Bolts are the main fasteners for prefabricated structures. With the help of them, cars, machine tools, aircraft, bridges and buildings are assembled. They are used in household appliances and a variety of electrical appliances. Whether screwed into blind holes or used in conjunction with nuts, they create strong and reliable connections. The special configuration of the hex head makes it easy to tighten the bolts either by hand or with wrenches and hex sockets. To speed up the assembly and disassembly process, a wide variety of devices have been created, such as wrenches, ratchets, electric and pneumatic wrenches.

The most common in industry and engineering are, which consist of a stud and a hex head. The reference length, which is also indicated on the site, is the length of the hairpin without taking into account the height of the head.

They are available with metric threads from M6 to M48 and lengths from 8 mm to 300 mm. The standard provides for the production of bolts with fine and coarse (main) threads. Depending on the length, the thread is not completely cut, which reduces its cost and increases the strength of the stud as a whole.

Bolt materials GOST 7798 70

They are manufactured in medium accuracy class B, which has a small deviation in thread sizes and tolerances, and is also less expensive to manufacture.

Bolts are made from various materials:

• carbon steel;
• stainless steel;
• non-ferrous alloys;
• polyamide.

For use in aggressive environments, bolts are taken from stainless and acid-resistant steels. The difference is that an aggressive environment, unlike moisture, quickly destroys the protective coating, and the metal of the bolt is even faster. Non-ferrous metal hardware is used in specific operating conditions or devices. They have anti-magnetic properties and are not subject to corrosion.

Bolts are available in various strengths from 5.6 to 10.9, which is indicated on the head. High strength is not always the best option for a threaded connection. The specification requires the strength of the bolt to be slightly less than the strength of the threaded hole or nut with which it is used. For example, if the nut has a property class of 9, then the bolt must correspond to a property class of 8.8.

Protective coatings for bolts GOST 7798 70

Coatings are applied for the sole purpose of preserving the bolt geometry for as long as possible and maximizing its service life. The durability and functionality of the bolt will depend on how high-quality the protective coating will be.

Factors affecting the formation of rust, which destroys the metal, violating the profile of the thread and head, rendering the bolt unusable:

• atmospheric influence;
• high humidity;
• temperature fluctuations.

Hardware, which are made of ordinary carbon steel, are produced with an anti-corrosion coating. The most common coatings are:

• zinc;
• cadmium;
• oxide;
• phosphate;
• pewter;
• copper;
• zinc;
• silver;
• nickel.

If the bolt corrodes while in a threaded connection, it will be very difficult to unscrew it during repair or replacement. The thread of the bolt sticks to the thread on the nut or in the hole, and the head loses its hexagonal shape, which makes it difficult to grip it with a wrench.

Zinc protective coating is simple and inexpensive to manufacture, so it has become the most common for a variety of hardware. Zinc coatings differ somewhat in the method and method of application. The most common ones are:

• galvanized zinc;
• thermal diffusion galvanizing;
• hot galvanizing.

Zinc coating is available in two colors: white and yellow. The color of the coating does not affect the quality and durability and depends on the method of applying zinc.

In the manufacturing industry, bolts with protective coatings are widely used:

• oxide impregnated with oil;
• phosphate impregnated with oil.

They are mainly used for the assembly of machine tools, assemblies, assemblies and they are easy to distinguish in appearance, as they are of a characteristic black color. In this regard, no additional metal is applied to the bolt; they are cheaper than galvanized ones, but less resistant to moisture.

The standard allows the manufacture of bolts without any coatings (as is). They are much cheaper, but can only be installed in places where there is no exposure to moisture or parts will eventually be painted.

Buy bolt GOST 7798 70

The website of the online store has a large selection bolts GOST 7798 70. Here you can choose bolts of any strength, both coated and uncoated. If required, you can purchase bolts of the same size, but in different designs. The company's warehouses have a sufficient number of finished products to instantly satisfy even large wholesale orders.

Fill out an application on the Internet yourself, or contact the managers who will give more detailed information, take an order or arrange delivery.

• 1. This standard applies to hexagon head bolts of accuracy class B with thread diameters from 6 mm to 48 mm.
  The standard fully complies with ST SEV 4728-84.
  (Revised edition, Rev. No. 4).
• 2. The design and dimensions of the bolts must correspond to those indicated in the drawing and in table. 12. (Revision, Rev. No. 2-6).
• 3. Thread - in accordance with GOST 24705. Thread run-out and undercut - in accordance with GOST 27148. Bolt ends - in accordance with GOST 12414. (Changed edition, Amendment No. 5).
• 3a. The radius under the head - according to GOST 24670.
• 3b. Tolerances of dimensions, deviations of the shape and location of surfaces and control methods not established by this standard are in accordance with GOST 1759.1.
• 3c. Permissible bolt surface defects and control methods - according to GOST 1759.2. 3a - 3c. (Introduced additionally, Rev. No. 4).
• 4. (Deleted, Rev. No. 4).
• 5. Head options are set by the manufacturer.
• 5a. It is allowed to manufacture bolts with a diameter of the smooth part of the rod d 1
  approximately equal to the average thread diameter.
  (Introduced additionally, Rev. No. 3).
• 5 B. It is allowed to make bolts of executions 1 and 2 with a hole on the end surface of the head for applying marking marks with dimensions that do not reduce the strength of the head, while the depth of the hole should be no more than 0.4k. (Introduced additionally, Rev. No. 5).
• 6. Technical requirements - according to GOST 1759.0.
• 7. (Deleted, Rev. No. 2).
• 8. The mass of bolts is specified in appendix 1.

Notes:

• 1. Bolt sizes enclosed in brackets are not recommended.
• 2. It is allowed to manufacture bolts with the dimensions specified in Appendix 2.

Notes:

• 1. Bolts with length dimensions enclosed in brackets are not recommended.
• 2. Bolts, for which the values ​​of b are located above the broken line, are allowed to be made with a thread length up to the head.

An example of a symbol for a bolt of version 1 with a thread diameter d=12 mm, with a turnkey size S=18 mm, a length l=60 mm, with a large thread pitch with a tolerance field of 6g, strength class 5.8, uncoated:
Bolt M12 - 6gx60.58 (S18) GOST 7798-70
The same, execution 2, with turnkey size S = 19 mm, with a fine thread pitch with a tolerance field of 6g, strength class 10.9, made of steel grade 40X, with coating 01 6 microns thick:
Bolt 2M12x1.25 - 6gx60.109.40X.016 GOST 7798-70

INFORMATION DATA

• 1. DEVELOPED AND INTRODUCED by the Ministry of Ferrous Metallurgy of the USSR DEVELOPERS I. N. Nedoviziy, Ph.D. tech. sciences; B. M. Rigmant; V. I. Mokrinsky, Ph.D. technical sciences
• 2. APPROVED AND PUT INTO EFFECT by the Decree of the Committee of Standards, Measures and Measuring Instruments under the Council of Ministers of the USSR dated 04.03.70 No. 270
• 3. The standard fully complies with ST SEV 4728-84 4. INSTEAD OF GOST 7798-62
• 6. The limitation of the validity period was removed according to protocol No. 5-94 of the Interstate Council for Standardization, Metrology and Certification (IUS 11-12-94)
• 7. REPUBLICATION with Amendments No. 2, 3, 4, 5, 6, approved in February 1974, March 1981, March 1985, March 1989, July 1995 (IUS 3-74, 6-81 , 6-85, 6-89, 9-95)

Weight of steel bolts (version 1) with a large thread pitch

Additional requirements reflecting the needs of the national economy

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Bolt GOST 7798-70

High-strength bolt with hexagonal head GOST 7798-70

No matter how technology and technology develop, bolts have been and remain the main means of creating a detachable connection. From the time of the Industrial Revolution to the present day, they have been widely used in all areas of the economy: in mechanical engineering, in instrumentation, in energy, in transport, in agriculture, in the mining industry, etc.

Bolts perceive shear, tension and bending forces, and therefore are effective for connecting various parts - flanges, plates, beams. This fastener is indispensable in cases where:

• you need to create a detachable connection;
• it is impossible to create a welded joint;
• the material of the parts does not allow threading in them;
• the material of the parts is not able to provide sufficient strength and durability of the thread.

GOST 7798-70 defines the dimensions and main performance characteristics of hex bolts.

The GOST 7798-70 bolt is a rod with a metric thread and a hexagonal head, the material of which is steel grades 10, 20, 10 kp, 20kp, 35, 30XP, 40X. The diameter of the threaded part is in the range from 6 mm (M6) to 48 mm (M48).

Hexagon bolt GOST 7798-70 must comply with normal accuracy (class B) and strength classes 4.8; 5.8; 6.8; 8.8; 10.9. The first digit of the strength class is 1/100 of the tensile strength (in MPa). The second figure is the ratio of tensile strength to yield strength, multiplied by 10. Thus, the strength class makes it possible to judge the most significant performance characteristics of this type of fastener.

Bolts with a tensile strength of 800 MPa and above are called high-strength. They perceive high static and dynamic stresses. The high-strength bolt is able to work equally reliably in aggressive environments, at high-temperature loads and at low temperatures. The material for this fastener is steel grades 30XP, 40X. It is used in metallurgy, in the chemical, pharmaceutical industries, for work in the Far North and in all cases where it is necessary to ensure high bond strength.

Bolt GOST 7798-70 can have threads with fine or coarse pitch. Coarse pitch threads are the most common, since their accuracy is less affected by manufacturing errors.

At the same time, the fine pitch thread provides higher strength of the threaded part of the shank without compromising the strength of the thread. And, besides, fine-pitch threads have a higher reliability of self-braking compared to coarse-pitch threads. All together works to increase the reliability of the connection.

Hex head bolts are produced at the AVALDA plant of accuracy class B according to GOST 7798-70 and GOST 7805-70 with popular sizes M6, M8, M10, M12, M14, M16, M18, M20, M24, M30, M36, M42 price below the market due to its own raw materials: circles and wire. Bolts are used for fastening various structures and products made of different materials: wood, plastic, metal, plywood, concrete; from chairs to bridge assembly and aerospace.

Thread - in accordance with GOST 24705. Thread run-out and undercut - in accordance with GOST 27148. Bolt ends - in accordance with GOST 12414.

Thread tolerance field: 6g

Strength class:

• 4.8, 5.8 from steel 10, 20;
• 8.8, 10.9 from steel 35, 20G2R, 30G1R

Coating types:

Galvanic coating up to 20 microns;
- thermal diffusion galvanizing coating thickness up to 30 microns;
- black oxide film with additional oiling;
- uncoated with oiling.

Package:

In wooden boxes of 50 kg. The boxes are stacked on pallets. Or polypropylene bags for piece orders and according to drawings!

To buy hex bolts, you need to place an order correctly:

Bolt M14-6g 30.58 (S21) GOST 7798-70 is decoded as follows: bolt version 1 with thread diameter = 14 mm, with turnkey size = 21 mm, length = 30 mm, with a large thread pitch with a tolerance field of 6g, class strength 5.8, uncoated

What is the difference between GOST 7798-70 bolts and GOST 7805-70 bolts?

The difference between the bolts lies in the diameter of the circumscribed circle, the GOST 7805-70 bolt is 0.2 mm larger than the GOST 7798-70 bolt, as well as in the dimensions produced

Specifications and Design of Hex Head Bolts

Weight of 1000 pieces of bolts GOST 7798-70 and GOST 7805-70, kg.

Hex head bolts buy at a wholesale price at the AVALDA metallurgical plant by phone or order via e-mail, Online - order. Delivery to the object. Production according to the drawings and requirements of the customer within 10 working days. Certificate. Quality passport.

Retail prices for bolts GOST 7798-70:

Bolts GOST 7798-70

A bolt is a fastening element of any connection, in this case, designed to connect flanged pipe fittings to a pipeline or to create a detachable flange connection for various purposes in a pipeline section.
The GOST 7798-70 bolt is a steel rod of a certain length, having a hexagonal head for a wrench at one end, and an external thread at the other end.

Requirements for fasteners used in flange connections, including requirements for GOST 7798-70 bolts, are given in GOST 20700-75. GOST 7798-70 bolts are manufactured from various steel grades. Depending on the purpose of fasteners and specific conditions of use, these can be carbon, stainless, cold-resistant, heat-resistant and other steels.
Bolt sizes GOST 7798-70:

Note: it is not recommended to use bolts with length dimensions enclosed in brackets. In order to correctly select fasteners, in particular GOST 7798-70 bolts, for connecting flanges, it is necessary to know exactly a number of parameters of the completed pipeline system. These include:

• working pressure in the pipeline;
• working environment temperature;
• working environment (aggressive, non-aggressive, liquid, gaseous, etc.);
• indicators of the external environment (ambient temperature, humidity, pollution with harmful substances, etc.);
• steel grade of installed flanges.

For reliable and tight fastening of a flange connection with bolts GOST 7798-70, nuts, washers and sealing material (paronite or rubber gaskets) are used.

An example of a symbol for a bolt of version 1 with a thread diameter d = 12 mm, with a turnkey size S = 18 mm, a length l = 60 mm, with a large thread pitch with a tolerance field of 6g, strength class 5.8, uncoated:

Bolt M12 - 6g x60.58 (S 18) GOST 7798-70

Bolts GOST 7798-70 are produced in various designs. Bolt head options are set by the manufacturer.

For bolts of execution 1, the diameter of the smooth part is equal to the nominal diameter of the thread. For bolts of version 2, the diameter of the smooth part is approximately equal to the average diameter of the thread. Bolts of version 1 are made without cotter holes, version 2 - with a cotter hole in the shaft, version 3 - with two through holes in the head, version 4 - version of the bolt head with a hole on the end of the bolt head. The through holes in the head of the bolts are designed for cottering with wire to prevent self-unscrewing.

Bolts GOST 7798-70 have a metric thread according to GOST 24705-2004 of a fixed length. The thread tolerance field indicates the accuracy of its execution. The larger the value of the tolerance field, the greater the deviation of the thread parameters from the nominal ones. For flange fasteners, including GOST 7798-70, the tolerance field for external thread is considered sufficient - 6g. The thread pitch is the distance between the tops of the threads. The thread pitch can be large or small. Coarse bolt thread pitch is used more often.

For carbon steel fasteners, the strength class is indicated by two numbers separated by a dot. For example: 4.6, 8.8, 10.9 etc.

The first digit indicates 1/100 of the nominal tensile strength, measured in MPa. In the case of 8.8, the first 8 means: 8 x 100 = 800 MPa (8000 kgf / cm²).

The second digit is the ratio of the yield strength to the tensile strength multiplied by 10. In our example, the second 8 means: Yield strength / 8 x 10. Hence the yield strength \u003d 8 x 8 x 10 \u003d 640 MPa (6400 kgf / cm²).

The yield strength is the maximum working load of the bolt. When calculating a bolted connection for a given load, a coefficient of 0.5-0.6 from the yield strength is used, i.e. with a yield strength of 6.4 tons, the calculated load will be: 6.4x0.5 = 3.2 tons.

Bolt dimensions (diameter and length) D(mm)xL(mm) according to GOST 7798-70
and GOST 10602-94 for flange connections for various pressures (Ru)