GOST 8724-2002 Basic standards of interchangeability. Metric thread. Diameters and pitches (ISO 261-1998 ISO metric threads for general use - Diameters and pitches (NEQ))

82. Main dimensions of metric threads, mm (according to GOST 9150-81, GOST 8724-81, GOST 24705-81)

d, D are the outer diameters of the external thread (bolt) and internal thread (nut), respectively;

d2, D2 are the average diameters of the bolt and nut, respectively;

d1, D1 are the internal diameters of the bolt and nut, respectively;

d3 is the internal diameter of the bolt along the bottom of the cavity;

P - thread pitch;

H is the height of the original triangle.

The nominal values ​​of the thread diameters must correspond to those indicated in the drawing and in the table. Diameter values ​​are calculated using the following formulas:

H = 0.866025R.

D2 = D – 2(3/8)H = D – 0.649519053P

d2 = d -2(3/8) = d - 0.649519053Р;

D1 = D – 2(5/8)H = D – 1.082531755P;

d1 = d - 2(5/8)H = d - 1.082531755P;

d3 = d - 2(17/24)H = d - 1.226869322P.

Tolerances of metric threads (GOST 16093-81)

The standard applies to metric threads with a profile in accordance with GOST 9150-81, diameters from 1 to 600 mm in accordance with GOST 8724-81 and GOST 16967-81, main dimensions in accordance with GOST 24705-81 and GOST 24706-81 and establishes a system of tolerances and clearance fits.

The positions of the tolerance fields of external and internal threads are shown in Fig. 2, 3.

Deviations are measured from the nominal thread profile in the direction perpendicular to the thread axis.

Tolerances of thread diameters are established according to degrees of accuracy, indicated by numbers.

The degrees of accuracy and main deviations of diameters are given in table. 83, thread diameter tolerances - in table. 84.

Rice. 2 Positions of external thread tolerance fields:

a - with main deviations d, e, f, R; b - with main deviations h

Diameter tolerances d1 and D are not established.

Tolerances for the average thread diameter are cumulative.

The position of the thread diameter tolerance field is determined by the main deviations (upper es for external threads and lower EI for internal threads) and is designated by a letter of the Latin alphabet, lowercase for external threads and uppercase for internal threads.

The tolerance field of the thread diameter is formed by a combination of tolerance and basic deviation.

The thread tolerance field is formed by combining the average diameter field with the tolerance field of the diameter of the protrusions (diameters d or D\).

Designation of the thread diameter tolerance zone

consists of a number indicating the degree of accuracy and a letter indicating the main deviation.

For example, 4h; 6g; 6H.

The designation of the thread tolerance field consists of the designation of the tolerance field of the average diameter, placed in the first place, and the designation of the tolerance field of the diameter of the protrusions.

Main settings

Each thread has precise geometric parameters. Metric is characterized by a triangular thread profile, which is also called fastening. It is used for parts connected to each other by screwing. The profile size is determined by its height.

The profile height (H) is the segment from the base to the top of an equilateral triangle, which is formed by a transverse section of the coil. The protrusions and depressions are made in the form of triangles with cut off vertices. In some cases, the depressions are rounded.

If the sides of each turn are mentally extended to the point of their intersection, then they will form a profile angle (α).

Thread profile

The main parameters indicated in the designation of a metric thread characterize its size. These include diameter and pitch. Metric thread designations indicate the main parameters.

Thread diameter is divided into 4 types:

• outer;
• interior;
• average;
• nominal.

Thread parameters such as stroke (Ph) and pitch (P) are interdependent and equal for a single-start system.

Thread stroke and pitch

The section separating the points of the same name on two turns is the thread pitch. There are main steps (large) and small steps.

Thread lead is a segment connecting two identical points on adjacent turns of the same thread. In the case where there are several entries, the move is expressed through the product of the number of steps and the number of entries.

The main thread elements also include:

• A surface inclined 45º in front of the inner or behind the outer is called a chamfer. It plays a role in connecting elements.
• Run-off is the place of transition to the uncut surface of the part. These two indicators are united by length, that is, a segment with turns, chamfer and runoff.

For metric threads, the main dimensions are summarized in tables of the relevant standards: GOST 9150-2002, GOST 8724-2002, GOST 24705-2004.

Possible structural deviations caused by the properties of materials are reported by tolerance fields, with values ​​not exceeding the nominal profile formed by the maximum of the material. These indicators affect the accuracy of the thread fit - the density of penetration of the protrusions into the gaps.

Thread tolerance fields are divided into three accuracy classes. And also 4 types according to your preference.

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GOST 8724-2002
(ISO 261-98)

Group G13

INTERSTATE STANDARD

Basic norms of interchangeability

METRIC THREAD

Diameters and pitches

Basic norms of interchangeability. Metric screw threads. General plan

ISS 21.040.10

OKSTU 0071

Date of introduction 2004-01-01

Preface

1 DEVELOPED by the Research and Design Institute of Measuring Instruments in Mechanical Engineering (JSC NIIizmereniya)

2 INTRODUCED by Gosstandart of Russia

3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Protocol No. 22 of November 6, 2002)

The following voted for adoption:

4 This standard is identical to the international standard ISO 261-98 “ISO threads for general purposes. Diameters and pitches in the diameter range from 1 to 300 mm" and contains additional requirements reflecting the needs of the country's economy

5 By Decree of the State Committee of the Russian Federation for Standardization and Metrology dated June 23, 2003 N 201-st, the interstate standard GOST 8724-2002 (ISO 261-98) was put into effect directly as a state standard of the Russian Federation from January 1, 2004.

6 INSTEAD GOST 8724-81

Amendments have been made, published in IUS N 10 2004, IUS N 4 2006

1 area of ​​use

This standard applies to general-purpose metric threads with a profile in accordance with GOST 9150 and sets their diameters from 0.25 to 600 mm and pitches from 0.075 to 8 mm.

The main dimensions of metric threads are according to GOST 24705.

Thread tolerances are in accordance with GOST 9000 and GOST 16093.

Additional requirements reflecting the needs of the country's economy are shown in italics.

2 Normative references

This standard uses references to the following standards:

GOST 9000-81 Basic standards of interchangeability. Metric thread for diameters less than 1 mm. Tolerances

GOST 9150-2002 Basic standards of interchangeability. Metric thread. Profile

GOST 11708-82 Basic standards of interchangeability. Thread. Terms and Definitions

GOST 16093-70 Basic standards of interchangeability. Metric thread. Tolerances. Landings with clearance

GOST 24705-81 Basic standards of interchangeability. Metric thread. Main Dimensions

3 Definitions

Terms and definitions - according to GOST 11708.

4 Selection of diameters and pitches

4.1 The diameters and pitches of threads must correspond to those indicated in Table 1.

When choosing thread diameters, you should prefer the first row to the second, and the second to the third.

Table 1

In millimeters

Continuation of Table 1

In millimeters

Continuation of Table 1

In millimeters

Continuation of Table 1

In millimeters

End of table 1

In millimeters

5 Thread designations

5.1 The symbol for the thread size must include: the letter M, the nominal diameter of the thread and the thread pitch, expressed in millimeters and separated by the sign “x”.

Example: M8x1.25

A major pitch in the thread designation may be omitted.

Example: M8.

5.2 The symbol for left-hand threads must be supplemented with the letters LH.

Example М8х1-LH

5.3 Multi-start threads must be designated by the letter M, the nominal diameter of the thread, the sign x, the letters Ph, the thread lead value, the letter P and the pitch value.

An example of a symbol for a double-start thread with a nominal diameter of 16 mm, a stroke of 3 mm and a pitch of 1.5 mm:

M16xPh3P1.5

The same for left-hand thread:

M16xPh3P1.5-LH

For greater clarity, the number of thread starts may be indicated in parentheses in text.

Example: M16xPh3Р1.5 (two passes)

5.4 The full thread designation includes the designation of the size and tolerance fields of the thread in accordance with GOST 9000 or GOST 16093. Download the full version

Thread diameter

The conditional parameter used to designate threads in drawings and reference tables is called the nominal diameter.

If we describe an imaginary cylinder around the protrusions of the external thread and the cavities of the internal thread, then its diameter will be called external. And the designation on the drawings: D – for internal; d – for external.

The internal diameter is the size of the inscribed cylinder in the recesses of the external thread and at the points of the vertices of the internal thread, denoted by: D1 and d1 for internal and external, respectively.

The average diameter is a parameter of an imaginary cylinder whose segments are equal to ½ thread pitch. Designated: D2 and d2.

The internal diameter of the bolt is used to calculate the stress in the fastener. Its value can be taken from the table with diameters, or calculated independently based on the nominal value.

Geometric parameters

Let's consider the geometric parameters that characterize the main elements of metric threads.

• The nominal thread diameter is designated by the letters D and d. In this case, the letter D refers to the nominal diameter of the external thread, and the letter d refers to a similar parameter of the internal thread.
• The average diameter of the thread, depending on its external or internal location, is designated by the letters D2 and d2.
• The internal diameter of the thread, depending on its external or internal location, is designated D1 and d1.
• The inside diameter of the bolt is used to calculate the stresses created in the structure of such a fastener.
• The thread pitch characterizes the distance between the crests or valleys of adjacent threaded turns. For a threaded element of the same diameter, a basic pitch is distinguished, as well as a thread pitch with reduced geometric parameters. The letter P is used to denote this important characteristic.
• The thread lead is the distance between the crests or valleys of adjacent threads formed by the same helical surface. The progress of the thread, which is created by one screw surface (single-start), is equal to its pitch. In addition, the value to which the thread stroke corresponds characterizes the amount of linear movement of the threaded element performed by it per revolution.
• A parameter such as the height of the triangle that forms the profile of the threaded elements is designated by the letter H.

Geometric parameters of the main metric thread profile

Table of metric thread diameter values ​​(all parameters are indicated in millimeters)

Metric thread diameters (mm)

Complete table of metric threads according to GOST 24705-2004 (all parameters are indicated in millimeters)

Complete table of metric threads according to GOST 24705-2004

The main parameters of metric threads are specified in several regulatory documents.

GOST 8724
This standard contains requirements for the parameters of the thread pitch and its diameter. GOST 8724, the current version of which came into force in 2004, is an analogue of the international standard ISO 261-98. The requirements of the latter apply to metric threads with a diameter of 1 to 300 mm. Compared to this document, GOST 8724 is valid for a wider range of diameters (0.25–600 mm). At the moment, the current edition of GOST 8724 2002, which came into force in 2004 instead of GOST 8724 81. It should be borne in mind that GOST 8724 regulates certain parameters of metric threads, the requirements for which are also specified by other thread standards. The convenience of using GOST 8724 2002 (as well as other similar documents) is that all the information in it is contained in tables, which include metric threads with diameters within the above range. Both left-handed and right-handed metric threads must meet the requirements of this standard.

GOST 24705 2004

This standard stipulates what basic dimensions a metric thread should have. GOST 24705 2004 applies to all threads, the requirements for which are regulated by GOST 8724 2002, as well as GOST 9150 2002.

GOST 9150

This is a regulatory document that specifies the requirements for the metric thread profile. GOST 9150, in particular, contains data on what geometric parameters the main threaded profile of various standard sizes must correspond to. The requirements of GOST 9150, developed in 2002, as well as the two previous standards, apply to metric threads, the turns of which rise from the left upward (right-handed type), and to those whose helical line rises to the left (left-handed type). The provisions of this regulatory document closely echo the requirements given by GOST 16093 (as well as GOSTs 24705 and 8724).

GOST 16093

This standard specifies the tolerance requirements for metric threads. In addition, GOST 16093 prescribes how metric type threads should be designated. GOST 16093 in its latest edition, which came into force in 2005, includes the provisions of the international standards ISO 965-1 and ISO 965-3. Both left-hand and right-hand threads fall under the requirements of such a regulatory document as GOST 16093.

The standardized parameters specified in the metric thread tables must correspond to the thread dimensions in the drawing of the future product. The choice of the tool with which it will be cut should be determined by these parameters.

Thread pitch

The pitch can also be found from the thread table or from the markings. Threads can have a main pitch, also called coarse, and fine. Depends on the diameter of the product.

If it is more than 68 mm, then only small, different values ​​are used for such a surface. Having a diameter up to the specified value makes it possible to produce threads with both large and fine pitches.

Each diameter has its own coarse pitch, which is not indicated in the marking.

When attaching parts, it is important to know the pitch, otherwise it will lose strength. The step can be determined by instrumental or comparative methods, such as:

• measure with a thread gauge;
• compare by comparing the threads of different parts with each other;
• try to screw the external thread into the internal thread; there should be no resistance;
• Measure the stroke in millimeters with a caliper and divide the resulting value by the number of strokes.

Tolerance fields

The fit of the outer profile into the inner one depends on the working height - the maximum amount of contact between the sides of the profiles of the connecting elements. It is expressed through thread tolerance fields.

The reliability of the connection, where fluctuations within it are minimized, is indicated by the first or exact tolerance class. The most common is the second (middle) class. The third (rough) class indicates a large deviation.

Tolerances on the dimensions of metric threads are indicated through the values ​​of two diameters: the average and the diameter of the protrusions.

When forming a metric thread, data is taken from the corresponding tables (GOST 16093-2004). The selection of tolerance fields is carried out according to the rules of priority:

• first priority – values ​​indicated in bold;
• the second - in regular font;
• third – values ​​​​taken in parentheses;
• extraordinary – values ​​in square brackets (for special products).

It is possible to use tolerances that are not indicated in the tables, but are formed from the ratios of existing standard diameters.

External thread tolerance fields

Internal thread tolerance fields

It is important that the protective coatings of parts in their geometric parameters do not exceed the value of the nominal profile, therefore in such cases tolerances are used even before applying the protective layer.

Designation rules

To indicate the tolerance range of an individual metric thread diameter, a combination of a number is used, which indicates the accuracy class of the thread, and a letter, which determines the main deviation. The thread tolerance field should also be indicated by two alphanumeric elements: in the first place - tolerance field d2 (middle diameter), in the second place - tolerance field d (outer diameter). If the tolerance fields of the outer and middle diameters coincide, then they are not repeated in the designation.

Metric thread designation

According to the rules, the thread designation is affixed first, followed by the tolerance zone designation. It should be borne in mind that the thread pitch is not indicated in the markings. You can find out this parameter from special tables.

The thread designation also indicates which screw length group it belongs to. There are three such groups:

• N – normal, which is not indicated in the designation;
• S – short;
• L – long.

The letters S and L, if necessary, follow the tolerance zone designation and are separated from it by a long horizontal line.

Example designation of 24 mm threads of various types (according to GOST 8724)

It is also necessary to indicate such an important parameter as the fit of the threaded connection. This is a fraction formed as follows: the numerator contains the designation of the internal thread related to its tolerance field, and the denominator contains the designation of the tolerance field for external threads.

An example of a threaded connection fit designation in the drawings

Types of metric threads

Metric threads also mean all types with different profiles, measured in millimeters. These include:

• triangular thread;
• trapezoidal;
• rectangular;
• round.

In addition to the metric system for measuring parameters, the following are used:

• inch;
• modular, where the module is the ratio of the length, expressed in millimeters, to the number π;
• pitch, basic unit - pitch - the ratio of the number π to the length, expressed in inches.

Modular threads are used for worm gears in mechanical engineering, just like pitch threads. Inch and metric are fastening thread types, but can be used for transmission.

By location they are distinguished:

• internal;
• external

The internal thread is located in the hole, it is obtained with a tap, a specialized tool that is a rod with cutting edges.

Internal metric thread

External threads are made with a cutter or die on a rod. They can also be obtained by coasting on appropriate equipment.

External metric thread

The shape of the surface can be cylindrical or conical.

Metric conical thread is used for installation of pipelines. It is performed on surfaces where the larger diameter exceeds the small one by 16 times. Diameters vary from 6 to 60 mm.

They are also divided according to the direction of the turns into right and left. To determine the direction of the thread, it is necessary to position the part so that its axis is located away from the observer. Then, the right-hand thread is formed by a circle rotating from left to right with translational motion along the axis, and the left-hand thread, accordingly, counterclockwise.

There are different types of step sizes:

• large (with a main, large step);
• small (with small);
• special.

A large pitch is considered normal and is suitable for any materials, including fragile ones. Small allows you to withstand heavy loads, but the materials must have certain strength characteristics. Small and special ones are rarely used.

Large and fine thread pitch

The place of transition from a smooth surface to a helical one is called the approach. Based on their number, they are divided into: single- and multi-pass. The latter are also subdivided by the number of passes: two-, three- and multi-pass.

Another classification is by application. They are:

• fastening and thrust-fastening;
• kinematic or chassis;
• special purpose.

Below are the main types of metric threads and their letter designations:

• the capital letter "M" symbolizes the metric type,
• if it is made on the surface in the form of a cone, then “MK”;
• for conditions where heat resistance and strength are required, use the metric cylindrical “MJ”;
• according to ISO – “EG-M”;
• trapezoidal – “Tr”;
• persistent with an angle of inclination of one side of 30º – “S”;
• persistent reinforced - “S45”, where the number is the angle of inclination of one of the sides.

Application

Metric threads are widespread in the countries of the former Soviet Union. Used for application to both internal and external planes of fasteners. Typically used for fastening metal structures of various types. For these purposes, a variety of bolts (anchor and conventional) and other types of fasteners are manufactured. She found a particular purpose in mechanical engineering, construction of engineering communications, especially in the plumbing sector. Most pipe and container fittings are manufactured with this type of thread.

Most often, this type of carving is applied to cylindrical objects. But in some cases, when it is necessary to achieve tightness, a conical shape is used. This form, with a metric thread applied, allows you to achieve maximum tightness, even without the use of additional sealing agents. Most often used for installation of pipelines.

State standards

GOST 8724-2002

State standard containing standards defining the required parameters of metric threads, including pitch and diameter. Adopted in 2002, with subsequent editions, as an analogue of the international standard ISO 261-98. The GOST text practically repeats the international text, with one difference: the ISO range ranges from 1 to 300 mm, this standard has been expanded to the range from 0.25 to 600 mm. The last revision of the text was made in 2004 and is valid today.

The standard contains individual parameters that can also be found in other standards. The structure of the document is similar to other standards of this type. All information is structured in the form of tables containing requirements for thread pitch and diameter. This test structure is as convenient as possible for understanding and use.

Download GOST 8724-2002

It should be noted that the regulatory information applies to threads of all types, be it left-handed or right-handed. The standard establishes the standard value of metric thread steps in the range from 0.075 to 8 mm.

The document consists of:

• Prefaces. Which contains general information about GOST, by whom and when it was adopted, when changes were made.
• Scope of application. Information is provided on the range of regulatory requirements for size and pitch.
• Links to standards.
• Definitions.
• Table of diameters and pitch. The section contains a table of standard indicators.
• Thread designation. Labeling standards are indicated.

GOST 24705-2004

The standard was adopted in 2004. Its standards apply to all types of threads in accordance with GOST 8724. The text information is also structured in the form of a table. Complies with the international standard ISO 724:1993 with additions in accordance with the exclusive requirements of each member country of the Interstate Council for Standardization.

Download GOST 24705-2004

GOST 9150-2002

A standard regulating the requirements for the profile, namely the geometric parameters. Adopted in 2002 and covering all types of threads. The text of GOST is closely related to the above standards.

Download GOST 9150-2002

GOST 16093-2004

Adopted in 2004. Regulates the standard tolerance of threads and markings, applies to different types. The latest version contains the provisions of the international standard.

The above standards are applied in combination, as they complement and refer to each other.

Metric thread

BASIC DIMENSIONS OF METRIC THREAD (GOST 9150-2002, GOST 8724-2002, GOST 24705-2004)
GOST 8724-2002 is an identical text to the international standard ISO 261-98 “ISO threads for general purposes. Diameters and pitches in the diameter range from 1

up to
300
mm" and contains additional requirements reflecting the needs of the country's economy (up to 600 mm).

This standard applies to general purpose metric threads with a profile in accordance with GOST 9150 and sets their diameters from 0,25

up to
600
mm and steps from
0.075
to
8
mm. The main dimensions of metric threads are in accordance with GOST 24705. Thread tolerances are in accordance with GOST 9000 and GOST 16093.

where, d, D

— outer diameters of the external thread (bolt) and internal thread (nut), respectively;
d2, D2
are the average diameters of the bolt and nut, respectively;
d1, D1
are the internal diameters of the bolt and nut, respectively;
d3
is the internal diameter of the bolt along the bottom of the cavity (for calculating stresses);
p
—thread pitch;
H
is the height of the original triangle.

The nominal values ​​of thread diameters must correspond to those indicated in the drawing and table. The main threads with diameters from 2

up to
300
mm of the 1st and 2nd (in brackets) rows.
The full table is below. dimensions, mm

FULL TABLE OF METRIC THREADS according to GOST 24705-2004

Examples of thread designations:

with coarse pitch: the coarse pitch in the thread designation can be omitted

external thread: M12 x 1.75 - 6g

or
M12 - 6g;
internal thread:
M12 - 6H;
with small steps:

external thread: M12 x 1 - 6g;

internal thread:
M12 x 1 - 6H;
left hand thread:

external thread: M12 x 1 - LH - 6g;

internal thread:
M12 x 1 - LH - 6H;
multi-start thread:

external thread: M12 x Ph3.5P1.75 - 6g;

internal thread:
M12 x Ph3.5P1.75 - 6H;
For greater clarity, the number of thread starts can be indicated in parentheses in text:

M12 x Ph3.5P1.75 - 6H (two passes);
M16 x Ph4.5P1.5 - 6H (three passes).
Make-up length is the length of the area of ​​mutual overlap of external and internal threads in the axial direction. Make-up lengths are divided into three groups: short - S, normal - N and long - L. Make-up length N is not indicated in the thread symbol. Make-up lengths S and L may be supplemented by indicating the make-up length:

M12 - 6g - S

;
M12 - 6g - L
;
M12 - 6g - L - LH
;
M12 - 6g - L(30)
.

An example of the designation of a thread with a make-up length different from normal:

M12 - 7g6g - 30

The designation of the thread tolerance field consists of the designation of the tolerance field of the average diameter, placed in the first place, and the designation of the tolerance field of the diameter of the protrusions. If the designation of the tolerance field for the diameter of the protrusions coincides with the designation of the tolerance field for the average diameter, then it is not repeated in the designation of the thread tolerance field.

The fit in a threaded connection is indicated by a fraction, the numerator of which indicates the designation of the tolerance field of the internal thread, and the denominator indicates the designation of the tolerance field of the external thread.

For example:

M12 - 6H/6g;
M12 x 1 - 6H/5g6g; M12 x 1 - 6H/6g - LH.
More detailed thread designation can be found in GOST 9000-81

and
GOST 16093-2004
.

Below is a table for replacing the tolerance field according to previously valid standards.
REPLACING THREAD TOLERANCES

TOLERANCE FIELDS according to GOST 16093-2004
Tolerance fields are established in three accuracy classes: fine, medium and coarse:

— precise: for precision threads, when a small fluctuation in the nature of the fit is necessary; - medium: for general use; - rough: for cases where production difficulties may arise, for example, when cutting threads on hot-rolled rods or in long blind holes.

According to the degree of preference of choice, the tolerance fields in the tables are subdivided as follows:

— tolerance fields indicated in square brackets are selected for commercial fasteners; — tolerance fields typed in bold are intended to be selected first; — tolerance fields typed in light font are intended for selection in the second place; — the tolerance fields indicated in brackets are intended to be selected in the third place.

In justified cases, it is allowed to use thread tolerance fields formed by other combinations of tolerance fields of the average diameter and the diameter of the thread protrusions from those given in the tables or obtained by other combinations of degrees of accuracy and main deviations, for example: 4h6h; 8h; 8h6h - for external thread; 5H; 5N6N - for internal thread.

For threads with protective relatively thin coatings, for example with galvanic coatings, tolerances and maximum deviations according to the standard are applied to the dimensions of the parts before coating, unless otherwise specified. After coating, the actual thread profile at no point should not exceed the nominal thread profile (the maximum material profile corresponding to the main deviation h or N).

The fits can combine any tolerance fields for external and internal threads from those recommended. However, to ensure sufficient working height of the profile, the final dimensions of the threaded connection parts must form fits of type H/g, H/h and G/h. For threads with dimensions M1.4 and smaller, fit 5H/6h should be selected. 4H/6h or more precisely.

Related documents:

— holes for threading GOST 3469-91 — Microscopes. Lens thread. Dimensions GOST 4608-81 - Metric thread. Interference fits GOST 5359-77 - Ocular threads for optical instruments. Profile and dimensions GOST 6042-83 - Edison round thread. Profiles, dimensions and maximum dimensions GOST 6111-52 - Conical inch thread with a profile angle of 60 degrees GOST 6211-81 - Conical pipe thread GOST 6357-81 - Cylindrical pipe thread GOST 8762-75 - Round thread with a diameter of 40 mm for gas masks and calibers for her. Main dimensions GOST 9000-81 - Metric thread for diameters less than 1 mm. Tolerances GOST 9484-81 - Trapezoidal thread. Profiles GOST 9562-81 - Single-start trapezoidal thread. Tolerances GOST 9909-81 - Tapered thread of valves and cylinders for gases GOST 10177-82 - Persistent thread. Profile and main dimensions GOST 11708-82 - Thread. Terms and definitions GOST 11709-81 - Metric thread for parts made of plastic GOST 13535-87 - Reinforced thrust thread 45 degrees GOST 13536-68 - Round thread for sanitary fittings. Profile, main dimensions, tolerances GOST 16093-2004 - Metric thread. Tolerances. Clearance fits GOST 16967-81 - Metric threads for instrument making. Diameters and pitches GOST 24737-81 - Single-start trapezoidal thread. Main dimensions GOST 24739-81 - Multi-start trapezoidal thread GOST 25096-82 - Persistent thread. Tolerances GOST 25229-82 - Metric conical thread GOST 28487-90 - Conical locking thread for drill string elements. Profile. Dimensions. Tolerances