GOST R 52643-2006 high-strength bolts and nuts and washers for metal structures. general specifications (with amendment n 1)

M20 stainless bolts price per piece.

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6.1 Test program

The tests are carried out depending on the grade of the material and the length of the bolt or studs, as indicated
Table 5.

Table 5 - Test program

Peculiarities

The term "stainless steel bolts" itself refers to a wide range of stainless steel metal products. Their appearance is simple - it is a cylindrical rod with a special thread. One edge of the structure is equipped with a special head. The main task of the bolt is to firmly fix the parts to be connected. Along with fixation in the internal volume of the part, fixation using a nut can also be carried out.

The detachable nature of bolted connections can be both an advantage and a disadvantage, depending on the specific situation. Various grades of steel are used for the production of bolts. Proven alloying components are added to it, increasing corrosion resistance and technical and operational parameters.

GOST 7798-70 previously applied to stainless bolts. Now it has been replaced by GOST R ISO 3506-1-2009. According to the current standard, tests for compliance with the declared characteristics are carried out at temperatures not lower than -15 and not higher than +25 degrees. A significant difference in mechanical parameters is allowed when the temperature goes beyond these limits. Corrosion resistance, oxidation rate and mechanical parameters under non-standard conditions must be agreed by the manufacturers and recipients.

The test procedures are carried out on special devices with automatically centering clamps. This prevents the effects of bending loads. The error when measuring dimensions cannot exceed 0.05 mm. Yield strengths are set using pre-assembled screws and bolts. The procedure itself involves determining the degree of elongation of the bolt under axial pulling load.

How to properly tighten and unscrew the bolt

Most often, when tightening bolted connections on various structures in the household, ordinary wrenches are used - socket, open-end and ring wrenches. However, in this case, it is difficult to accurately determine the tightening torque, therefore, in industrial production and repair shops, experienced locksmiths use special torque wrenches or pneumatic wrenches, the main advantage of which is the ability to set the required tightening level, depending on the type of mechanism.

To unscrew the bolt, use the same wrenches, but in older designs, most often the bolts "stick" strongly to the nut due to corrosion. For safe unscrewing, several simple methods are used:

• use of penetrating grease WD-40 aerosol type;
• slight tapping on the rusty bolt with a hammer to break the rust in the profile of the threaded connection;
• turning the nut slightly in the direction of tightening (only a few degrees).

Bolt marking according to their strength class

The bolt marking system, the meaning of which can be viewed in special tables to determine which type of fastener is right for you, was developed by the International Organization for Standardization (ISO). All standards developed during the Soviet era, as well as modern Russian regulatory documents, are based on the principles of this system.

Bolts and screws with a diameter of more than 6 mm are subject to mandatory marking. Fasteners with a smaller diameter are marked at the request of the manufacturer.

Marking is not applied to screws with a Phillips or straight slot, and products with a hex slot and any head shape are required to be marked.

Unstamped bolts and screws that are made by turning or cutting are also not subject to mandatory marking. Marking on such products is applied only when required by the customer of such products.

Standard location of bolt markings

The place where the marking of a bolt or screw is applied is the end or side part of their head. In the event that the side of the fastener is selected for this purpose, the marking should be applied in recessed characters. Convex markings in height must not exceed:

• 0.1 mm - for bolts and screws, the thread diameter of which does not exceed 8 mm;
• 0.2 mm - for fasteners, the thread diameter of which is in the range of 8–12 mm;
• 0.3 mm - for bolts and screws with a thread diameter greater than 12 mm.

The geometry of various types of threaded fasteners is regulated by separate GOSTs. As an example, consider products manufactured in accordance with GOST 7798-70. Such hex head bolts, belonging to the category of normal precision products, are actively used in various fields of activity.

3.2 Marking

Fasteners that meet all of the requirements of this standard are marked
and (or) denote in accordance with Fig.

3.2.1 Boltsandscrews

All bolts and hex head screws and hex head screws, nominal thread diameterd≥5 mm must be clearly marked in accordance with Figures 1 and 2. Marking is mandatory and must include all brands of steel and strength class, as well as commercially available
manufacturer's mark. Other types of bolts and screws should be marked as similar where possible, and
only the header. Additional marking is allowed if it does not cause confusion.

3.2.2 Hairpins

Studs nominal thread diameterd≥6 mm must be marked in accordance with Figures 1 and 2. Marking is done on a smooth part of the pin, and must include the trademark of the manufacturer, the grade of steel and the strength class. If marking on the smooth part is not possible, then marking on the steel mark only with the tip end of the stud is allowed (see Figure 2).

1) Manufacturer's mark.

2) Steel grade.

3) Strength class.

Hexagon head bolt and screw markings

Allen head screw marking (marking options)

Stud marking

Note-Marking of left-hand thread-according to ISO 898-1

Drawing 2 —Markingbolts, screwsandstuds

3.2.3 Package

All packages of any size must be marked with the designation of the product and
trademark of the manufacturer.

3.1 Symbols

Designation system of stainless steel grades and strength classes of bolts, screws and pins
shown in Figure 1. Material designation consists of two parts, separated by a hyphen. The first part denotes the steel grade, the second part - the strength class.

The steel designation (first part) consists of the letters

A-austenitic steel;

C-martensitic steel;

F-ferritic steel, which denotes the grade of steel, and the number, which denotes the range of chemical composition limits for this grade of steel.

The designation of the strength class (second part) consists of two numbers, which denote 0.1 of the minimum determination of the tensile strength.

Examples ofdesignations

1 —austeniticstainlessbecome, cold-deformed, withlimitstrengthonbreaknotless 700 Hmm2 (700 MPa) —A2-70.

2 —martensiticbecome, hardenedandreleased, withlimitstrengthonbreaknotless
700 Hmm2 (700 MPa) —WITH4-70.

1) The steel grades classified in Figure 1 are described in Appendix B and their chemical composition in Table 2.

2) Stainless steels and carbon less than 0.03% can be additionally marked with the letter L.

Example—A4L-80

Drawing 1 —Systemdesignationsstampsstainlessbecomeandclassesstrengthbolts,
screwsandstuds

The importance of choosing the right fastener

Bolts produced by modern industry can differ significantly in their strength classes, which depends mainly on what was used for their manufacture. That is why the choice of bolts corresponding to a particular class should be based on the tasks for which they are planned to be used.

For example, bolts of a lower strength class are suitable for connecting elements of a light, unloaded structure, and high-strength products are required for fastening critical structures operating under significant loads. The most notable of these structures are tower and gantry cranes, respectively, the bolts with the highest strength, began to be called "crane". The characteristics of such fasteners used to connect the elements of the most critical structures are regulated by the requirements of GOST 7817-70. Such bolts are made from high-strength grades of steel, which is also stipulated in the regulatory document.

Fasteners, as you know, are of several types: bolts, nuts, screws, studs. Each of these products has its own purpose. For their manufacture, steels of different strength classes are used. Accordingly, the marking of bolts and other types of fasteners will also differ.

Types of threaded fasteners

To make a threaded connection, at least two parts are needed, one of which has an external thread, and the other has an internal thread. There are several types of construction threads.

Bolt

Through holes are drilled in the parts to be connected, after which a bolt is inserted into the inside, which is tightened on the other side with a nut.

Screw

In this type of connection, the part itself plays the role of a nut, in which a hole is pre-drilled, then a thread is applied, after which another part is fastened with a bolt or screw. If you use self-tapping screws, then it is not necessary to drill a preliminary hole, since the part automatically makes a thread when it is screwed in.

With studs

One end of such a stud is screwed into the knot piece, and a suitable nut is screwed onto the other in a special way.

Threaded hairpin

Features of the connection using a thread

1. Reliability through the use of special metric threads and profile versatility.Numerous studies confirm that with a properly selected bolt strength class, as well as the tightening torque, such a connection can withstand heavy loads, and is also reliably protected from self-loosening.
2. Withstand transverse and axial loads. Made from special grades of steel, the bolts resist loads well in any direction.
3. Simple assembly and disassembly of structures. Despite the fact that after a while it is not easy to unscrew the threaded connection (due to metal corrosion), it is quite possible to do this with the help of special solvents.
4. Low cost of work, which is significantly lower than the cost of welding. Many structures are erected today using bolts because it takes less time and effort.

It should be noted that a small disadvantage of a threaded connection can be considered a strong stress concentration at the root of the thread itself. For this reason, the bolt marking must be selected correctly, in exact accordance with the load that the part is experiencing. This will reduce the risk of both self-loosening when loose, and nut bursting / shearing due to extreme stress.

Countersunk head plow bolt

Species overview

Stainless wheel bolts are widely used. As their name implies, the main area of ​​application is for fixing discs in car wheels. The difference between specific models can be expressed:

• in the size of the head;
• in the dimensions of the thread;
• in the features of the clamping surface.

It is the last aspect - the pressure surface - that is most important. The ability to firmly press the disc against the hub or the brake part depends on it, blocking the displacement. Most often, tapered elements with an angle of 60 degrees in front of the head are used. Such designs can be fitted with a 0.13 cm headrest, although this is not required.

Such designs are suitable for mounting discs from a wide variety of cars. However, in this case, the dimensions of the hubs and discs should be limited to the very same 0.24 cm. To press the wheel stably, all surfaces are lubricated with a graphite-based compound. It is recommended to follow the manufacturer's instructions. For reliability, it is worth using bolts with "secret" heads.

Attention should be paid to anchor fasteners. Such products are mainly used in industrial and civil construction, in interior design.

With the help of an anchor bolt, you can fix decorative products and household appliances in situations where ordinary nails, screws or screws do not help. They fit perfectly even into hard concrete. Also, this fastener is suitable for work on a brick, foam block, aerated block and a wall made of natural stone.

The necessary fixation is due to:

• friction force;
• the gluing effect of adhesives;
• the interaction of the spacer block with the passage walls.

The vast majority of anchors are of the wedge or spacer type. Such solutions help to increase the external section of the working parts. At the same time, the intensity of friction increases. The special coating blocks the corrosive effect and prolongs the service life. The size of a specific product is determined in the marking.

Anchor bolt is considered a universal type of fastener. However, due to its rather high cost, it is impractical to use such structures in houses with wooden walls. With proper use, the following are guaranteed:

• increased resistance to stress;
• clear compliance with the task (since the range is very wide);
• the ability to increase the strength of an already assembled structure;
• ease of installation;
• long service life;
• excellent vibration resistance.

However, the disadvantages of the anchor bolt can be considered not only its high cost, but also the need for advance drilling, and the need to choose fasteners in accordance with the material being processed.

The anchor bolt can be fastened both mechanically and with an adhesive mixture. The second option is suitable for working in a fragile wall, which is made of aerated concrete.The wedge design, or a steel stud with the addition of a collet sleeve, implies an increase in the diameter during the twisting of the rod and its wedging inside the cavity. After inserting such an element into the hole, the nut will need to be tightened with an open-end wrench.

When the stud is screwed in, the cone bushing will touch the collet. At the same time, he himself will unclench and undergo wedging. This solution guarantees increased resistance to stress. But miracles do not happen - according to the laws of mechanics, stress is simply distributed over the entire contact area.

In contrast, a sleeve anchor with nut is ideal for this task. Collet bolt with spacer - its further modernization. The bearing capacity is the same as that of the wedge product. The design is suitable for use in hollow brick and lightweight concrete. The only downside is the high price.

The hexagon head bolt can be made to fit a wide variety of wrench sizes. Subtype - cap bolts with a recessed hexagon. Only the special Torx tool helps to work with them. Such fasteners are in demand in the automotive industry, but they are rarely used unnecessarily.

The end of the survey is appropriate on the hinged bolts. In addition to the main GOST, they must also comply with DIN 444. Such fasteners are suitable for cases when it is necessary to periodically dismantle (disassemble) the structure. Or for situations in which sticking of the bolt is critical.

Dimensions (edit)

The bolt size is determined by the nominal cross-section. So, for M6, the length can vary from 12 to 50 mm; M6x40 is often used. M5 fasteners are usually performed in accordance with GOST 7805-70. In this case, the head height can reach 0.35 cm. The thread is made with a pitch of 0.8 mm (they are not made smaller).

The 140mm size can only have a 24mm threaded bolt. Its length fluctuates from 5 to 20 cm... Bolts are also quite widely demanded:

• M8 (head size 0.53 cm, rifling pitch from 1 to 1.25 mm);
• M10 (0.64 cm; 1.25 / 1.5 mm, respectively);
• M12 (always with a high DIN accuracy category);
• M16 (fine cuts 1.5 mm, coarse - 2 mm, length - from 3 to 12 cm).