is less than 0.0005%.

B. 4.3 Solvent suitable for washing oily or dirty chips, for example acetone.

B. 4.4 the rate of Magnesium Mg (ClO)particle size 0,7−1,2 mm.

B. 4.5 the Flux — tungsten with a mass fraction of sulfur is not more than 0.0005%. The particle size of the beach depends on the type of the device.

B. 4.6 Standard solutions of sulfur.

Weigh to the nearest 0.1 mg listed in table B. 1 amounts of potassium sulfate, previously dried at 105−110 °C for 1 h to constant weight and cooled in a desiccator. Transfer the sample into seven measuring flasks with a capacity of 100 cm, dissolved in distilled water; bring to mark (with distilled water) and stirred.


Table B. 1

B. 4.7 Askari (asbestos impregnated with sodium hydroxide) a particle size of from 0.7 to 1.2 mm.

B. 5 Equipment

In the analysis, unless otherwise indicated, using only conventional laboratory device.

All laboratory glassware must comply with GOST 29251, 29169 GOST and GOST 1770.

The characteristics of manufactured industrial instrumentation are given in Appendix B.

B. 5.1 Pipette for 50 and 100 cmwith measurement error not more than 1 cm.

B. 5.2 Capsule tin with a diameter of about 6 mm, height 18 mm, volume 0.4 cm, weight 0.3 g

B. 5.3 ceramic Crucibles that can withstand heat in an induction furnace. Before use, the crucible is calcined in an electric furnace in air or a stream of oxygen for two hours at a temperature of 1100 °C and stored in a desiccator.

Note — When determining low sulfur content is recommended to be heated crucibles at a temperature of 1350 °C in a stream of oxygen.

B. 6 Sampling and sample preparation

The selection and preparation of samples for analysis is carried out in accordance with the requirements of GOST 7565.

B. 7 Method of analysis

Safety

The main danger stems from the possibility of burns when the preliminary calcination of the ceramic crucibles and working with the melt. You should use special tongs for crucibles and containers for used cups. When using oxygen cylinders should comply with the usual for this case precautions. After burning the samples must immediately remove the oxygen from the oven as the increased oxygen content in a confined space may cause fire and explosion.

B. 7.1 Preparing for analysis

For pre-cleaning of oxygen passed through a tube filled with Astarita (asbestos impregnated with sodium hydroxide), and the tube with the rate of magnesium. To clean oxygen from dust use a filter of glass wool or a metal grid of stainless steel, which should be cleaned or replaced as necessary. The combustion chamber of the furnace, stand for crucibles and filters must be cleaned periodically to remove deposited oxides.

Each piece of equipment after its inclusion must be warmed within the time specified in the instructions to the device.

After cleaning the combustion chamber of the furnace, replacing or cleaning filters, as well as after an interruption in operation of the device to stabilize its operation it is necessary to conduct the burning of several samples, whose composition similar to the analyzed one.

Through the installation allow oxygen and set the instrumentation to zero. If the scale of the measuring device registers the mass fraction of sulfur from the percentage, you must configure the device for each area of the calibration. To do this, choose a standard sample with a mass fraction of sulfur, close to the maximum calibration interval. Sample analysis is carried out as specified in B. 7.4, and establish the certified value of the mass fraction of sulfur on the measuring scale of the instrument.

Note — the Setting of the scale is carried out before the calibration according to B. 7.4, it does not replace or adjusts itself in calibration.

B. 7.2 the Sample for analysis

The analyzed sample is degreased by rinsing in an appropriate solvent, dried to remove traces of solvent and weighed with an accuracy of 1 mg:

1 g — for the mass concentration of sulfur less than 0.04%;

0.5 g — at a mass fraction of sulfur, more than 0.04 percent.

Note — the weight of the portion may depend on the type of analyser used for analysis.

B. 7.3 Control experience

Before analysis you need to double-spend control experience.

Tin capsule (B. 5.2) is placed in a ceramic crucible (B. 5.3) and slightly press it to the bottom of the crucible. Add pure iron (B. 4.2) in the amount corresponding to the sample of the sample, and (1,5±0,1) g of flux (B. 4.5). Place ceramic crucible with its contents on the stand under the crucible, and raise it to the position of the burning and close the combustion chamber of the furnace. At the end of the cycle, the burning and dimensions and remove the crucible from the combustion chamber and record the readings.

The obtained results are in milligrams of sulphur is transferred by means of a calibration graph and calculate the value of the reference experiment by subtracting the mass of sulphur in iron from the found value (note 1).

The average value of the reference experiment is determined by two parallel results (note 2).

Notes

1 For determining sulfur content in iron is prepared by two ceramic crucible, each of which is placed the tin capsule, lightly pressing it to the bottom of the crucible, add 0,500 g of pure iron (B. 4.2) one ceramic crucible and 1,000 g in a crucible, covering every linkage with a flux (B. 4.5) in the amount of (1,5±0,1) g;

perform with the crucibles of the operations specified in B. 7.4;

the obtained results are in milligrams of sulphur transferred using the calibration curve (B. 7.5).

The mass of sulphur () to 0,500 g of pure iron (B. 4.2) calculate the subtraction corresponding to 0,500 g of pure iron, corresponding to 1,000 g of pure iron. Weight () of sulphur, 1 g of pure iron has twice the mass () of sulfur in 0,500 g of pure iron

. (B. 1)

2 the Average value of the reference experiment should not exceed 0.005 mg of sulfur, and the difference between the values of two parallel measurements in the reference experiment shall not exceed 0,003 mg of sulfur. If these values exceed the specified values, you need to install and eliminate the cause of contamination.

B. 7.4 Definition

Tin capsule (B. 5.2) is placed in a ceramic crucible (B. 5.3), slightly press it down, put it in a weighed test portion (B. 7.2) and covered with a flux (B. 4.5) in the amount of (1,5±0,1) g. the Crucible with the contents was placed on a special stand for crucibles, lead the device in the mode of combustion and closed combustion chamber. According to the instruction manual of the device include oven. At the end of combustion and measuring the crucible is removed and record the results of the analysis.

B. 7.5 preparing to build a calibration curve

B. 7.5.1 Samples with a mass fraction of sulfur less than 0.005%

B. 7.5.1.1 Preparation of the calibration solutions

Using a micropipette (B. 5.1) injected with 50 cmof water and each of the standard solutions of sulphur (table B. 2) four tin capsules. Then the solutions were slowly evaporated at 90 °C to complete drying, the capsule was cooled to room temperature and placed in a desiccator.


Table B. 2

B. 7.5.1.2 Measurement

Tin capsule, placed in a ceramic crucible (B. 5.3), slightly press it to the bottom of the crucible, add 1,000 g of pure iron (B. 4.2) and covered with a flux (B. 4.5) in the amount of (1,5±0,1) of the act, as specified in B. 7.4.

B. 7.5.1.3 Construction of calibration curve

From the measurement values found for each calibration solution, subtract the values obtained for the reference experiment. The calibration curve built according to the found thus the true values of indications of the scale and their corresponding values of sulphur in milligrams in each calibration solution.

B. 7.5.2 Samples with a mass fraction of sulfur from 0.005% to 0.04%

B. 7.5.2.1 Preparation of calibration solutions series

Using a micropipette (B. 5.1) injected with 50 cmof water and each of the standard solutions of sulphur (table B. 3) five tin capsules (B. 5.2). Then the solutions were slowly evaporated at 90 °C to complete drying, the capsule was cooled to room temperature and placed in a desiccator.


Table B. 3

B. 7.5.2.2 Measurement

The measurement is carried out according to B. 7.5.1.2

B. 7.5.2.3 Construction of calibration curve — B. 7.5.1.3.

B. 7.5.3 Samples with a mass fraction of sulfur from 0.04% to 0.1%

B. 7.5.3.1 Preparation of the calibration solutions

Using a micropipette (B. 5.1) to enter 100 cmof water and each of the standard solutions of sulphur (table B. 4) five tin capsules (B. 5.2). Then the solutions were slowly evaporated at 90 °C to complete drying, the capsule was cooled to room temperature and placed in a desiccator.


Table B. 4

B. 7.5.3.2 Measurement

Tin capsule, placed in a ceramic crucible (B. 5.3), slightly press it to the bottom of the crucible, add 0,500 g of pure iron (B. 4.2) and covered with a flux (B. 4.5) in the amount of (1,5±0,1) g. the Crucible and its contents must be processed as specified in B. 7.4.

B. 7.5.3.3 Construction of calibration curve — B. 7.5.1.3

B. 8 Processing of results

B. 8.1 the Calculation

Indications for the analyzed samples obtained on the scale of the instrument, transferred by using a calibration curve (B. 7.5.1) to the corresponding values of the mass fraction of sulfur () in milligrams.

Mass fraction of sulfur , %, is calculated by the formula

, (B. 2)

where is the mass of sulfur in the analyzed sample, mg;

the mass of sulphur in a control experiment, mg;

 — the weight of the portion of the sample,

B. 8.2 the accuracy of the method

The measurement accuracy in this method is characterized by the following metrological characteristics: repeatability (), intralaboratory reproducibility () and interlaboratory reproducibility ().

Between the mass fraction and sulfur , and in table B. 5, there is a logarithmic dependence.


Table B. 5

B. 9 test report

The test report must contain the following information:

— all the information about the laboratory and date of analysis;

— the method used with reference to this standard;

the results and the form in which expressed samples;

— any unusual features noted during the analysis;

— any operation not specified in this standard, or any activities which could affect the results of the analysis.

ANNEX b (informative). Technical features of induction furnaces and infrared analyzers manufactured for the determination of sulfur

THE APP
(reference)

B. 1 oxygen Source (cylinder or coloradobased) shall be fitted with a pressure reducing valve for regulating the pressure of oxygen fed into the furnace. The pressure regulator shall be designed to 28 kg/m.

V. 2 purification unit for oxygen consists of an absorption tube filled with asbestos impregnated with sodium hydroxide for carbon dioxide absorption, and drainage tube with the rate of sodium.

B. 3 gas flow Meter (rheometer), designed for measuring in the range 0−4 DM/min.

B. 4 high-Frequency induction furnace

V. 4.1 incinerator consists of an induction coil and high frequency oscillator. The furnace chamber is a silica tube (outer diameter 30−40 mm, inner diameter 26−36 mm, tube length of 200−220 mm), which is inserted inside the induction coil. On the ends of the tube are metal plates reinforced with metal rings. The plates have inlet and outlet openings for gas.

V. 4.2 high-Frequency generator with a capacity of 1.5−2.5 kW may have a different frequency depending on the specific manufacturer.

Used frequency: 2−6 MHz, 15 MHz or 20 MHz. Energy from the generator is supplied to an induction coil, which is placed in a silica tube, and cooled by air.

V. 4.3 Crucible with sample, submerged arc and flux are placed on a stand, positioned so that when lifting the metal in the crucible was directly inside an induction coil that provides effective communication when power is applied.

V. 4.4 the diameter of the induction coil the number of turns, the geometric dimensions of the furnace chamber and a power generator is determined by the manufacturer.

V. 4.5, the combustion Temperature depends on the factors referred to in V. 4.4, and the properties of the metal in the crucible, the shape and mass of the analyzed sample.

Q. 5 dust Collector, designed for cleaning current of oxygen leaving the furnace from dust and metal oxides.

V. 6 Infrared analyzer

V. 6.1 For most devices of this type it is characteristic that the gaseous products of combustion are transferred to the analyzer system continuous flow oxygen. The gas flow passes through a cell where the photocell detects the radiation absorbed by the sulphur dioxide in the infrared region of the spectrum, the radiation is measured and summed over a given period of time. The signal is converted into the percentage of sulfur and is displayed on the dial of the instrument.

V. 6.2 In some analyzers, the products of combustion are collected in an atmosphere of oxygen at a controlled pressure in a given volume, and this mixture is analyzed for sulfur dioxide.

V. 6.3, the Analyzer is typically supplied electronic devices for setting the instrument scale to zero, compensation for the idle experience, set the slope of the calibration curve and correction in case of its nonlinear character. In addition, the analyzer has, as a rule, the possibility of entering the mass of sample standard sample and a test sample for automatic correction of the read result. The devices can also be equipped with automatic scales for weighing of crucibles, samples and test portions of the subjects transfer values of their mass into the calculator.