GOST 5781-82

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  ГОСТ 5781-82

GOST 5781−82 hot-rolled Steel for reinforcement of concrete structures. Technical specifications (with Changes N 1, 2, 3, 4, 5)

GOST 5781−82
Group B22

INTERSTATE STANDARD

HOT-ROLLED STEEL FOR REINFORCEMENT OF CONCRETE STRUCTURES

Specifications

Hot-rolled steel for reinforcement of ferroconcrete structures. Specifications

ISS 77.140.15

OKP 09 3004; 3005 09; 09 3006;
09 3007; 3008 09

Date of introduction 1983−07−01

INFORMATION DATA

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

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 17.12.82 N 4800

3. REPLACE GOST 5.1459−72, GOST 5781−75

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

The designation of the reference document referenced	Item number
GOST 380−2005	2.3, 2.4
GOST 2590−2006	1.6
GOST 7564−97	4.5
GOST 7565−81	3.4
GOST 7566−94	3.2, 3.6, 5.1
GOST 9454−78	4.8
GOST 12004−81	4.6
GOST 12344−2003	4.1
GOST 12348−78	4.1
GOST 12350−78	4.1
GOST 12352−81	4.1
GOST 12355−78	4.1
GOST 12356−81	4.1
GOST 14019−2003	4.7
GOST 18895−97	4.1
OST 14−34−78	Annex 2

5. Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

6. EDITION (Sept 2009) with Changes in N 1, 2, 3, 4, 5, approved in February 1984, June 1987, December 1987, October 1989, December 1990 (5−84, 11−87, 3−88, 1−90, 3−91)


This standard applies to hot-rolled round steel smooth and periodic profile, designed for conventional reinforcement and prestressed concrete structures (reinforcing steel).

As part of the rules of the chemical composition of low alloy steels standard also applies to bars, blooms and billets.

(Changed edition, Rev. N 4).

1. CLASSIFICATION AND ASSORTMENT

1.1. Depending on the mechanical properties of the reinforcing steel is subdivided into classes A-I (A240), A-II (A300), A-III (A400); A-IV (A600), A-V (A800), A-VI (A1000).

1.2. Manufactures reinforcing steel in bars or rolls. Reinforcing steel of class A-I (A240) is made smooth, classes A-II (A300), A-III (A400), A-IV (A600), A-V (A800) and A-VI (A1000) — periodic profile.

On demand of the consumer steel of classes A-II (A300), A-III (A400), A-IV (A600), and A-V (A800) to produce smooth.

1.1, 1.2. (Changed edition, Rev. N 5).

1.3. Profile numbers, the cross sectional area, weight of 1 m length of reinforcing steel smooth and periodic profile, as well as maximum deviations by mass for periodic structures should correspond to those in table.1.

Table 1

The profile number (nominal diameter of the bar )	The cross-sectional area of core, cm	Weight of 1 m of the profile
Theoretical, kg	Limit. off %
6	0,283	0,222	+9,0
8	0,503	0,395	-7,0
10	0,785	0,617	+5,0 -6,0
12	1,131	0,888
14	1,540	1,210
16	2,010	1,580	3.0 a -5,0
18	2,540	2,000
20	3,140	2,470
22	3,800	2,980
25	4,910	3,850
28	6,160	4,830
32	8,040	6,310	3.0 a -4,0
36	10,180	7,990
40	12,570	9,870
45	15,000	12,480
50	19,630	15,410	+2,0 -4,0
55	23,760	18,650
60	28,270	22,190
70	38,480	30,210
80	50,270	39,460

(Changed edition, Rev. N 3).

1.4. The nominal diameters of periodic structures should correspond to nominal diameters equal to the cross sectional area of smooth profiles.

1.5. Weight of 1 m calculated with nominal size at a density of steel equal 7,85·10kg/m. The likelihood of reaching the mass of 1 m should be not less than 0.9.

(Changed edition, Rev. N 3).

1.6. Limit deviations of the diameter of the smooth structures must comply with GOST 2590 for the usual accuracy of rolling.

1.7. Reinforcing steel periodic profile is a circular profile with two longitudinal edges and cross ledges, going for a triple-threaded helical line. For profiles with a diameter of 6 mm allowed the ribs going on a single helix with a diameter of 8 mm around the double helix.

1.8. Reinforcement steel of class A-II (A300) made in the ordinary performance, the profile is given on features.1A, and a special purpose As-II (Ac300) profile given on features.2A, should have tabs running along the helical lines with the same length on both sides of the profile.

Damn.1

Damn.2

Steel class A-III (A400), made the profile given on features.1B and class A-IV (A600), A-V (A800), A-VI (A1000) profile given on features.1B, 2B, should have tabs on the helical lines, with one side of the right profile, and with another — the left calls.

Reinforcing steel special purpose class AC-II (Ac300) produce profiles given on features.1A or 2A.

The profile given on features.2A, a special purpose are made by agreement between manufacturer and consumer. The shape and dimensions of the profiles given on features.2A, b, can be specified.

1.9. Dimensions and limit deviations of the dimensions of reinforcing steel periodic profile, which is manufactured by the devil.1A, b, shall be as given in table.2, and for God.2A, b are given in table.3.

1.10. The relative displacement of screw ledges on the sides of the profile, divided by longitudinal edges, off-standard.

Dimensions that have not installed limit deviations, given to build the caliber and the finished profile is not checked.

1.11. Circle of smooth structures (difference of largest and smallest diameters in the same cross section) shall not exceed the sum of the positive and negative limit deviation for diameter.

1.9−1.11. (Changed edition, Rev. N 3).

1.12. Reinforcing steel of classes A-I (A240) and A-II (A300) with a diameter of 12 mm and class A-III (A400) diameters up to 10 mm incl. manufactured in coils or rods of large diameter in rods. Reinforcing steel of classes A-IV (A600), A-V (A800) and A-VI (A1000) all sizes are made in rods with diameter of 6 and 8 mm, in agreement with the consumer in rolls.

1.13. The rods are manufactured in length from 6 to 12 m:

— the measured length;

— measuring length with non-standard segments with a length of not less than 2 m not more than 15% by weight of the party;

— random length.

The party of bars with variable length is allowed in bars with length from 3 to 6 m, not more than 7% by weight of the party.

Table 2

Dimensions in mm
The profile number (nominal diameter )
Nomin.	Pred. off.	Nomin.	Pred. off.
6	5,75	+0,3 -0,5	0,5	±0,25	6,75	0,5	5	0,5	1,0	0,75
8	7,5	0,75	9,0	0,75	0,75	1,25	1,1
10	9,3	1,0	±0,5	11,3	1,0	7	1,0	1,5	1,5
12	11,0	1,25	13,5	1,25	2,0	1,9
14	13,0	15,5
16	15,0	1,5	18,0	1,5	8	1,5	2,2
18	17,0	20,0
20	19,0	22,0
22	21,0	+0,4 -0,5	24,0
25	24,0	27,0
28	26,5	+0,4 -0,7	2,0	±0,7	30,5	2,0	9	2,5	3,0
32	30,5	34,5	10	2,0	3,0
Thirty six	34,5	2,5	39,5	2,5	12	3,5
40	38,5	43,5
45	43,0	3,0	49,0	3,0	15	2,5	3,5	4,5
50	48,0	54,0
55	53,0	+0,4 A 1.0	±1,0	59,0	4,0
60	58,0	64,0	5,0
70	68,0	+0,5 -1,1	74,0	4,5	5,5
80	77,5	83,5
Note. At customer’s request, maximum deviations in size shall not exceed extreme deviations plus double limit deviation .

By agreement with the consumer it is allowed manufacture of cores from 5 to 25 m.

1.14. Maximum deviations on length of rods shall be as given in table.4.

Table 3

Dimensions in mm
The profile number (nominal diameter )
Nomin.	Pred. off.	Nomin.	Pred. off.
10	8,7	+0,3 -0,5	1,6	±0,5	11,9	1,6	0,6	1,0	10	0,7	1,5	11	50°
12	10,6	13,8	2,0
14	12,5	2,0	+0,65 -0,85	16,5	2,0	0,8	1,2	12	1,0	2,0	12
16	14,2	2,5	19,2	2,5	1,0	1,5
18	16,2	21,2
Twenty	18,2	23,2
22	20,3	+0,4 -0,5	25,3
25	23,3	28,3	14	1,2	14
28	25,9	+0,4 -0,7	3,0	+1,0 -1,2	31,9	3,0	1,2	1,8	2,5
32	29,8	3,2	36,2	3,2	2,0	16	1,5	3,0	19
36	33,7	3,5	40,7	3,5	1,5	18
40	37,6	44,6

Table 4

Length of rods, m	Pred. off. along the length with a precision of cutting, mm
normal	high
To 6 incl.	+50	+25
SV. 6	+70	+35

The rods of the increased accuracy produce on demand of the consumer.

1.15. The curvature of the rods should not exceed 0.6% of the measured length.

Examples of symbols

Reinforcing steel with a diameter of 20 mm, class A-II (A300):

20-A-II GOST 5781−82

The same, with a diameter of 18 mm, class A-I (A240):

18-A-I GOST 5781−82

In the notation of cores of a class A-II (A300) special purpose add the index «C»: AC-II (Ac300).

(Changed edition, Rev. N 4).

2. TECHNICAL REQUIREMENTS

2.1. Reinforcing steel manufactured in accordance with the requirements of this standard for technological regulations approved in the prescribed manner.

2.2. Reinforcing steel is made from carbon and low-alloy steel grades specified in table.5. The steel grade indicates the consumer is in order. If you have not specified the grade of steel sets the manufacturer. For rods of the class A-IV (A600) of the steel grade is determined by agreement between manufacturer and consumer.

Table 5

Grade of reinforcing steel	The diameter of the profile, mm	Steel grade
A-I (A240)	6−40	St3kp, St3ps, St3sp
A-II (A300)	10−40	St5sp, St5ps
40−80	18G2S
As-II (Ac300)	10−32 (36−40)	10GT
A-III (A400)	6−40	35GS, 25G2S
6−22	32g2rps
A-IV (A600)	10−18 (6−8)	80S
10−32 (36−40)	20KHG2C
A-V (A800)	(6−8) 10−32 (36−40)	23KH2G2T
A-VI (A1000)	10−22	22KH2G2AJU, 22KH2G2R, 20KH2G2SR
Notes: 1. Allowed fabrication of reinforcing steel of class A-V (A800) of steel grades 22KH2G2AJU, 22KH2G2R and 20KH2G2SR. 2. Dimensions shown in parentheses are made by agreement between manufacturer and consumer.

(Changed edition, Rev. N 3, 4).

2.3. Chemical composition of reinforcing carbon steel shall meet the requirements of GOST 380, low alloy steels — standards, shown in table.6.

Table 6

Steel grade	Mass fraction of elements, %
Carbon	Manganese	Silicon	Chrome	Titan	Cubic Zirconia	Aluminium tions	Nickel	Sulfur	Phosphorus	Copper
no more
10GT	Not more than 0.13	Of 1.00 to 1.40	0,45−0,65	Not more than 0.30	0,015- 0,035	-	0,02- 0,05	-	0,040	0,030	0,30
18G2S	0,14−0,23	1,20−1,60	0,60−0,90	-	-	0,30	0,045	0,040
32g2rps	0,28−0,37	1,30−1,75	Not more than 0,17	0,001- 0,015	0,050	0,045
35GS	0,30−0,37	0,80−1,20	0,60−0,90	-	0,045	0,040
25G2S	0,20−0,29	1,20−1,60
20KHG2C	0,19−0,26	1,50−1,90	0,40−0,70	0,90−1,20	0,05−0,14	0,045
80S	0,74−0,82	0,50−0,90	0,60−1,10	Not more than 0.30	0,015- 0,040	-	0,040
23KH2G2T	0,19−0,26	1,40−1,70	0,40−0,70	1,35−1,70	0,02- 0,08	0,015- 0,050	0,045
22KH2G2AJU	1,50−2,10	0,005- 0,030	0,02- 0,07	0,040	0,040
22KH2G2R	1,50−1,90	1,50−1,90	0,02- 0,08	0,015- 0,050
20KH2G2SR	0,16−0,26	1,40−1,80	0,75−1,55	1,40−1,80

2.3.1. In steel brand 20KHG2C allowed the increase of the mass fraction of chromium to 1.7% replacement of zirconium 0.02−0.08% of titanium. In steel brand 23KH2G2T may be replaced with titanium of 0.05 to 0.10% zirconium. In this case, in the designation of the steel grade 20KHG2C instead of the letter C, the letter T, steel grade 23KH2G2T instead of the letter T, the letter C.

In steel brand 32g2rps permitted to replace aluminum with titanium or zirconium in equal units.

2.3.2. Mass fraction of nitrogen in steel grade 22KH2G2AJU should be 0,015−0,030%, mass fraction of residual nitrogen in steel 10GT — no more than 0,008%.

2.3.3. Mass fraction of boron in steel grades 22KH2G2R, 20KH2G2SR and 32g2rps should be 0,001−0,007%. In steel brand 22KH2G2AJU allowed the addition of boron 0,001−0,008%.

2.3.4. It is allowed to add titanium to steel 18G2S brands, 25G2S, 35GS from the calculation of its mass fraction in the finished rolled 0,01−0,03%, in steel grade 35GS from the calculation of its mass fraction in the finished rolled products made in rolls, of 0.01−0.06%.

2.4. Deviations in chemical composition in the ready-rolled carbon steels — the churchyard 380, of low-alloy steels in compliance with standards mechanical properties — in table.7. The negative deviation in the concentration of elements (except titanium and zirconium, and for steel grades 20KH2G2SR — silicon) limit.

Table 7

Elements	Pred. off %
Carbon	+0,020
Silicon	+0,050
Manganese	+0,100
Chrome	+0,050
Copper	+0,050
Sulfur	+0,005
Phosphorus	+0,005
Cubic Zirconia	+0,010 -0,020
Titan	±0,010
Note. By agreement between manufacturer and consumer steel can be manufactured with other disabilities on the content of chromium, silicon and manganese.

(Changed edition, Rev. N 3).

2.5. Reinforcing steel of classes A-I (A240), A-II (A300), A-III (A400), A-IV (A600) manufactures hot-rolled, class A-V (A800) — with low-temperature vacation, class A-VI (A1000) — with low-temperature vacation or thermomechanical processing in the flow rolling mill.

Allowed not to leave low-temperature steel of classes A-V (A800) and A-VI (A1000) subject to obtaining the elongation is not less than 9% and a uniform elongation of not less than 2% when tested within 12 hours after rolling.

2.6. Mechanical properties of reinforcing steel must conform to the standards specified in table.8.

For steel of class A-II (A300) with a diameter of over 40 mm permitted a reduction of the elongation by 0.25% for every millimeter increase in diameter, but not more than 3%.

For steel grade As-II (Ac300) allowed the reduction of temporary resistance to 426 MPa (43.5 kgf/mm) at a relative elongation of 30% or more.

For steel grade 25G2S class A-III (A400) may reduce strength to 560 MPa (57 kgf/mm) at yield not less than 405 MPa (41 kgf/mm), relative elongation not less than 20%.

Table 8

Grade of reinforcing steel	Yield strength		Rupture strength		Take tive. - use , %	Same- measuring elongation- use , %	Toughness at minus 60 °C		The bend test in cold state (thickness mandrel  — diameter rod)
N/mm	kgf/mm	N/mm	kgf/mm	MJ/m	kgf·m/cm
not less than
A-I (A240)	235	24	373	38	25	-	-	-	180°; =
A-II (A300)	295	30	490	50	19	180°; =3
As-II (Ac300)	441	45	25	0,5	5	180°; =
A-III (A400)	390	40	590	60	14	-	-	90°; =3
A-IV (A600)	590	60	883	90	6	2	45°; =5
A-V (A800)	785	80	1030	105	7
A-VI (A1000)	980	100	1230	125	6
Notes: 1. By agreement with the consumer allowed to test on the impact strength of reinforcing steel class As-II. 2. (Deleted, Rev. N 3). 3. For reinforcing steel of class A-IV with a diameter of 18 mm and steel stamps 80C rate of cold bending is set not less than 30°. 4. For reinforcing steel of class A-I (A240) with a diameter of over 20 mm for cold bending 180° =2, class A-II (A300) with a diameter of over 20 mm =4. 5. In brackets denote the class of reinforcing steel for yield strength.

(Changed edition, Rev. N 1, 3, 5).

2.7. Statistical parameters of mechanical properties of rods of reinforcing steel periodic profile shall conform to Annex 1, with high homogeneity of mechanical properties — Annex 1 and table.9.

The probability of obtaining mechanical properties specified in table.8 should be not less than 0.95.

(Changed edition, Rev. N 3).

2.8. On the surface of the profile, including the surface edges and protrusions, must not be rolled cracks, cracks, stress, flaws, rolling and captured the sunset.

Allowed minor damage on edges and ledges, not more than three per 1 m of length, and minor rust, separate, rolled, dirt, fingerprints, flows, traces, rolled, bubbles, Rabina and scaliness within the variation permitted in size.

(Changed edition, Rev. N 2).

2.9. Weldability of reinforcing steel of all grades, in addition to 80S, provided the chemical composition and manufacturing technology.

2.10. Carbon equivalent for the welded rod reinforcement steel class A-III (A400) should be no more than 0,62.

(Added, Rev. N 5).

Table 9

Grade of reinforcing steel	Room profile
For ()	For	For ()	For	For ()	For	For ()	For
MPa (kgf/mm)		MPa (kgf/mm)
no more
A-II (A300)	10−40	29 (3)	29 (3)	15 (1,5)	15 (1,5)	0,08	0,06	0,05	0,03
A-III (A400)	6−40	39 (4)	39 (4)	20 (2,0)	20 (2,0)	0,07
A-IV (A600)	10−32	69 (7)	69 (7)	39 (4,0)	39 (4,0)	0,09	0,06	0,05
A-V (A800)	78 (8)	78 (8)	49 (5,0)	49 (5,0)
A-VI (A1000)	88 (9)	88 (9)	0,08	0,05	0,04
Notes: 1.  — standard deviation in the population of trials;  — standard deviation in the party-smelting;  — the average value in the General set of tests;  — the minimum average value in the batch-melting process. 2. For reinforcing steel in coils with a diameter of 6 mm and 8 mm allowed increase in regulations and 4.9 MPa (0.5 kgf/mm). 3. (Deleted, Rev. N 5).

3. ACCEPTANCE RULES

3.1. Reinforcing steel can take parties composed of profiles of the same diameter, one class, one melting ladle and drawn up by one document on quality.

The mass of the party must be up to 70 t

Allowed to increase the weight of the batch to the weight of the melting-ladle.

3.2. Each batch is accompanied by a quality document according to GOST 7566 with additional data:

room profile;

class;

— the minimum average value and average quadratic deviation in the party of values () and ;

— results of flexure tests in cold condition;

values of uniform elongation for steel of class A-IV (A600), A-V (800), A-VI (A1000).

3.3. To check dimensions and surface quality are taken:

— in the manufacture of reinforcing steel rods not less than 5% of the party;

— in the manufacture in rolls — two rolls from each batch.

(Changed edition, Rev. N 3).

3.4. To check the chemical composition of the samples are taken according to GOST 7565.

Mass fraction of aluminium, the manufacturer specifies periodically, but not less than once per quarter.

3.5. To check tensile, Flexural and impact strength of the party taken two rods.

For the factory interval selection rods should not be less than half the time spent rolling one profile size one of the party.

(Changed edition, Rev. N 3).

3.6. If unsatisfactory test results of at least one of the indicators, repeat tests carried out according to GOST 7566.

4. TEST METHODS

4.1. Chemical analysis were carried out according to GOST 12344, 12348 GOST, GOST 12350, 12352 GOST, GOST 12355, 12356 GOST, GOST 18895 or other methods providing the required accuracy.

4.2. The diameter and the roundness profiles measured at a distance of not less than 150 mm from the end of the bar, or at a minimum distance of 1500 mm from the end of a coil with a coil weight up to 250 kg and not less than 3000 mm at a mass skein over 250 kg.

4.3. The size check of the measuring tool necessary accuracy.

4.4. From each selected terminal to test tensile, bending and impact strength, cut off one sample.

4.5. Sampling for tests of tensile, bending and impact strength is carried out according to GOST 7564.

4.6. The tensile test is carried out according to GOST 12004.

4.7. The bend test is carried out according to GOST 14019 on samples with cross-section equal to the cross section of the rod.

For rods with a diameter of over 40 mm are allowed the test specimens, cut along the axis of the rod, the mandrel diameter is reduced twice in comparison with the specified in table.4, with a bending side of the cut.

4.8. Impact strength testing is carried out according to GOST 9454 on samples with a hub U type 3 for rods with a diameter of 12−14 mm and the samples of type I, for rods with a diameter of 16 mm and more. The samples manufactured in accordance with the requirements of GOST 9454.

4.9. Allowed to apply statistical methods and non-destructive control of mechanical properties and mass profiles.

4.10. The curvature of the rods is measured on the length of the supplied profile, but not shorter than 1 m.

4.11. Definition of statistical indicators of the mechanical properties in accordance with Annex 2.

4.12. The surface quality test without the use of magnifying devices.

4.10−4.12. (Added, Rev. N 3).

4.13. The height measurement of the transverse protrusions periodic profile should be on the vertical axis of the cross section of reinforcing bars.

(Added, Rev. N 4).

5. PACKING, MARKING, TRANSPORTATION AND STORAGE

5.1. Packing, marking, transportation and storage — by GOST 7566 with the following additions:

the ends of the rods of low-alloy steels of the class A-IV (A600) should be painted with red paint, class A-V red and green, class A-VI (A1000) — red and blue. Allowed coloration of ligaments at a distance of 0.5 m from the ends;

— the rods are Packed in bundles weighing up to 15 t, tied with wire or catalkoy. At the request of the consumer, the rods are Packed in bundles weighing up to 3 and 5 t

On the ligaments the paint is applied in strips with a minimum width of 20 mm on the lateral surface of the circle (½ circumference) at a distance of not more than 500 mm from the end.

On Hanks paint is applied in strips with a minimum width of 20 mm across the turns of the outside coil.

For unpackaged products, the paint is applied to the end face or lateral surface at a distance of not more than 500 mm from the end.

On the label attached to each bundle of rods, put the symbol for a class of reinforcing steel (e.g. A-III), or the symbol class for yield strength (A400).

(Changed edition, Rev. N 3, 5).

ANNEX 1 (mandatory). REQUIREMENTS FOR STATISTICAL MEASUREMENT OF MECHANICAL PROPERTIES

ANNEX 1
Mandatory

1. The manufacturer guarantees the consumer the middle values of temporary resistance and yield strength (physical and notional ) in the General population — and the minimum average values of the same indicators in each batch-melting — whose values are sets of conditions:

;

;

,

where  — rejection values , given in table.8 of this standard;

 — the value of the quantile is assumed equal to 2 for classes A-II (A300) and A-III (A400) and 1.64 — classes A-IV (A600), A-V (A800) and A-VI (A1000).

2. Quality control of characteristic values of mechanical properties of products in the factory

2.1. Required indicators of quality profiles provide the technology and production control test according to the requirements of section 3.5, PP.4.4−4.8.

2.2. The values , , and installed in accordance with the test results and Annex 2.

3. Quality control of characteristic values of mechanical properties of products in the enterprise, the consumer

3.1. A consumer document on the quality of products of the highest quality may not conduct tests of mechanical properties.

3.2. If you want to check the mechanical properties of each batch of six test samples taken from different packages or skeins and from different profiles, and the results of checking the conditions:

;

,

where  — the average value of mechanical properties the test results of six samples;

 — the minimum value of test results of six samples.

3.3. Minimum values of elongation and uniform elongation shall not be less than the values given in table.8.

(Changed edition, Rev. N 3, 5).

ANNEX 2 (mandatory). The method of determining the statistical indicators of the strength characteristics of mechanical properties of hot-rolled steel for reinforcement of concrete structures

ANNEX 2
Mandatory

This methodology applies to hot-rolled, accelerated-cooled, thermo-mechanical and heat-strengthened rolled periodic profile, manufactured in reels or rods.

The methodology used in the reliability estimation of mechanical properties of each batch-smelting and steel in General, the stability control of the process.

1. To determine statistical characteristic values of mechanical properties (yield stress physical or conditional , temporary tear resistance ) use control test results, called the General populations.

2. Compliance the mechanical properties of rolled with the requirements of normative-technical documentation is determined on the basis of statistical processing of test results constituting the sample of the General population. All findings, results and conclusions made on the basis of sampling, refers to the entire General population.

3. Sample — a set of results of the control tests forming the data array to be processed.

The sample includes the results of commissioning tests of the hire of the same class, same brand and production methods, laminated on single or group of close sizes of sections.

4. The sample on the basis of which calculate the statistical indicators should be representative and cover a sufficiently long period of time, but not less than 3 months during which the process has not changed. If necessary, the period of time for sampling can be increased. Checking the homogeneity of the sample — according to normative-technical documentation.

5. A number of parties-heats in each sample should be at least 50.

6. The sample selection must comply with the condition of random sampling from the batch-melting. Assessment of abnormality of test results carried out according to normative-technical documentation.

7. The aggregation to determine the average value , the standard deviation of each sample (whole population), medium quadratic deviation within the party-bottoms , and the standard deviation plenochnykh medium . The amount determined by the formula

.

Value , determined by normative-technical documentation.

8. Check the consistency of the characteristics and carried out in accordance with OST 14−34.

9. The value determined for the rapidly-cooled, thermo-mechanical and heat-hardened reinforcing steel only experimental method for HR — experimental method and method of the scale according to the formula where and are respectively the mean value and srednekvadraticheskogo deviation of the distribution scale on the two tests from the party.

The minimum value is 1.

10. Determination of the experimental method is carried out on at least two batches for each steel grade, class, and profilemaster rental by random selection of at least 100 samples from each heat.

11. The minimum average values of the strength characteristics ((), ) in each batch-melting is determined from the condition where  — the value of the quantile of 1.64 for the probability of 0.95.

12. The minimum value of the results of tensile tests on two samples (=2) each lot under inspection shall be not less than determined by the formula

.

13. To provide assurance to the consumer of mechanical properties should be satisfied the following conditions:

;

;

,

where is the acceptance value () and specified in the relevant normative technical documentation.

Appendix 2. (Added, Rev. N 3).