GOST 14311-85

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  ГОСТ 14311-85

GOST 14311−85 Steel. Specifications (with Amendments No. 1, 2, 3)

GOST 14311−85

The Group Of 75

INTERSTATE STANDARD

Steel CORD

Specifications

The Steel cord. Specifications

ISS 77.140.65
OKP 12 7900

Date of introduction 1987−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 16.07.85 N 2245

3. REPLACE GOST 14311−77

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

________________

* The document is not given, here and hereafter. For additional information, please refer to the link. — Note the manufacturer’s database.

5. The expiration time limit is removed by the Resolution of Gosstandart of the USSR from 20.06.91 N 923

6. EDITION with Amendments No. 1, 2, 3, approved in October 1987, February 1990, June 1991 (ICS 1−88, 5−90, 9−91)


This standard applies to steel cord for the reinforcement of tires and other rubber products.

(Changed edition, Rev. N 2).

1. BASIC PARAMETERS AND DIMENSIONS

1.1. Steel cord shall be manufactured types 4Л22, 4Л22А, 9Л15/27, 9Л15/27A, 22Л15, 22Л15А, 28Л18, 28Л18А, 29Л18/15, 29Л18/15A, 40Л15, 40Л15А.

(Changed edition, Rev. N 1).

1.2. Construction, diameter, key size and parameters shall be as specified in table.1.

Examples of callouts

Steel cord with a diameter of 1.20 mm design (7x3)x0. 15+1x0. 15 of the brass plated wire with a diameter of 0.15 mm:

m/KORD 1,20−22Л15 GOST 14311−85

Steel cord with a diameter of 0.83 mm construction (1h3)x0. 15+6х0,265 index And of the brass plated wire with diameter 0,15 and 0,265 mm:

m/0,83 cord-9Л15/27A GOST 14311−85

Table 1

Note. Steps of lay of strands, the core and the steps of winding braiding wire is given in Annex 1.


(Changed edition, Rev. N 1, 2).

2. TECHNICAL REQUIREMENTS

2.1. Steel cord shall be manufactured in accordance with the requirements of this standard for technological regulations approved in the prescribed manner.

Steel cord shall be made of steel brassed wire diameter and ultimate strength, which to the lay in steel cord must conform to the standards given in table.2.

Table 2

The gap with the node of the wire should be not less than 55% of the breaking strength of the same wire when tested without a knot, and wire used for the manufacture of steel cord with the index And not less than 57%.

Rupture strength of wire braiding 1860 N/mm(190 kgf/mm) — 2840 N/mm(290 kgf/mm).

The wire produced from wire rod of higher quality according to normative-technical documentation.

(Changed edition, Rev. N 1).

2.2. Breaking strength of steel cord as a whole and its bonding strength with rubber must conform to the standards given in table.1.

2.3. Elongation at break of the steel cord with the index And shall not be less than 2% for other types of steel cord is not less than 1%.

2.4. Steel cord shall be manufactured of the cross lay (direction of the steel cord lay and direction of lay of the strands, the opposite). The direction of the steel cord stranding and braiding wire must be opposite. Steel cord types 4Л22, 4Л22А made helical lay. By agreement with the consumer it is allowed manufacture of steel cord unilateral lay.

2.3, 2.4. (Changed edition, Rev. N 1).

2.5. Strands of steel cord and steel cord must not have creases, perekrostok and dangling wires.

2.6. The connection of wires, strands and core in metallokorda should be performed by site or by welding. The ends of the connected wires and strands should be cut off. The length of the residual ends should not exceed 2 mm.

Allowed connection of the external wires and strands in metallokorda method of coiling and then joins host or by firmware. The distance between the ends of the firmware of the wires and strands should be no more than 1 m. the Rupture strength in place of the firmware should be at least 80% of the values given in table.1.

2.7. The connection of the segments should be of steel cord splice may be used, or butt welding. The number of connections per length of steel cord on one reel and length to couple the pusher must conform to the standards given in table.3.

Table 3

The distance between the individual joints shall not be less than 30 m. the Ends schallibaum wires and strands must be cut, the length of the residual ends must not exceed 3.5 mm.

The diameter of the steel cord at the connection should not exceed more than 0.5 mm of the nominal diameter shown in table.1.

Breaking strength at the weld shall not be less than 40% of the values given in table.1.

The lack of the brass cover in the case of electric welding is allowed on the length of not more than 10 mm.

2.6, 2.7. (Changed edition, Rev. N 1).

2.8. In places of connection of wires, strands, and segments of steel cord allowed deviation from the set winding step of braiding the wire, step lay steel cord and laying of wires and strands of a value not exceeding four steps.

2.9. Cut finished length of steel cord and limit deviations of length should conform to the standards given in table.4.

Table 4

(Changed edition, Rev. N 1).

2.10. On the surface of the steel cord should be free of dirt and corrosion. Allowed the presence of technological lubricant does not reduce the bond strength with rubber.

The norm for the mass fraction of the lubricant shall be enforced from 01.01.94.

(Changed edition, Rev. N 1, 3).

2.11. Steel cord should be straight, prescripcialis and have a length of 6 m to no more than three residual torsions for steel cord with the index and not more than four for metal cord.

(Changed edition, Rev. N 3).

2.12. The number of cycles that must withstand the steel cord during the test of endurance, and the diameter of the removable roller probizhna machine given in table.5.

Table 5

(Changed edition, Rev. N 1).

2.13. Estimated weight of steel cord are given in Appendix 2.

2.14. Mass fraction of copper in the brass coating should be (67±3)% for steel cord with the index A, (67±5)% for steel cord of other types. The norms for the mass fraction of copper in the brass coating steel cord with the index And introduced with effect from 01.01.96 for other steel cord types — from 01.01.93.

2.15. Mass of brass coating shall be (5±2) g/kg of steel cord. The norm weight of brass coating is introduced with effect from 01.01.96.

2.14, 2.15. (Changed edition, Rev. N 3).

2.16. (Deleted, Rev. N 2).

3. ACCEPTANCE RULES

3.1. Steel cord is adopted by the parties. Party the manufacturer should consist of steel cord of the same type produced during a shift. For the party the consumer accept the steel cord of the same type, delivered at a time. The party must be issued a document about quality that contains:

trademark or the name and trademark of manufacturer;

batch number;

designation of steel cord;

the results of the tests;

the date of manufacture of steel cord;

weight (net) party.

(Changed edition, Rev. N 1, 2).

3.2. The appearance test is subjected to each coil steel cord.

3.3. To check the geometric parameters, design of steel cord take one coil from each drum of the party.

(Changed edition, Rev. N 1).

3.4. To check the residual torsion, the straightness, neraskruchennosti, mechanical properties and bond strength with rubber selected 10% of the coils from the party, but at least two coils.

3.5. To check the endurance of steel cord, the mass fraction of copper in the brass coating, brass coating mass, the mass fraction of the lubricant and the length of the steel cord taken one spool of 40 barrels.

Check the mass fraction of copper in the brass coating and the weight of brass coating is carried out periodically 1 time per week.

Check the mass fraction of the lubricant is carried out periodically 2 times a month.

3.6. If unsatisfactory test results of at least one of the indicators it is carried out re-testing at twice the sample. Upon receipt of unsatisfactory results, re-testing the manufacturer carries out control of each packaging party place of the manufacturer, the results are final.

3.5, 3.6. (Changed edition, Rev. N 1, 2).

4. TEST METHODS

4.1. An external inspection of the steel cord is carried out visually.

4.2. Wire diameter is measured with a clamp according to GOST 11098 with a scale division of 0.002 mm or micrometer according to GOST 4381 according to GOST 6507 with a scale division of 0.01 mm, and the diameter of the steel cord with a micrometer according to GOST 6507 with a scale division of 0.01 mm in two mutually perpendicular directions of the same cross-section in at least three places.

The measurement result should be the arithmetic mean of six measurements. Measurement of the diameter of steel cord types 22Л15, 22Л15А, 40Л15, 40Л15А, 29Л18/15, 29Л18/15A is carried out without braiding the wire and to the obtained value is added the value of twice the nominal diameter of braiding wire.

4.3. The step lay the steel cord is measured at a distance of not less than 5 m from the end, wound on a spool, a caliper according to GOST 166 or ruler according to GOST 427.

To define the pitch of lay for steel cord is applied to the sheet of paper, tightly pressed it to metallokorda and at the place of contact of paper with the strands or wires hold the side of the stylus the pencil; on paper should get prints of the strands or wires of the outer layer of steel cord. Choose the station with the clearest prints. On one of the prints mark, which counts the number of prints equal to three times the number of strands or wires in the outer layer of steel cord and at the last imprint of the stamp. The distance between the prints, divided into three, would be a step lay steel cord.

Length of steel cord is controlled by the rewind.

4.4. Breaking strength of steel cord is determined on the sample without braided wire length of 1 m cut from each selected coil. To prevent unwinding of the sample and the steel cord on the spool the ends of their must be fixed by fusing or other means.

The test is carried out on a tensile testing machine according to the scale of loads with a maximum force not exceeding the breaking strength of the steel cord more than 5 times. The distance between clamps must be (225±25) mm. the steel cord Sample should be fixed on a tensile testing machine with grippers, which ensure reliable fixing. The loading rate of the active capture should be (60±10) mm/min.

A sample is considered satisfactory if the breaking strength of the steel cord meets the requirements of this standard no matter in what place there was a gap. If the tear occurred closer than 50 mm from the point of fixation of the specimen and breaking strength below the requirements of the standard, repeat tests are carried out.

4.5. Elongation is determined according to the method given in Appendix 3.

4.6. The test of steel cord on the bond strength with rubber carried out on samples in the form of two rubber bands connected by steel cord samples (Fig.1). Sample of steel cord cut from each selected coil. To prevent unwinding of the sample and the steel cord on the spool the ends of their must be fixed by fusing or other means.

Damn.1

Damn.1

Calender sheets (3,5) and (5,5) mm raw rubber compound type 2E-1155, manufactured according to normative-technical documentation, cut into strips with a width of 9−10 mm; strip thickness (3,5) mm is placed in a heated form (Fig.2), across they placed samples of steel cord, on which are placed strips of rubber with a thickness of (5,5) mm. allowed the use of rubber of the same thickness (4,5) mm.

Damn.2

Damn.2

After laying rubber and steel cord form close lid, set between the plates of a press maintained at a temperature of (142±3) °C, measured by the potentiometer press with an error of 0,5% for 45 minutes under a load of at least 2.5 N/mm(0,25 kgf/mm). Testing of samples is carried out one day after vulcanization. Allowed manufacturers to reduce the exposure time after curing up to 10 hours.

The test is performed by pulling out the steel cord from the rubber block on a tensile testing machine according to the scale of loads not more than five times the value of adhesion is given in table.1, with the loading rate of the active capture (100±10) mm/min. For fixing the samples on a tensile testing machine used special holders (Fig.3).

Damn.3

Damn.3

As a result of the strength test of connection of steel cord with rubber taking the arithmetic average of the four measurements from each check the coil.

4.7. Test for residual torsion and straightness is carried out on one sample. Before the test steel cord length 3 m unwound from the coil, is fixed to prevent rotation and cut. Not allowed unwinding the steel cord by dropping it through the coil cheek. You should then bend the cord at a right angle at a distance of 20 mm from the end. This bend should be rigidly fixed during the unwinding of the sample from the coil at a length of 6 m. the Free end of the steel cord sample is free. The number of revolutions of the steel cord believe, accurate to 0.5 of a turn.

After that, the sample length of 6 m is placed with no tension on the plane between two parallel lines located at a distance of (75±5) mm from each other. Steel cord is considered to be rectilinear if it is for 6 m length lies in the plane and is located within an area bounded by parallel lines, the intersection of any line with the free end of steel cord length of 0.5 m is not taken into account.

The deviation from plane of not more than 10 mm.

(Changed edition, Rev. N 1).

4.8. (Deleted, Rev. N 1).

4.9. To check steel cord for prescriptivist it is cut with a sharp instrument with a single pressure. While the end of the steel cord should not untwist in the individual strands and wire to more than one step lay.

(Changed edition, Rev. N 1, 2).

4.10. The test of steel cord of endurance is carried out according to GOST 2387 with additions:

the test is carried out without braided wire;

the mass of the load is chosen so that the load on the branch of a sample steel cord was 5% of the breaking strength shown in table.1;

settings groove replacement roller should conform to the values:

 — depth: 3±0.20 mm;

 — width of 1.8±0.20 mm;

 — the radius of curvature of 0.58±0.10 mm;

 — diameter of steel cord, mm

.

4.11. Allowed application of the method of statistical control of quality of steel cord, as set out in Annex 4.

(Changed edition, Rev. N 1).

4.12. Determination of the mass fraction of copper and the weight of brass coating is carried out according to the method described in Annex 5, or via another method providing the same accuracy and certified in the prescribed manner.

(Added, Rev. N 1).

4.13. Determination of the mass fraction of the lubricant carried out according to the method, certified in the prescribed manner.

(Added, Rev. N 3).

5. PACKING, MARKING, TRANSPORTATION AND STORAGE

5.1. Steel cord is wound onto the previously cleaned coil manufactured according to normative-technical documentation. The inner end of the steel cord is fixed to the coil in such a way to allow free spooling of steel cord from the reel; not allowed consolidation of the node. Winding the steel cord on the reel should be smooth, dense, without the entanglement and to permit free unwinding the steel cord. Cheek of the coil must project beyond the outer layer of steel cord winded at least 3 mm.

5.2. Coil with steel cord are placed in tightly closed barrels made according to normative-technical documentation. Coils in barrels shall be secured to preclude damage to the cheeks of the coil and the packing density of the steel cord during loading and unloading.

Laying of coils in the barrel should allow for dredging of all coils with a metal cord at the same time conveying mechanism.

5.3. To absorb moisture in every barrel put silica gel according to GOST 3956 at the rate of 1 kg at 1 m, Packed in bags of a fabric according to GOST 29298, or other similar fabrics.

By agreement with the consumer allowed the use of other substances according to normative-technical documentation, are equivalent in their moisture-absorbing properties and do not influence on the quality parameters of the steel cord.

5.4. On the label put in each barrel shall be stated:

trademark or a trademark and the name of the manufacturer;

designation of steel cord;

batch number.

On each barrel shall contain:

trademark or a trademark and the name of the manufacturer;

designation of steel cord;

batch number;

weight (gross).

date of manufacture of steel cord;

manipulation sign «Protect from moisture»;

the letter O for steel cord unilateral lay.

5.3, 5.4. (Changed edition, Rev. N 1, 2).

5.5. Transport marking under GOST 14192.

5.6. And steel is transported by all types of transport in covered vehicles in accordance with cargo carriage regulations applicable to transport of this form, and the technical conditions of loading and fastening of cargoes, approved by the Ministry of Railways of the USSR.

5.7. Storage steel cord — according to GOST 15150, conditions 1. Allowed storage of the drums in the two tiers without breaking the packing density.

5.6; 5.7. (Changed edition, Rev. N 1).

5.8. Barrels for transportation and storage shall be in a vertical position.

6. MANUFACTURER’S WARRANTY

6.1. The manufacturer guarantees the quality of steel cord with the requirements of this standard if the conditions of transportation and storage.

6.2. Warranty period of storage of the steel cord 4 months from date of manufacture.

ANNEX 1 (reference). The steps of stranding core, the core strands and the steps of winding braiding wire

ANNEX 1
Reference

APPENDIX 1. (Changed edition, Rev. N 1, 2).

ANNEX 2 (informative). Estimated weight of 1 m steel cord

ANNEX 2
Reference

APPENDIX 2. (Changed edition, Rev. N 1).

APPENDIX 3 (obligatory). TEST ELONGATION AT BREAK STEEL CORD

APPENDIX 3
Mandatory

1. Equipment and materials

Tensile testing machine, ensuring the stop of the movable gripper of the machine, at the moment of sample breakage.

Sample of steel cord with a length of 800−900 mm without braiding wire.

2. Preparation and testing

The test sample is loaded with a preliminary load of 10% of the established standard minimum breaking strength of steel cord as a whole.

The readings of the drum scale elongation set at 0.

The speed of the movable grip should be (60±10) mm/min.

Load a sample to destruction.

Take readings of the scale at the moment of rupture of the specimen.

3. Processing of the results

Elongation () in percent is calculated by the formula

,

where  — the lengthening of the sample, recorded on the scale, mm;

 — the initial length of the specimen equal to the distance between the grips, mm.

APPENDIX 4 (recommended). METHOD FOR STATISTICAL QUALITY CONTROL OF STEEL CORD

ANNEX 4
Recommended

These methods establishes sampling plans for quality control of the steel cord and the criteria for decisions on acceptance or rejection of the party.

The main purpose of statistical quality control is to reduce the cost of monitoring while ensuring the required level of product quality.

1. Steel cord take parties in accordance with clause 3.1 of this standard.

2. Upon acceptance of the steel cord shall be subjected to external inspection, control the geometric parameters, the residual torsion, straightness, mechanical properties, bond strength with rubber, endurance, mass fraction of copper and the mass of brass coating, the mass fraction of lubricant, the length of the steel cord, neraskruchennosti.

3. Steel cord for control should be selected randomly from different places of the party.

4. Install the main control — normal according to GOST 18242*.
____________
* On the territory of the Russian Federation GOST R 50779.71−99 (here and below).

5. To control the geometrical parameters define the diameter limit deviation for diameter steps lay steel cord.

Control of the geometric dimensions, neraskruchennosti, straightness, and residual torsion should be carried out by a single-stage plan, with the level of control-4 level and acceptance quality level of 1% according to GOST 18242.

6. When controlling mechanical properties determine the breaking strength of the steel cord, the elongation at break.

Control of mechanical properties should be carried out by a single-stage plan, with the level of control-4 level and acceptance quality level of 1% according to GOST 18242.

7. Under the control of the adhesive properties of the steel cord determine the bond strength with rubber.

Control bond strength with rubber must be conducted by a single-stage plan, with the level of control-4 level and acceptance quality level of 0.65% for the GOST 18242.

8. During the test of steel cord strength and control the mass fraction of copper, the mass of brass coating, the mass fraction of the lubricant determine the number of cycles of loading given in table.5 of this standard.

Tolerance assessment is conducted by a single-stage plan, with the level of control-1 and the acceptance quality level of 1.5% according to GOST 18242.

9. The values of the sample size depending on the lot size, acceptance and rejection numbers under the control of geometrical dimensions, adhesion and mechanical properties are given in table.1, in the evaluation of stamina control the mass fraction of copper, the mass of brass coating, the mass fraction of the lubricant and the length of the steel cord — in table.2.

Table 1

Control of the geometric dimensions, neraskruchennosti, straightness, and residual torsion,
mechanical properties and bond strength of steel cord with rubber

Table 2

Control of endurance of steel cord, the mass fraction of copper, the mass of brass coating,
the mass fraction of the lubricant and the length of the steel cord

10. The results of the quality control of steel cord party shall be considered accepted if the number of samples with deviations in the sample is less than or equal to the acceptance number and is rejected if the number of samples with deviations in the sample is greater than or equal to the acceptance number .

11. If unsatisfactory test results of at least one of the indicators it is carried out re-testing in accordance with PP.1−10. Sampling in this case should be from the coils not being tested.

If unsatisfactory results of repeated tests carried out the control of each packaging.

ANNEX 4. (Changed edition, Rev. N 1, 3).

APPENDIX 5 (mandatory). The method of measuring the mass fraction of copper in the brass coating and the mass of brass coating on metallokorda

ANNEX 5
Mandatory

The method of measuring the mass fraction of copper in the brass coating and the mass of brass coating on metallokorda.

This methodology establishes the procedure of measuring the mass fraction of copper in the brass coating and the mass of brass coating on metallokorda.

Controlled range: 50−90% of copper in a brass coating; a 3.0−9.0 g of brass per 1 kg of the cord.

The technique is intended to control the quality of brass coating on metallokorda.

1. METHOD OF MEASUREMENT

1.1. The method of determining the composition of the coating based on the formation of blue coloured complex compound of Amiata copper. Brass coating is dissolved from the surface of the cord a dilute solution of ammonia in the presence of oxidizing agents. The color intensity of the copper-ammonia complex is measured on a photoelectrocolorimeter. Zinc definition, does not prevent.

1.2. Gravimetric method for determining the weight of brass coating is based on the weighted samples of the cord on an analytical balance before and after coating removal.

2. MEASURING INSTRUMENTS, REAGENTS, SOLUTIONS

Photoelectrocolorimeter or spectrophotometer any brand with all accessories.

Analytical scale according to GOST 24104*.
______________
* From 1 July 2002 was put into effect GOST 24104−2001.

Watch sandy on the EAST 25−11−38 2, 3, 10 min.

Volumetric flasks according to GOST 1770, with a capacity of 50 cm, 100 cm.

Pipette glass for NTD, with a capacity of 1, 2, 5, 10 cm.

State standard samples (GSO) copper, brass.

Ruler according to GOST 17435.

Micrometer according to GOST 6507.

Ammonium persulfate according to GOST 20478.

Ammonium hydroxide according to GOST 3760, a density of 0.900 g/cmand diluted 1:1.

Nitric acid according to GOST 4461, diluted 1:1.

Sulfuric acid according to GOST 4204, diluted 1:1.

Ammonium sulfate according to GOST 3769, solution with the mass concentration of 110 g/DM.

Chromic anhydride according to GOST 3776, solution with the mass concentration of 275 g/DM.

Filter paper according to GOST 12026.

The technical rectified ethyl alcohol according to GOST 18300.

The aviation gasoline according to GOST 1012 (grade B-70).

Petrol is a solvent for paint industry (white spirit) according to GOST 3134.

Trichloroethylene according to GOST 9976.

Acetone according to GOST 2603.

Carbon tetrachloride according to GOST 20288.

Cleaning material such as cotton.

3. PREPARATION FOR MEASUREMENT

3.1. Preparation of the test solution to remove the brass when determining its composition: 10 g of ammonium persulfate dissolved in 500 cmof distilled water, adding 75 cmof concentrated ammonium hydroxide and diluted with distilled water to a volume of 1000 cm. The shelf life of the solution is not more than 5 days.

3.2. Preparation of a standard copper solution: 1 g of metallic copper (GSO) is dissolved in 25 cmof nitric acid (1:1), boil to remove oxides of nitrogen, cool, add 20 cmof sulphuric acid (1:1) and evaporated until the appearance of white fumes of sulfuric acid. After cooling, precipitated salts are dissolved in water when heated and transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix thoroughly. Mass concentration of copper in the standard solution is equal to 0.001 g/cm. A standard solution is prepared similarly to brass.

3.3. Construction of calibration curve

Five volumetric flasks with a capacity of 100 cmmeasured to the standard copper solution in the amount of 6, 9, 12, 15, 18 cm, which corresponds to 0,006; 0,009; 0,012; 0,015; 0.018 g of copper. Sixth bulb is used for the control solution. All flasks are poured 30 cmof the test solution, heated to boiling and boiled for 3 minutes in the hourglass. Cooled, added to 10 cmof ammonia solution 1:1, adjusted to the mark with water and mix.

Optical density of the solution measured on photocolorimetry in the region of wavelengths 630−675 nm with a red filter. Solution comparison is the control solution not containing standard copper solution. On the found values of optical density of the solutions and their corresponding masses of copper to build the calibration graph. Construction of calibration curve performed daily.

3.4. Preparation of the solution for determining the weight of the brass

500 cmof a solution of ammonium sulfate is combined with 500 cmof a solution of chromic anhydride and stirred. A sustainable solution is applied repeatedly.

3.5. Sampling and sample preparation

Determination of the mass fraction of copper in the brass and the mass of brass coating on the lunge is performed in two parallel measurements, i.e., four samples of the cord taken from the coil one after the other.

Approximately 1 m of the cord from the end of the controlled coil cut off and discarded. For each parallel measurements are taken sequentially samples the recommended cord length, which is specified in the table.1.

Table 1

Note. The cord samples are degreased by wiping cleaning rags soaked in one of the specified in paragraph 2 of the organic solvents and dried in a drying oven at (100±5) °C for 5 min.

Samples of the cord is designed to determine the coating mass, taking apart. Twist the wire into a ring or spiral.


(Changed edition, Rev. N 3).

4. MEASUREMENTS

4.1. Determination of the mass fraction of copper in brass

The cord samples are weighed on an analytical balance. Placed compactly in a glass with a capacity of 200 cm, fill 30 cmof the test solution and the brass is dissolved under stirring for 2 min the Solution was quantitatively transferred to a volumetric flask with a capacity of 100 cm, the sample and the Cup three times washed with water and the washings are attached to the main solution.

A sample of the cord in a glass rinsed with acetone or alcohol, dried with filter paper, dried in an oven at (100±5) °C for 10 min and weighed again.

The mass difference between the first and second weighings is the weight of brass taken for analysis.

Solution in a volumetric flask carefully heated to boiling and then do as stated in claim 3.3.

Solution comparison in the measurement of optical density is the solution of the reference experiment.

4.2. Determination of the mass of brass coating on the lunge

Samples of unwound cord in the form of segments of wire, rings or spirals are weighed on an analytical balance. The samples are placed in a spacious glass, fill them completely with a solution of chromic anhydride and ammonium sulphate (see p.3.4) with stirring. After 2 minutes the solution is decanted. The sample was washed with water, then solvent, dried in an oven at (100±5) °C for 10 min and weighed again. The mass difference between the first and second weighings is the mass of brass coating on the lunge.

(Changed edition, Rev. N 3).

5. PROCESSING OF THE RESULTS

5.1. Mass of copper in grams found by the calibration schedule. Allowed to determine the mass of copper by comparing the optical density of the sample solution with the optical density of a standard solution of brass. Mass of copper () in grams is calculated by the formula

,

where is the mass in a particular volume of standard solution, g;

 — optical density of the solution of the investigated samples;

 — optical density of standard solution.

Mass fraction of copper () in brass plated in percent is calculated by the formula

,

where is the mass (weight) of brass coating, taken from nerazvedennogo cord,

5.2. Mass of brass coating (a) in grams per 1 kg of the cord is calculated by the formula

,

where is the mass of the wire before removing the coating, g;

 — the mass of wire after removing the coating,

5.3. General requirements to ensure the accuracy of analysis results

5.3.1. For the analysis used reagents qualifications not lower than h. d. a. and distilled water according to GOST 6709.

5.3.2. When fotomaterialy of the cell are selected so that the measurements were carried out at the optimum optical density for the corresponding colored connections and this device.

5.3.3. The calibration graphs are built in rectangular coordinates. On the horizontal axis lay the mass of the element in grams on the y — axis optical density.

5.3.4. Calibration curve building not less than five points, distributing them evenly throughout the range of the designated concentrations.

5.3.5. For the results analysis be the arithmetic mean of results of two parallel measurements of two samples of the cord.

5.3.6. The numerical results of the analysis should be terminated with a figure the same category as that of the corresponding error value .

(Changed edition, Rev. N 3).

5.3.7. (Deleted, Rev. N 3).

6. NORMS OF ACCURACY OF MEASUREMENTS

Norms of accuracy and norms monitoring of the accuracy of measuring the mass fraction of copper in the brass coating and the mass of brass coating on the lunge shown in table.2.

Table 2

Designations:

 — the standard deviation of a random component of measurement error that characterize the interlaboratory reproducibility of measurements;

 — the limit of possible values of error of measurement results for a confidence level of 0.95;

 — the permissible discrepancy between two results of analysis of one sample obtained in different conditions;

 — permissible differences between results of two parallel measurements;

 — permissible difference of the result of the analysis of a standard solution from the certified values;

 — the value of the area precontrol the results of the analysis of normalized close to the border.


(Changed edition, Rev. N 1, 3).

7. OPERATIONAL CONTROL OF MEASUREMENT ACCURACY

7.1. Control the accuracy of the results of the analysis of the composition of brass is carried out on standard solution (CP) of copper, prepared according to state standard samples (GSO) of copper or brass.

Accuracy control measurement of coating mass is performed on a segment of wire uncoated diameter of 0.15−0.27 mm and weighing not less than 0.5 g.

7.2. Operational control of accuracy of analysis results is performed at least once per shift or simultaneously with the production group of samples.

7.3−7.5. (Deleted, Rev. N 3).

8. SAFETY REQUIREMENTS

When performing tests, it is necessary to observe the basic rules of safe work in the chemical laboratory*, which are set out in the relevant NTD, duly approved.
________________
* On the territory of the Russian Federation the document is not valid. Acts PND f 12.13.1−03. — Note the manufacturer’s database.

The text of the document is verified by:
the official publication of the
Wire metal. Part 2: Sat. Standards. -
M.: IPK Publishing house of standards, 2003