Checking the tightening of bolted connections with a torque wrench. Thermal imaging control of contact connections. Basic technological operations

4.11. When assembling the joints, the holes in the structural parts must be aligned and the parts must be fixed from displacement with assembly plugs (at least two), and the packages must be tightly tightened with bolts. In connections with two holes, the assembly plug is installed in one of them.

4.12. In the assembled package, the bolts of the diameter specified in the project must go through 100% of the holes. It is allowed to clean 20% of the holes with a drill, the diameter of which equal to the diameter holes indicated in the drawings. At the same time, in connections with the work of bolts for shear and connected elements for crushing, blackness (mismatch of holes in adjacent parts of the assembled package) is allowed up to 1 mm - in 50% of the holes, up to 1.5 mm - in 10% of the holes.

In case of non-compliance with this requirement, with the permission of the organization - the developer of the project, the holes should be drilled to the nearest larger diameter with the installation of a bolt of the appropriate diameter.

In joints with bolts working in tension, as well as in joints where bolts are installed structurally, the blackness should not exceed the difference between the diameters of the hole and the bolt.

4.13. It is forbidden to use bolts and nuts that do not have the brand of the manufacturer and the marking indicating the strength class.

4.14. No more than two round washers (GOST 11371-78) should be installed under the nuts of the bolts.

It is allowed to install one of the same washers under the bolt head.

In necessary cases, oblique washers (GOST 10906-78) should be installed.

The thread of the bolts should not go into the depth of the hole by more than half the thickness of the outermost element of the package from the side of the nut.

4.15. Solutions to prevent self-unscrewing of nuts - setting a spring washer (GOST 6402-70) or a lock nut - must be indicated in the working drawings.

The use of spring washers is not allowed with oval holes, with a difference in the diameters of the hole and the bolt of more than 3 mm, as well as when installed together with a round washer (GOST 11371-78).

It is forbidden to lock the nuts by driving the bolt threads or by welding them to the bolt shank.

4.16. Nuts and locknuts should be tightened from the middle of the connection to its edges.

4.17. The heads and nuts of bolts, including foundation bolts, should, after tightening, be in close contact (without gaps) with the planes of washers or structural elements, and the bolt shaft protrude from the nut by at least 3 mm.

4.18. The tightness of the screed of the assembled package should be checked with a probe 0.3 mm thick, which, within the zone limited by the washer, should not pass between assembled parts to a depth of more than 20 mm.

4.19. The tightening quality of permanent bolts should be checked by tapping them with a 0.4 kg hammer, while the bolts should not move.

Field connections on high-strength bolts with controlled tension1

4.20. To perform connections on bolts with controlled tension, workers who have undergone special training, confirmed by the appropriate certificate, may be admitted.

4.21. In shear-resistant joints, the contacting surfaces of the parts must be processed in the manner provided for in the project.

From surfaces to be treated, as well as not to be treated with steel brushes, it is necessary to first remove oil contamination.

The condition of the surfaces after processing and before assembly should be monitored and recorded in a log (see mandatory Appendix 5).

Before assembling the joints, the treated surfaces must be protected from dirt, oil, paint and ice formation. If this requirement is not observed or the assembly of the joint begins after more than 3 days after the preparation of the surfaces, their processing should be repeated.

4.22. The difference in surfaces (warping) of the joined parts over 0.5 and up to 3 mm must be eliminated by machining by forming a smooth bevel with a slope not steeper than 1:10.

With a difference of more than 3 mm, it is necessary to install gaskets of the required thickness, processed in the same way as the connection parts. The use of gaskets is subject to agreement with the organization - the developer of the project.

4.23. The holes in the parts during assembly must be aligned and fixed from displacement with plugs. The number of plugs is determined by calculating the action of mounting loads, but they must be at least 10% with the number of holes 20 or more and at least two - with a smaller number of holes.

In the assembled package, fixed with plugs, blackness (mismatch of holes) is allowed, which does not prevent the bolts from being set freely without skew. A gauge with a diameter 0.5 mm larger than the nominal diameter of the bolt must pass through 100% of the holes in each connection.

It is allowed to clean the holes of tightly tightened packages with a drill, the diameter of which is equal to the nominal diameter of the hole, provided that the blackness does not exceed the difference between the nominal diameters of the hole and the bolt.

The use of water, emulsions and oils when cleaning holes is prohibited.

4.24. It is forbidden to use bolts that do not have on the head the factory marking of temporary resistance, the brand of the manufacturer, the symbol of the heat number, and on the bolts climatic design HL (according to GOST 15150-69) - also the letters "HL".

4.25. Bolts, nuts and washers must be prepared before installation.

4.26. The tension of the bolts specified by the project should be ensured by tightening the nut or rotating the bolt head until the calculated tightening torque, or by turning the nut through a certain angle, or in another way that ensures that the specified tension force is obtained.

The order of tension should exclude the formation of leaks in the tightened packages.

4.27. Torque wrenches for tensioning and controlling the tension of high-strength bolts must be calibrated at least once per shift in the absence of mechanical damage, as well as after each replacement of the control device or repair of the key.

4.28. Estimated torque M required to tension the bolt should be determined by the formula

M = KRd, Hm (kgf×m), (1)

where To- the average value of the tightening factor, set for each batch of bolts in the manufacturer's certificate or determined at the installation site using control devices;

R- design bolt tension specified in the working drawings, N (kgf);

d - nominal diameter bolt, m.

4.29. The tension of the bolts according to the angle of rotation of the nut should be done in the following order:

manually tighten all the bolts in the connection to failure with a mounting key with a handle length of 0.3 m;

turn the bolt nuts by 180 ± 30°.

This method is applicable for bolts with a diameter of 24 mm with a package thickness of up to 140 mm and the number of parts in a package of up to 7.

4.30. Under the head of a high-strength bolt and a high-strength nut, one washer must be installed in accordance with GOST 22355-77. If the difference between the diameters of the hole and the bolt is not more than 4 mm, it is allowed to install one washer only under the element (nut or bolt head), the rotation of which ensures the tension of the bolt.

4.31. Nuts tightened to the rated torque or turned through a certain angle should not be additionally secured with anything.

4.32. After tensioning all the bolts in the connection, the senior assembly worker (foreman) is obliged to designated place put a stamp (a number or sign assigned to it).

4.33. Bolt tension should be controlled:

with the number of bolts in the connection up to 4 - all bolts, from 5 to 9 - at least three bolts, 10 or more - 10% of the bolts, but not less than three in each connection.

The actual twisting moment must not be less than the calculated one, determined by formula (1), and not exceed it by more than 20%. Deviation of the angle of rotation of the nut is allowed within  30°.

If at least one bolt is found that does not meet these requirements, a double number of bolts is subject to control. If, upon re-checking, one bolt with a lower torque value or with a smaller nut rotation angle is found, all bolts must be checked to bring the torque or nut rotation angle of each to the required value.

A probe 0.3 mm thick should not enter the gaps between the connection parts.

4.34. After checking the tension and accepting the connection, all external surfaces of the joints, including bolt heads, nuts and parts of the bolt threads protruding from them, must be cleaned, primed, painted, and the gaps in the places of thickness difference and gaps in the joints are filled.

4.35. All tensioning and tension control work should be recorded in a log of connections made on bolts with controlled tension.

4.36. Bolts in flanged connections must be tightened to the forces specified in the working drawings by rotating the nut until the calculated tightening torque. 100% of the bolts are subject to tension control.

The actual twisting moment must not be less than the calculated one, determined by formula (1), and not exceed it by more than 10%.

The gap between the contacting planes of the flanges at the location of the bolts is not allowed. A probe 0.1 mm thick must not penetrate into an area with a radius of 40 mm from the bolt axis.

As you know, depending on the design, purpose, method of connecting materials, scope and other factors, contact connections are distinguished: bolted, welded, soldered and made by compression (pressed and twisted).
Contact connections include spacers for wires.

During the operation of contact joints made by welding, the causes of defects in them may be: deviations from the specified parameters, undercuts, bubbles, cavities, lack of penetration, sagging, cracks, slag and gas inclusions(shells), unsealed craters, burnt-out wires, misalignment of connected conductors, incorrect choice of lugs, lack of protective coatings on connections, etc.
Thermal welding technology does not provide reliable operation of welded wire connectors of large cross sections (240 mm2 or more). This is due to the fact that due to insufficient heating in the process of welding the connected wires and uneven convergence of their ends, the outer layers of the wires burn out, lack of penetration, shrinkage cavities and slags appear at the welding site. As a result, the mechanical strength of the welded joint is reduced. Under mechanical loads less than calculated, a wire breakage (burnout) occurs in the anchor support loop, which leads to emergency shutdowns of overhead lines with a short period of their operation. If individual wire conductors are broken in a welded joint, this leads to an increase in the contact resistance of the contact and an increase in its temperature.
The rate of defect development in this case will significantly depend on a number of factors: the value of the load current, wire tension, wind and vibration effects, etc.
Based on the experiments carried out, it was found that:

a decrease in the active cross section of the wire by 20 - 25% due to the breakage of individual conductors may not be detected during IR control from a helicopter, which is due to the low emissivity of the wire, the distance of the thermal imager from the route by 50 - 80 m, the influence of wind, solar radiation and other factors;
when rejecting defective contact joints made by welding using a thermal imager or pyrometer, it must be borne in mind that the rate of development of a defect in these joints is much higher than that of bolted contact joints with pressing;
defects in contact joints made by welding, detected by a thermal imager when examining overhead lines from a helicopter, must be classified as dangerous if their excess temperature is 5 ° C;
steel bushings not removed from welded section wires may give a false impression of possible heating due to the high emissivity of the annealed surface.

In contact connections made by crimping, there are incorrect selection of lugs or sleeves, incomplete insertion of the core into the lug, insufficient degree of crimping, displacement of the steel core in the wire connector, etc. As you know, one of the ways to control molded connectors is to measure their DC resistance.
The criterion for an ideal contact connection is the equality of its resistance to the resistance of an equivalent section of the whole wire. A crimped connector is considered serviceable if its resistance is not more than 1.2 times the equivalent section of the whole wire. When the connector is pressed, its resistance drops sharply, but with an increase in pressure, it stabilizes and changes slightly.
The resistance of the connector is very sensitive to the state of the contact surface of the pressed wires. The appearance of aluminum oxides on the contact surfaces leads to a sharp increase in the contact resistance of the connector and increased heat generation.
Insignificant changes in the contact resistance of the contact connection during their pressing, as well as the associated low heat generation in the contact connection, indicate a lack of efficiency in detecting defects in them immediately after installation using infrared technology devices. During the operation of pressed contact joints, the presence of defects in them will contribute to a more intense formation of oxide films and increase the transition resistance, which can lead to the appearance of local heating. Therefore, we can assume that IR testing of new crimped contact connections does not allow detecting crimping defects and should be carried out for connectors that have worked for a certain period (1 year or more).
The main characteristics of crimped connectors are the degree of crimping and mechanical strength. With the increase mechanical strength connector, its contact resistance decreases. The maximum mechanical strength of the connector corresponds to the minimum electrical contact resistance.

Contact connections made with bolts most often have defects due to the absence of washers at the junction of a copper conductor with a flat copper or aluminum alloy terminal, the absence of belleville springs, direct connection of the aluminum lug to the copper terminals of equipment in rooms with an aggressive or humid environment , as a result of insufficient tightening of bolts, etc.
Bolted contact connections of aluminum tires for high currents (3000 A and above) are not sufficiently stable in operation. If contact connections for currents up to 1500 A require tightening of the bolts once every 1 - 2 years, then similar connections for currents of 3000 A and above require an annual overhaul with indispensable cleaning of the contact surfaces. The need for such an operation is due to the fact that in high-ampere busbars (busbars of power plants, etc.) made of aluminum, the process of formation of oxide films on the surface of contact joints proceeds more intensively.
The process of formation of oxide films on the surface of bolted contact joints is facilitated by various temperature coefficients of linear expansion of steel bolts and aluminum busbars. Therefore, when a short-circuit current passes through the busbar, when it is operated with a variable current load, the contact surface of the aluminum bus is deformed (compacted) as a result of vibration effects. In this case, the force that tightens the two contact surfaces of the busbar weakens, the lubricant layer between them evaporates, etc.
Due to the formation of oxide films, the contact area, i.e. the number and size of the pads (the number of points) through which the current passes decrease and, at the same time, the current density increases, which can reach thousands of amperes per square centimeter, as a result of which the heating of these points increases greatly.
The temperature of the last point reaches the melting point of the contact material, and a drop of liquid metal is formed between the contact surfaces. The temperature of the drop, rising, reaches a boil, the space around the contact connection is ionized, and there is a danger of a multi-phase short circuit in the switchgear. Under the action of magnetic forces, the arc can move along the busbars of the switchgear with all the ensuing consequences.
Operating experience shows that, along with multi-ampere busbars, single-bolt contact connections also have insufficient reliability. The latter, in accordance with GOST 21242-75, are allowed to be used for a rated current of up to 1,000 A, however, they are already damaged at currents of 400 - 630 A. Increasing the reliability of single-bolt contact connections requires the adoption of a number of technical measures to stabilize their electrical resistance.
The process of development of a defect in a bolted contact connection, as a rule, proceeds for a rather long time and depends on a number of factors: load current, operating mode (stable load or variable), exposure to chemical reagents, wind loads, tightening forces of bolts, stabilization of contact pressure, etc.
The contact resistance of a bolted contact connection depends on the duration of the current load. The contact resistance of the contact joints gradually increases up to a certain point, after which there is a sharp deterioration in the contact surface of the contact joint with intense heat release, indicating an emergency state of the contact joint.
Similar results were obtained by specialists from Inframetrics (USA) during thermal tests of bolted contact joints. The increase in the heating temperature during the tests was gradual in nature during the year, and then there was a period of a sharp increase in heat release.

Failures of contact connections made by twisting occur mainly due to installation defects. Incomplete twisting of the wires in oval connectors (less than 4.5 turns) causes the wire to pull out of the connector and break. Uncleaned wires create a high contact resistance, resulting in overheating of the wire in the connector, possibly burning it out. There have been repeated cases of pulling out the lightning protection cable AZhS-70/39, twisted to a smaller number of turns, from the oval connector brand SOAS-95-3 overhead lines 220 kV.

Rice. A photograph of the place where the spacer is fastened with a break in the conductors as a result of vibration effects (a) and a diagram of the flow of load currents in the two-wire phase of the switchgear or overhead lines when the conductors are broken at the place where the spacers are attached (b)

Distance spacers.

The unsatisfactory design of some versions of the spacers, the impact of vibration forces and other factors can lead to chafing of the wire conductors or their break (Fig. 34). In this case, a current will flow through the spacer, the value of which will be determined by the nature and degree of development of the defect.

Analysis of the results of thermal imaging control of contact joints

Welded contact connections.

During thermal imaging control of contact connections, their condition can be assessed in accordance with the “Scope and standards for testing electrical equipment” by the defectiveness coefficient or by the value of excess temperature. Experiments carried out by Yuzhtechenergo revealed insufficient efficiency of the thermal imaging method for detecting a defect in a welded contact joint on early stage development, especially in the control of contact connections of wires of overhead lines from a helicopter. For welded contact joints, it is preferable to assess their condition by the value of excess temperature.

Pressed contact connections.

At one time, the values of defectiveness coefficients were used as criteria for assessing the state of pressed contact joints on outdoor switchgear and overhead lines, i.e. the ratio of the measured resistance or voltage drop across a connector to the resistance of an identical section of a whole wire.
With the advent of devices and CT, the assessment of the state of molded contact joints can be carried out by the value of excess temperature or by the coefficient of defectiveness.
The question arises about the degree of effectiveness of each of these methods for assessing the state of pressed contact joints. To solve this problem, Mosenergo carried out load tests of a section of ASU-400 wire with serviceable and defective connectors.
The defectiveness coefficients for direct current (Kx - 9) and for voltage drop (K2 = 5) were preliminarily determined. The results of load tests (Table 1) showed that for molded connectors, the most preferable method is to evaluate contact connections by the value of excess temperature.

Current value	Heating temperature, "C			Coefficient
load, A		good contact connection	defective contact connection	defects

So, at a current of (0.3 - 0.4) / nom, the excess temperature values are 7-16 ° C, which is quite confidently recorded by the IKT device.
The results of the experiments carried out are in good agreement with the recommendations of the “Scope and Standards for Testing Electrical Equipment”. When evaluating the state of pressed contact joints by the values of defectiveness coefficients, it must be borne in mind that at the initial stage of manufacture (during installation) contact joints have a defectiveness coefficient of 0.8 - 0.9.

The failure of a pressed contact connection develops gradually and largely depends on compliance with the compression technology and the pressure developed in this case. The optimal condition is considered to be the one in which the maximum degree of compression corresponds to minimum value contact resistance of a contact connection.

Bolted contact connections.

Both in domestic and foreign practice, the assessment of the state of a bolted contact connection by the value of excess temperature has become the most widely used.
The process of defect development in a bolted contact joint was studied by Inframetrics (USA) on an operating connection at a load current of 200 A. The experiment showed that the process of defect development in the absence of external climatic, vibrational and other factors and a load that is stable in time can take a very long time .
Based on the test results, the company proposed the following limit values for excess temperature at rated current:
a)< 10 °С - нормальная периодичность тепловизионного контроля;
b) 10 - 20 °С - accelerated thermal imaging control;
c) 20 - 40 °С - thermal imaging control every month;
d) > 40 °С - emergency heating.
The system proposed by the company for assessing the state of bolted contact joints by heating temperature, in principle, does not differ from that regulated by the “Scope and standards for testing electrical equipment”.

Rice. 2. Dependence of the excess temperature of the bolted contact connector on the load current:
1 - with a reduction in the contact area of the contact surfaces by 40%; 2 - the same, 80%

The influence of the heating temperature of bolted contact joints on the degree of defect development was investigated by Yuzhtekhenergo. For this purpose, load tests of bolted contact joints were carried out while simulating a reduction of 40 and 80% of the contact surface area (Fig. 35). The possibility of detecting defects of this kind during thermal imaging control was confirmed and it was shown that defects at an early stage of development can be clearly detected at load currents (0.3 - 0.4) / nom.
Cyclic long-term tests of bolted contact connections show that the stability of their contact transient resistance is largely determined by the design of the fastening fittings (presence of spring washers, etc.). When conducting thermal imaging control, the identification of contact joints with increased heating requires the adoption of certain stabilization measures, for example, decommissioning or temporary load reduction. In the latter case, the current /admissible for a given defective contact connection can be determined from the relation

Controlled nodes
	heating temperature, °С		temperature rise, "C
1. Current-carrying (with the exception of contacts and contact connections) and non-current-carrying metal parts:
uninsulated and not in contact with insulating materials
insulated or in contact with insulating materials of heat resistance classes according to GOST 8865-93:






2. Copper and copper alloy contacts: uncoated (in air/in insulating oil)
with applied silver plates (in air/in insulating oil)
silver or nickel plated (in air/in insulating oil)
with a silver coating with a thickness of at least 24 microns

3. Ceramic-metal tungsten- and molybdenum-containing contacts in insulating oil based on copper/silver
4. Hardware outputs made of copper, aluminum and their alloys, intended for connection with external conductors of electrical circuits:
without cover
tin, silver or nickel plated
5. Bolted contact connections made of copper, aluminum and their alloys:
uncoated (in air/in insulating oil)
tin coated (in air/in insulating oil)
Controlled nodes		Maximum allowable value
		temperature heating, “C		exceeding temperature, "C
silver or nickel plated (in air/in insulating oil)
6. AC fuses for voltage 3 kV and above:
connections made of copper, aluminum and their alloys (uncoated/tin-coated in air):
with detachable contact connection made by springs
with detachable connection (pressed with bolts or screws), including fuse leads
metal parts used as springs:

of phosphor bronze and similar alloys
7. Insulating oil in the upper layer of switching devices
8. Built-in current transformers:

magnetic circuits
9. Bolted connection of current-carrying conclusions of removable inputs (in oil/in air)
10. Connections of on-load tap-changers of power trans
shapers made of copper, its alloys and copper-containing compositions without silver coating when working in air/in oil:
with pressing bolts or other elements that ensure the rigidity of the connection
spring-loaded and self-cleaning during shifting
spring-loaded and not self-cleaning during shifting
11. Conductors power cables in continuous / emergency mode in the presence of insulation:
PVC and polyethylene

Controlled nodes	Maximum allowable value
Controlled nodes	heating temperature, °С	temperature rise, “С
made of vulcanizable polyethylene
rubber
made of high temperature resistant rubber
with impregnated paper insulation with viscous / depleted impregnation and rated voltage, kV:





12. Collectors and slip rings, unprotected and protected with insulation heat resistance classes:


13. Plain/roller bearings

Note. The data given in the table is used if other standards are not established for specific types of equipment.
where /load, ΔTmeas - current and temperature rise of the measured contact connection, respectively; ΔTnorm - the temperature rise of the contact connection, regulated by the "Scope and standards for testing electrical equipment", depending on the type of coating of contact surfaces and the environment in which they are located.
Assessment of the thermal state of electrical equipment and current-carrying parts, depending on the conditions of their operation and design, can be carried out: according to normalized heating temperatures (temperature rises), excess temperature, defectiveness coefficient, dynamics of temperature change over time, with load changes, by comparing measured temperature values within phases and between phases with temperature values in known good areas.
The limit values of the heating temperature for /nom and its excess are given in Table. 16.

For contacts and bolted contact connections, the standards given in Table. 16, should be used at load currents (0.6 - 1.0) / nom after appropriate conversion. The conversion of the excess of the measured temperature value to the normalized one is carried out according to the ratio

where ΔTnom - temperature rise at /nom; ΔTwork - the same, at g
slave-
Thermal imaging control of electrical equipment and current-carrying parts at load currents of 0.3/nom and below does not contribute to the detection of defects at an early stage of their development.
For contacts and bolted contact connections at load currents (0.3 - 0.6) / nom, their condition is assessed by excess temperature. As a standard, the temperature value converted to 0.5 / nom.
The ratio is used for recalculation

where ΔT0.5 is the excess temperature at a load current of 0.5/nom.
When assessing the condition of contacts and bolted contact connections by excess temperature at a load current of 0.5 / nom, the following areas are distinguished according to the degree of failure:

excess temperature 5-10 °C. The initial degree of failure, which should be kept under control and corrective action taken during scheduled repairs;
excess temperature 10 - 30 °C. developed defect. Measures should be taken to eliminate the malfunction at the nearest withdrawal of electrical equipment from work;
excess temperature over 30 °C. emergency defect. Requires immediate elimination.

It is recommended to assess the state of welded and made by crimping contact joints by excess temperature or defectiveness factor.
When assessing the thermal state of current-carrying parts, the following degrees of failure are distinguished, based on the given values of the defectiveness coefficient:
Not more than 1.2 .............................................. ... Initial degree of malfunction, Forward

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BEARING AND Fencing STRUCTURES - BUILDING NORMS AND RULES - SNiP 3-03-01-87 (approved by the Decree of the USSR Gosstroy dated 04-12-87 ... Relevant in 2017

Field connections on high-strength bolts with controlled tension

4.20. To perform connections on bolts with controlled tension, workers who have undergone special training, confirmed by the appropriate certificate, may be admitted.

4.21. In shear-resistant joints, the contacting surfaces of the parts must be processed in the manner provided for in the project.

From surfaces to be treated, as well as not to be treated with steel brushes, it is necessary to first remove oil contamination.

The condition of the surfaces after processing and before assembly should be monitored and recorded in a log (see mandatory Appendix 5).

4.22. The difference in surfaces (warping) of the joined parts over 0.5 and up to 3 mm must be eliminated machining by forming a smooth bevel with a slope not steeper than 1:10.

4.23. The holes in the parts during assembly must be aligned and fixed from displacement with plugs. The number of plugs is determined by calculating the action of mounting loads, but they must be at least 10% with the number of holes 20 or more and at least two - with a smaller number of holes.

The use of water, emulsions and oils when cleaning holes is prohibited.

4.24. It is forbidden to use bolts that do not have a factory marking of temporary resistance on the head, the brand of the manufacturer, the symbol for the heat number, and on the bolts of the climatic modification HL (according to GOST 15150-69) - also the letters "HL".

4.25. Bolts, nuts and washers must be prepared before installation.

4.26. The tension of the bolts specified by the project should be ensured by tightening the nut or rotating the bolt head to the calculated tightening torque, or by turning the nut through a certain angle, or in another way that ensures that the specified tension force is obtained.

The order of tension should exclude the formation of leaks in the tightened packages.

4.27. Torque wrenches for tensioning and checking the tension of high-strength bolts must be calibrated at least once per shift in the absence of mechanical damage, and also after each replacement of the control device or repair of the key.

4.28. The design torque M required to tighten the bolt should be determined from the formula

where K is the average value of the torque coefficient, set for each batch of bolts in the manufacturer's certificate or determined at the installation site using control devices;

P is the design bolt tension specified in the working drawings, N (kgf);

d - nominal diameter of the bolt, m.

4.29. The tension of the bolts according to the angle of rotation of the nut should be done in the following order:

manually tighten all the bolts in the connection to failure with a mounting key with a handle length of 0.3 m;

turn the bolt nuts by 180° ± 30°.

This method is applicable for bolts with a diameter of 24 mm with a package thickness of up to 140 mm and the number of parts in a package of up to 7.

4.30. Under the head of a high-strength bolt and a high-strength nut, one washer must be installed in accordance with GOST 22355-77. If the difference between the diameters of the hole and the bolt is not more than 4 mm, it is allowed to install one washer only under the element (nut or bolt head), the rotation of which ensures the tension of the bolt.

4.31. Nuts tightened to the rated torque or turned through a certain angle should not be additionally secured with anything.

4.32. After tensioning all the bolts in the connection, the senior assembly worker (foreman) is obliged to put a stamp (the number or sign assigned to him) in the designated place.

4.33. Bolt tension should be controlled:

with the number of bolts in the connection up to 4 - all bolts, from 5 to 9 - at least three bolts, 10 or more -10% of the bolts, but not less than three in each connection.

A probe 0.3 mm thick should not enter the gaps between the connection parts.

4.34. After checking the tension and accepting the connection, all external surfaces of the joints, including bolt heads, nuts and parts of the bolt threads protruding from them, must be cleaned, primed, painted, and the gaps in the places of thickness difference and gaps in the joints are filled.

4.35. All tensioning and tension control work should be recorded in a log of connections made on bolts with controlled tension.

4.36. Bolts in flanged connections must be tightened to the forces specified in the working drawings by rotating the nut until the calculated tightening torque. 100% of the bolts are subject to tension control.

The actual twisting moment must not be less than the calculated one, determined by formula (1), and not exceed it by more than 10%.

The gap between the contacting planes of the flanges at the location of the bolts is not allowed. A probe 0.1 mm thick must not penetrate into an area with a radius of 40 mm from the bolt axis.

In accordance with the document “MDS 12-22.2005. Recommendations for the application in the construction industry of the requirements of regulatory legal and other regulatory acts containing state and regulatory requirements labor protection” Appendix 5, all data related to construction and installation work in production should be entered daily into journal of field connections on bolts with controlled tension. This requirement cannot be bypassed and neglected. In the event of any litigation, this journal will have legal weight and be treated as an official document.

Our store brings to your attention just such a magazine for performing mounting connections on bolts with controlled tension.

It is suitable for you to take into account everything you need during construction and installation work.

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Remember that the journal of assembly connections on bolts with controlled tension is a very important and necessary bureaucratic link in the chain of any construction and installation work. Do not put off buying it for later, because it can be useful to you today. Do not start construction work without a Tension Controlled Bolt Field Connection Book, thinking that you will get it later. Our store is open for you 24/7 and is ready to provide you unlimited quantity magazines. We look forward to your purchases and are happy to help with any questions.

Title page:
- name of the organization performing the work
- name of the construction object
- position, surname, initials and signature of the person responsible for the performance of work and keeping a journal
- the organization that developed the project documentation, drawings of KM
- project code
- the organization that developed the project for the production of works
- project code
- an enterprise that developed KMD drawings and manufactured structures
- order code
- customer (organization), position, surname, initials and signature of the head (representative) of technical supervision

Sections 1
List of link (fitters) involved in the installation of bolts.

Counts journal for performing field connections on bolts with controlled tension:

2. Assigned category

3. Assigned number or sign

4-5. Qualification certificate

date of issue

Issued by

6. Note

Main part

Columns to fill in:
1. Date
2. The number of the KMD drawing and the name of the node (joint) in the connection
3-6. Bolt setting
- the number of supplied bolts in the connection
- certificate number for bolts
- method of processing contact surfaces
- estimated torque or angle of rotation of the nut

7-12. Control results
- processing of contact surfaces
- number of tested bolts
- the results of checking the tightening torque or the angle of rotation of the nut
- stamp number, foreman's signature
- signature of the person responsible for setting the bolts
- signature of the client's representative

The document "MDS 12-22.2005. Recommendations for the application in the construction industry of the requirements of regulatory legal and other regulatory acts containing state regulatory requirements for labor protection" states:
1.5. Data on the production of construction and installation works should be entered daily into

INDUSTRY STANDARD

STRUCTURES BUILDING STEEL. MOUNTING

HIGH STRENGTH BOLTS

Typical technological process

OST 36-72-82

By order of the USSR Ministry of Assembly and Special Construction Works dated December 7, 1982, the introduction period was set from July 1, 1983.

APPROVED AND INTRODUCED BY ORDER of the Ministry of Assembly and Special construction works USSR dated December 7, 1982, No. 267

Performers: VNIPI Promstalkonstruktsiya

K.I. Lukyanov, Ph.D., A.F. Knyazhev, Ph.D., G.N. Pavlova

Co-executors: Central Research Institute Projectstalkonstruktsiya

B.G. Pavlov, Ph.D., V.V. Volkov, Ph.D., V.M. Babushkin

B.M. Weinblat, Ph.D.

Introduced for the first time

This International Standard covers a typical process for making shear-resistant field joints on high-strength bolts in structural steel structures.

The standard establishes technical requirements for the materials used, the structural elements to be joined, the tool, as well as the sequence of operations of the technological process, quality control, and the basics of safety.

1. GENERAL PROVISIONS

1.1. High-strength bolts, nuts and washers should be used in accordance with the instructions of the working (KM) or detailing (KMD) drawings of the steel structures of the object being mounted.

1.2. Projects for the production of work (PPR) should contain schemes for the production of work or technological maps, providing for the implementation of connections on high-strength bolts in specific conditions mounted object.

1.3. Preparation, assembly and acceptance of connections on high-strength bolts should be carried out under the guidance of a person (foreman, foreman) appointed by order of the installation organization responsible for making this type of connection at the facility.

1.4. To make connections on high-strength bolts, fitters are allowed at least 18 years old, who have passed a special theoretical and practical training, confirmed by a personal certificate for the right to perform these works, issued by the installation organization.

2. TECHNICAL REQUIREMENTS

2.1.1. High-strength bolts, nuts, washers must be supplied to the object to be mounted in batches provided with certificates in accordance with the requirements of GOST 22353-77, GOST 22354-77, GOST 22355-77, GOST 22356-77.

2.1.2. For sandblasting (shot blasting) treatment of the contact surfaces of the structural elements to be joined, quartz sand should be used in accordance with GOST 8736-77 or cast iron or steel shot in accordance with GOST 11964-81 E.

2.1.3. To form a glue-friction coating on the contact surfaces of the pads, glue based on epoxy-diane resin ED-20 according to GOST 10587-76 and carborundum powder grades KZ and KCh, fractions No. 8, 10, 12 according to GOST 3647-80 should be used.

2.1.4. For flame treatment of surfaces, acetylene according to GOST 5457-75 and oxygen according to GOST 6331-78 should be used. Acetylene and oxygen must be supplied to the place of work in steel cylinders in accordance with GOST 15860-70.

2.2.1. The possibility of free supply of high-strength bolts and tightening of nuts using wrenches and torque wrenches must be ensured constructive solution connections.

2.2.2. Installation of connections is not allowed if there are burrs on the structural elements around and inside the holes, as well as along the edges of the elements.

The contact surfaces of the elements are not subject to priming and painting. The distance between the axis of the bolts of the last row and the primed surface should not be less than 70mm.

2.2.3. It is not allowed to use elements in joints that have dimensional deviations that do not meet the requirements of SNiP III-18-75 “Rules for the production and acceptance of work. Metal constructions". The difference in the planes of the elements connected by overlays should not exceed 0.5 mm inclusive.

2.2.4. In connections from rolled profiles with non-parallel surfaces of the flanges, leveling gaskets must be used.

2.2.5. The nominal diameters and blackness of the holes (mismatch of holes in individual parts of the assembled package) should not exceed the requirements specified in chapter SNiP III-18-75 "Rules for the production and acceptance of work. Metal structures".

2.2.6. Control and calibration torque wrenches must be numbered, calibrated and provided with calibration charts or tables. Pneumatic and electric wrenches must meet passport requirements.

3.1.1. To preparatory operations include: re-preservation and cleaning of high-strength bolts; preparation of structural elements; control and calibration check of the tool.

3.1.2. High-strength bolts, nuts, washers must be cleaned from factory preservation, dirt, rust and covered with a thin layer of grease. Depreservation and cleaning are carried out according to the following technology.

3.1.3. Place high-strength bolts, nuts and washers weighing no more than 30 kg in a crate.

3.1.4. Immerse the lattice container filled with hardware into a tank with boiling water for 8 - 10 minutes (see drawing).

3.1.5. After boiling, wash the hot hardware in a mixture consisting of 85% unleaded gasoline according to GOST 2084-77 and 15% engine oil (autol type) according to GOST 20799-75 by 2-3 times immersion followed by drying.

3.1.6. Place processed bolts, nuts and washers separately in closed boxes with handles with a capacity of not more than 20 kg for transferring them to the workplace.

3.1.7. On the portable container, indicate the standard sizes, the number of bolts, nuts and washers, the processing date, certificate and lot numbers.

3.1.8. Cleaned bolts, nuts and washers should be stored in closed boxes for no more than 10 days, after which it is necessary to re-process in accordance with paragraphs. 3.1.4 and 3.1.5.

3.1.9. Burrs found around and inside holes, as well as along the edges of elements, must be completely removed. Deburring around the holes and along the edges of the elements should be done with pneumatic or electric grinding machines without forming a recess that breaks the contact of the contacting surfaces, and in the case of burrs inside the hole, with a drill, the diameter of which is equal to the diameter of the bolt.

3.1.10. If the difference in the planes of the connected elements is more than 0.5 to 3.0 mm inclusive, on the protruding element, it is necessary to make a bevel with a cleaning pneumatic or electrical machine at a distance of up to 30.0 mm from the edge of the element. If the difference in planes is more than 3.0 mm, leveling pads should be used.

3.1.11. Calibration (calibration check) of control and calibration torque wrenches should be performed once per shift before starting work on special stands or devices in accordance with the recommended Appendix 1. Wrench torque wrenches are calibrated in accordance with the recommended Appendix 2.

1 - heating element; 2 - lattice container for bolts; 3 - reservoir for water;

4 - drain plug

3.2.1. The main technological operations include:

Processing of contact surfaces;

Assembly of connections;

Installation of high-strength bolts;

Tension and tension control of bolts.

3.2.2. The method of processing contact surfaces is selected in accordance with the coefficient of friction indicated in the drawings of KM or KMD, and chapter SNiP II-23-81 " Steel structures. Design standards".

The following methods of processing contact surfaces, performed at the assembly site, have been established: sandblasting (shot blasting); flame; metal brushes; glue-friction.

3.2.3. Sandblasting (shot blasting) treatment of the contact surfaces of the elements to be joined should be carried out by sandblasting or shot blasting machines in accordance with GOST 11046-69 (ST SEV 3110-81).

When sandblasting (shot blasting) processing of contact surfaces, mill scale and rust must be completely removed until a uniform light gray surface is obtained.

3.2.4. Flame treatment of contact surfaces must be carried out with wide-angle gas-flame burners GAO-60 or GAO-2-72 according to GOST 17357-71.

Flame treatment is allowed with a metal thickness of at least 5.0 mm.

The speed of movement of the burner is 1 m/min with a metal thickness of more than 10 mm and 1.5-2 m/min - with a metal thickness of up to 10 mm inclusive.

Products of combustion and scale should be swept away with soft wire and then with hair brushes.

The surface after flame treatment must be free from dirt, paint, oil stains and easily peeling scale. Complete removal mill scale optional.

The equipment of the gas flame treatment station and a brief technical description of the equipment are given in the recommended appendix3.

3.2.5. Processing of contact surfaces with metal brushes should be carried out using pneumatic or electric grinders, the brands of which are indicated in the recommended appendix 4.

Bring the contact surfaces to be cleaned up to metallic luster not allowed.

3.2.6. Adhesive friction coating on the contact surfaces of the pads, as a rule, is applied at the manufacturing plants of metal structures.

The technological process for obtaining adhesive friction coating provides for:

Processing of contact surfaces of pads in sandblasting (shot blasting) machines according to GOST 11046-69 (ST SEV 3110-81);

Application of epoxy-polyamide glue to the treated contact surfaces of the overlays;

Application of carborundum powder over uncured adhesive.

The safety of the adhesive-friction coating must be ensured by packing the slips for the entire period of their loading, transportation, unloading and storage at the construction site.

The shelf life of slips with adhesive friction coating is not limited.

The composition of the adhesive friction coating is given in the recommended appendix 5.

The contact surfaces of the main connected elements before assembly must be treated with metal brushes in accordance with clause 3.2.5.

3.2.7. Metallization processing of the contact surfaces of the connected structural elements (galvanizing, aluminizing), as a rule, is carried out at the manufacturing plants of metal structures.

3.2.8. Treated surfaces must be protected from dirt, oil and ice formation. The shelf life of structures treated by sandblasting (shot blasting), gas-flame methods or metal brushes, before assembly, should not exceed three days, after which the surfaces should be re-treated in accordance with paragraphs. 3.2.3 -3.2.5.

Surfaces treated with sandblasting (shot blasting) reprocessing can be cleaned using a flame method.

3.2.9. Contact surfaces without treatment should be cleaned of dirt and flaking scale with metal brushes; from oil - unleaded gasoline, from ice - chipping.

3.2.10. The assembly of connections on high-strength bolts includes the following operations:

Alignment of holes and fixation in the design position of the connection elements with the help of assembly plugs, the number of which should be 10% of the number of holes, but not less than 2 pieces;

Installation of high-strength bolts in holes free from assembly plugs;

Tight package tie;

Tension of installed high-strength bolts to the force specified in the KM and KMD drawings;

Removing assembly plugs, placing high-strength bolts in the released holes and tensioning them to the design force;

Connection priming.

3.2.11. Under the heads and nuts of high-strength bolts, it is necessary to put only one heat-treated washer in accordance with GOST 22355-77.

The protruding end of the bolt must necessarily have at least one thread above the nut.

3.2.12. If the holes do not match, they should be drilled in elements with machined surfaces without using coolants.

3.2.13. Preliminary and final tension of high-strength bolts must be carried out from the middle of the connection to the edges or from the most rigid part of the connection towards its free edges.

3.2.14. The method of tensioning high-strength bolts must be indicated in the KM or KMD drawings.

3.2.15. In the absence of instructions, the tensioning method is selected by the installer according to the recommended appendix 2.

4.1. After making the field connection on high-strength bolts, the foreman is obliged to mark the connection with a personal brand (a set of numbers) and present the finished connection to the person in charge.

4.2. The responsible person (foreman, foreman), after inspection and verification, must present the finished connection to the representative of the customer. In the absence of comments from the customer, the connection should be considered accepted and the responsible person enters all the necessary information about it in the journal for performing field connections on high-strength bolts (see mandatory Appendix 6).

4.3. After acceptance, the finished joint should be primed and painted. Soil grades and paintwork material are accepted according to the “List of polymeric materials and products approved for use in construction”, approved by the USSR Ministry of Health, the same as for priming and painting metal structures. Primer and paint grades must be indicated in the KM and KMD drawings.

4.4. The quality of the connections on high-strength bolts is checked by the person in charge by step-by-step control. Subject to control:

Quality of processing of contact surfaces;

Compliance of the installed bolts, nuts and washers with the requirements of GOST 22353-77, GOST 22354-77, GOST 22355-77, GOST 22356-77, as well as other requirements specified in the KM and KMD drawings;

The presence of washers under the heads of bolts and nuts;

The presence on the heads of the bolts of the brand of the manufacturer;

The length of the protruding part of the bolt thread above the nut;

The presence of the stigma of the foreman in charge of the assembly of the compound.

4.5. The quality of the processing of the contact surfaces is checked by visual inspection immediately before assembling the joints. The results of the control must be recorded in a log (see mandatory Appendix 6).

4.6. The compliance of the bolt tension with the design one is checked depending on the tension method. The deviation of the actual torque from the torque indicated in the KM and KMD drawings should not exceed 20%.

The angle of rotation of the nut is determined by the position of the marks on the protruding end of the bolt and nut. With a two-stage bolt tension, the deviation of the angle of rotation should be within ± 15 °, with a single-stage - ± 30 °.

Bolts with marks outside the specified limits must be loosened and re-tightened.

4.7. The tension of high-strength bolts is checked with a calibrated torque wrench or a control calibrated wrench.

The tension of the bolts should be controlled by a random check: with the number of bolts in the connection up to 5 inclusive, 100% of the bolts are controlled, with the number of bolts from 6 to 20 - at least 5, with more- at least 25% of the bolts in the connection.

4.8. If at least one bolt is found during the control, the tension of which does not meet the requirements of clause 4.6 of this standard, then 100% of the bolts in the connection are subject to control. In this case, the tension of the bolts must be brought to the required value.

4.9. The density of the package to be tightened is controlled by 0.3 mm probes. The probe should not pass between the planes along the contour of the connected elements.

4.10. The documentation presented upon acceptance of the finished object, in addition to the documentation provided for by chapter SNiP III-18-75 "Rules for the production and acceptance of work. Metal structures", must contain:

Journal of assembly connections on high-strength bolts;

Certificates for bolts, nuts and washers;

Certificates for materials for the formation of adhesive friction coatings.

5. SAFETY REQUIREMENTS

5.1. The organization of a site for pre-assembly of structures with field connections on high-strength bolts should ensure the safety of workers at all stages of the work.

Works on the installation of structures on high-strength bolts must be carried out in accordance with the PPR, containing following solutions for safety:

Organization of workplaces and passages;

The sequence of technological operations;

Methods and devices for safe work installers;

Location and coverage of mounting mechanisms;

Ways of warehousing building materials and structural elements.

5.2. The placement of working equipment and the organization of workplaces must ensure the safety of evacuation of workers in emergency situations, taking into account current building codes.

5.3. All work at height on the implementation of field connections on high-strength bolts should be carried out from scaffolds that provide Free access to connect to the instrument.

Scaffolding and other devices that ensure the safety of work must comply with the requirements of the chapter SNiPIII-4-80 "Rules for the production and acceptance of work. Safety in construction", GOST 12.2.012-75, GOST 24259-80 and GOST 24258-80.

5.4. Electrical safety at the installation site must be ensured in accordance with the requirements of GOST 12.1.013-78.

5.5. When processing contact surfaces with sandblasting (shot blasting) machines, the “Rules for the Design and Safety of Operation of Pressure Vessels” approved by the USSR Gosgortekhnadzor should be followed.

5.6. The place of production of sandblasting (shot blasting) works should be fenced off and appropriate warning signs and inscriptions should be hung around it.

5.7. Materials for sandblasting (shot blasting) surface treatment (sand, shot, metal sand) should be stored in containers with tightly closed lids.

5.8. The operator of the sandblasting (shot-blasting) apparatus and the auxiliary worker are supplied with space suits or helmets with a forced supply of clean air.

5.9. The air supplied to the suit must first be passed through a filter to remove dust, water and oil.

5.10. Between the workplaces of the operator and the auxiliary worker located near the sandblasting (shot blasting) apparatus, sound or light alarms should be provided.

5.11. When processing contact surfaces with metal brushes (manual and mechanical), workers must be provided with goggles in accordance with GOST 12.4.003-80 or masks, gloves and respirators.

5.12. When processing contact surfaces with a gas-flame method, it is necessary to comply with the requirements of chapter SNiP III-4-80 “Rules for the production and acceptance of work. Safety in construction, as well as sanitary regulations when welding and cutting metals approved by the Ministry of Health of the USSR.

5.13. Places of gas-flame work must be freed from combustible materials within a radius of at least 5 m, and from explosive materials and installations (including gas cylinders and gas generators) - within a radius of 10 m.

5.14. It is not allowed to carry out work on flame treatment of the surfaces of structural elements in rainy weather outdoors without a canopy.

5.15. When performing gas-flame treatment of contact surfaces, workers should be provided with closed-type goggles with glass-light filters of grades G-1 or G-2.

Auxiliary workers must be provided with goggles with light filter glasses of grades B-1 or B-2.

5.16. The application of the adhesive friction layer to the surface of the linings, as a rule, must be carried out at the manufacturing plants. At the same time, safety requirements in accordance with GOST 12.3.008-75, GOST 12.3.016-79 and GOST 10587-76, as well as safety regulations when working with synthetic adhesives, must be observed.

5.17. The preparation of glue and the application of adhesive friction coatings must be carried out in separate room equipped with exchange and local ventilation.

5.18. Persons working with epoxy resins must be provided with overalls and gloves.

For guard skin from the effects of epoxy resins, protective pastes and ointments based on lanolin, petroleum jelly or castor oil should be used.

5.19. The room for applying glue-friction coatings must be provided with fire extinguishers - carbon dioxide and foam fire extinguishers.

5.20. Re-preservation of bolts, nuts and washers should be carried out in an open area with a canopy.

5.21. When boiling hardware in water, the bath must be grounded. Workers re-preserving hardware should not have direct contact with baths for boiling and lubrication. The loading process must be mechanized.

5.22. When performing assembly operations, the alignment of holes and checking their coincidence in the mounted structural elements must be carried out using a special tool - conical mandrels, assembly plugs, etc. It is not allowed to check the coincidence of holes with your fingers.

5.23. The operation of mechanisms, small-scale mechanization, including maintenance, must be carried out in accordance with the requirements of chapter SNiP III-4-80 “Rules for the production and acceptance of work. Safety in construction” and manufacturer’s instructions.

5.24. When using manual machines, you should follow the safety rules provided for by GOST 12.1.012-79 (ST SEV 1932-79, ST SEV 2602-80) and GOST 12.2.010-75, as well as the instructions of manufacturers.

5.25. The working regime when working with manual electric and pneumatic machines and wrenches should be established in accordance with the "Recommendations for the development of the Regulations on the working regime of workers in hazardous professions", approved in December 1971 by the All-Union Central Council of Trade Unions, the USSR Ministry of Health, State Committee Council of Ministers of the USSR on Labor and wages, as well as instructions from manufacturers for performing work with specific types of machines.

5.26. Priming and painting of finished joints on high-strength bolts should be carried out at the site for assembling metal structures.

5.27. Only workers, knowing the rules safe handling with the equipment and materials used and familiar with the rules of fire safety.

5.28. Workers involved in the priming and painting of compounds must undergo a medical examination in accordance with the requirements of Order No. 400 of the USSR Ministry of Health of May 30, 1969 "On conducting preliminary and periodic medical examinations of workers upon admission to work."

5.29. Temporary production and auxiliary premises must be provided with ventilation and lighting, as well as equipped with fire extinguishing equipment in accordance with the requirements of GOST 12.4.009-75.

ATTACHMENT 1

An example of calibration of a torque wrench type KTR-3 1

_________________

1 KTR-3 keys are manufactured by assembly organizations according to the drawings of the Central Research Institute of Projectstalconstruction.

Torque wrenches are calibrated on special calibration stands or by hanging a load of a given value from its handle. A torque wrench is hung on a hexagonal mandrel or a tightened high-strength bolt so that its handle is in a horizontal position (see drawing).

At a fixed point at the end of the key, a weight of mass is suspended

where M h - Estimated twisting moment;

Δ M h- a moment equal to the product of the mass of the key and the distance from the center of gravity to the axis of the mandrel or bolt;

l- distance from the center of gravity of the load to the axis of the mandrel or bolt.

With a suspended load, the reading is carried out using a recording device, for example, a dial indicator IC 10 mm according to GOST 577-68. The measurement is carried out 2-3 times until a stable result is obtained. The results of the calibration are recorded in the log of the control calibration of the keys (see mandatory Appendix 7).

1 - welded hexagon or tightened high-strength bolt;

2 - rigid support; 3 - indicator; 4 - calibrated key; 5 - calibrated cargo

APPENDIX 2

M h required for tensioning high-strength bolts is determined by the formula:

M h= kPd,

k- the average value of the tightening factor for each batch of bolts according to the certificate or set using control devices at the installation site;

R- bolt tension force specified in the KM and KMD drawings;

d- the nominal diameter of the bolt.

1.2. To pre-tighten the nuts, use the pneumatic or electric nutrunners specified in recommended Appendix 4 and torque wrenches.

1.3. When tightening the bolt, the head or nut should be kept from turning with a mounting wrench. If turning does not stop as the bolt is tensioned, then the bolt and nut must be replaced.

1.4. The twisting moment should be recorded during the movement of the key in the direction that increases the tension.

Tightening should be done smoothly, without jerks.

1.5. Torque wrenches must be numbered and calibrated. They should be calibrated at the beginning of the shift.

2.1. High-strength bolts must be installed in holes free from assembly plugs and tightened with a wrench adjusted to a torque of 800 N ⋅ m. Each bolt must be tightened until the nut stops rotating. After removing the assembly plugs and replacing them with bolts, the latter must be tightened to a tightening torque of 800 N⋅ m

2.2. To control the angle of rotation of the nuts, it is necessary to mark them and the protruding ends of the bolts with a combined center punch (see drawing) or paint.

Combined center punch

1 - center punch; 2 - nut; 3 - high-strength bolt; 4 - package

2.3. The final tightening is carried out with a wrench adjusted to the torque of 1600 N ⋅ m, while the nut must turn by the angle indicated in the table.

Number of gaps in the package	Package thickness, mm	Rotation angle, degrees

3.1. Nut runners should be calibrated on a special calibration package consisting of three bodies with at least 20 holes.

High-strength bolts are inserted into the holes of the calibration package and tightened with a wrench until the nut stops rotating. A group of bolts (calibration bolts) in an amount of at least 5 pcs. do not tighten.

The calibration bolts must be tightened by hand with an assembly wrench with a handle length of 0.3 m to failure (initial position).

3.2. On the prepared calibration bolts, the wrench is calibrated.

3.3. The compressed air pressure is set so that when the nut is turned through an angle of 180 ± 30 ° from its original position, the wrench will fail.

The air pressure must be checked periodically.

Air pressure control should be carried out according to the GOST 2405-72 pressure gauge installed at the point where the wrench hose is connected to the line.

3.4. When calibrating a wrench (to monitor the angle of rotation of the nut), marks must be applied to its replaceable head.

3.5. The impact wrench is considered calibrated if the angle of rotation of the nut in the process of tightening all the bolts at the moment of failure of the impact wrench is 180 ± 30°.

3.6. The results of the wrench calibration must be recorded in the wrench calibration log (see mandatory appendix 8).

3.7. In the event of a change in compressed air pressure after the repair of the defect in the wrench, it is necessary to perform a control calibration.

APPENDIX 3

equipment identification
Burner GAO-60, GAO-2-72 GOST 17357-71 (1 pc.)	Wide-cut, multi-flame, grip width 100 mm.
Oxygen cylinders (3 pcs.)
Acetylene cylinders (2 pcs.)
	Maximum inlet overpressure - 1962 ⋅ 10 4 Pa; operating overpressure - 78.48⋅ 10 4 Pa; throughput at maximum pressure - 23m 3 /h
	Maximum overpressure at the inlet - 245.25 ⋅ 10 4 Pa; operating overpressure - from 0.981⋅ 10 4 Pa to 14.715 ⋅ 10 4 Pa; bandwidth - 5 m 3 /h
Rubber sleeves for oxygen supply (GOST 9356-75) with inner diameter 9.0, outer - 18 mm	Operating overpressure 147.15 ⋅ 10 4 Pa

APPENDIX 4

Equipment, mechanisms and tools used, connected elements and tension of high-strength bolts

The vibration levels of electric and pneumatic hand grinders and wrenches (Table 1) do not exceed those established in GOST 16519-79 (ST SEV 716-77) and GOST 12.1.012-78.

Table 1

Name	Brand, standard	Purpose
Electric impact wrenches	IE-3115A IE-3119U2 IE-3112A
Pneumatic impact wrenches	GOST 15150-69 IP-3106A IP-3205A GOST 10210-74
wrenches
Electric hand grinders	IE-2004UZ	For cleaning work
Electric Angle Grinders	IE-2102A
Pneumatic hand grinders		For cleaning metal surfaces from rust and scale
Gas burners	GAO-2-72 GOST 17357-71	For processing contact surfaces

The noise levels of electric and pneumatic hand-held grinders and wrenches do not exceed those established in GOST 12.1.003-76. 2 and 3.

table 2

Vibration parameters

brand


IE-3115A
IE-3119U2
IE-3112A
IE-3120A
IE-2009
IE-2004AUZ
IE-2102A

Table 3

Noise characteristics

brand
cars
	Sound power level, dB
IE-3115A
IE-3119U2
IE-3112A
IE-3120A
IP-3106A
IP-3205A

APPENDIX 5

Name		Cooking method
Epoxy-polyamide adhesive
	Hardener I-5M (I-6M) according to VTU OP-2382-65-60 (50 wt. h) Accelerator UP-606-2 according to MRTU 6-09-6101-69 (2 - 3 wt. h)
abrasive material
Solvent	Acetone according to GOST 2768-79

APPENDIX 6

obligatory

Headquarters

_______________________________________

Object name

_______________________________________

Structural manufacturer, order no.

Journal of control over the implementation of field connections on high-strength bolts

the date	KMD drawing number and name of the node, joint in the connection	Number of supplied bolts in the connection	Bolt Certificate Numbers	Method of processing contact surfaces	Standard tightening torque or angle of rotation of the nut	Control results
the date		Number of supplied bolts in the connection	Bolt Certificate Numbers	Method of processing contact surfaces	Standard tightening torque or angle of rotation of the nut	Contact surface treatment	Number of tested bolts	Torque Test Results	Hallmark number, foreman's signature	Brand number, signature of the responsible person	Signature of the customer's representative

Ch. installation organization engineer _______________________________________

Place of printing

assembly

organizations

APPENDIX 7

obligatory

_______________________________________

Headquarters

_______________________________________

Object name

Journal 1 control calibration of wrenches for tensioning and tension control of high-strength bolts

______________

1 The log is drawn up for all the keys used when making field connections at each object.

During the control calibration, the log must be kept by the responsible person performing the work.

The responsible person fills in the log after each control calibration of the keys. The log is kept until the delivery of the object.

the date	Change	Key		Torque	Indications on the key device	Signature of the responsible person who carried out the calibration
		type of	room

Ch. installation engineer _

Place of printing

installation organization

APPENDIX 8

obligatory

Headquarters

________________________________________

Installation organization (trust, management)

________________________________________

Object name

Journal 1 wrench calibration for tensioning high-strength bolts with force control by the angle of rotation of the nut or by axial tension

________________

1 The magazine is issued for all wrenches used when making field connections at each object, designed to tension high-strength bolts according to the angle of rotation of the nut or according to axial tension.

When calibrating wrenches, the magazine must be kept by the responsible person performing the work.

The responsible person fills in the journal after each control calibration of the wrenches.

The log is kept until the delivery of the object.

the date	Change	Excess pressure of compressed air at the wrench inlet, Pa	Set of plates in a tight bag	Key for initial tension	Angle of rotation of the nut with a wrench	Signature of the responsible person who performed the calibration

In this journal, _________________ pages are laced and numbered

Place of printing

assembly

organizations

Content

1. General Provisions

2. Technical requirements

3. Content technological process

4. Acceptance rules and control methods

5. Safety requirements

Applications

1. An example of calibration of a torque wrench type KTR-3

2. Methods for tensioning high-strength bolts

3. Equipment for fire cleaning post

4. Equipment, mechanisms and tools used for processing contact surfaces, connected elements and tensioning high-strength bolts

5. Composition of adhesive friction coating

6. Journal of control over the implementation of field connections on high-strength bolts

7. Journal of control calibration of wrenches for tensioning and tension control of high-strength bolts

8. Journal of wrench calibration for tensioning high-strength bolts with control of efforts by the angle of rotation of the nut or by axial tension

APPROVE

Director___________________

___________ .___________________

1. GENERAL PROVISIONS

1.1. High-strength bolts, nuts and washers should be used in accordance with the instructions of the working (KM) or detailing (KMD) drawings of the steel structures of the object being mounted.

1.2. Projects for the production of works (PPR) must contain schemes for the production of works or technological maps, providing for the implementation of connections on high-strength bolts in the specific conditions of the object being mounted.

1.4. Fitters of at least 18 years of age who have undergone special theoretical and practical training, confirmed by a personal certificate for the right to perform these works, issued by the installation organization, are allowed to perform connections on high-strength bolts.

2. TECHNICAL REQUIREMENTS

2.1. Requirements for the materials used

2.2. Requirements for the connected structural elements and tools

2.2.1. The possibility of free supply of high-strength bolts and tightening of nuts using wrenches and torque wrenches must be ensured by the design of the connections.

2.2.2. Installation of connections is not allowed if there are burrs on the structural elements around and inside the holes, as well as along the edges of the elements.

The contact surfaces of the elements are not subject to priming and painting. The distance between the axis of the bolts of the last row and the primed surface should not be less than 70 mm.

2.2.4. In connections from rolled profiles with non-parallel surfaces of the flanges, leveling gaskets must be used.

2.2.5. The nominal diameters and blackness of the holes (mismatch of holes in individual parts of the assembled package) should not exceed the requirements specified in chapter SNiP III-18-75 “Rules for the production and acceptance of work. Metal constructions".

2.2.6. Control and calibration torque wrenches must be numbered, calibrated and provided with calibration charts or tables. Pneumatic and electric wrenches must meet passport requirements.

3.1. Preparatory operations

3.1.1. Preparatory operations include: depreservation and cleaning of high-strength bolts; preparation of structural elements; control and calibration check of the tool.

3.1.2. High-strength bolts, nuts, washers must be cleaned from factory preservation, dirt, rust and coated with a thin layer of grease. Re-preservation and cleaning are carried out according to the following technology.

3.1.3. Place high-strength bolts, nuts and washers weighing no more than 30 kg in a crate.

3.1.4. Immerse the lattice container filled with hardware into a tank with boiling water for 8-10 minutes (see drawing).

3.1.6. Place processed bolts, nuts and washers separately in closed boxes with handles with a capacity of not more than 20 kg to transfer them to the workplace.

3.1.7. On the portable container, indicate the standard sizes, the number of bolts, nuts and washers, the processing date, certificate and lot numbers.

3.1.8. Cleaned bolts, nuts and washers should be stored in closed boxes for no more than 10 days, after which it is necessary to re-process in accordance with paragraphs. 3.1.4 and 3.1.5.

3.1.9. Burrs found around and inside holes, as well as along the edges of elements, must be completely removed. Deburring around the holes and along the edges of the elements should be done with pneumatic or electric grinding machines without forming a recess that breaks the contact of the contacting surfaces, and in case of burrs inside the hole, with a drill, the diameter of which is equal to the diameter of the bolt.

3.1.10. If the difference in the planes of the elements to be connected is more than 0.5 to 3.0 mm inclusive, on the protruding element, it is necessary to make a bevel with a cleaning pneumatic or electric machine at a distance of up to 30.0 mm from the edge of the element. If the difference in planes is more than 3.0 mm, leveling pads should be used.

Device for boiling high-strength bolts, nuts and washers

1 - heating element; 2 - lattice container for bolts; 3 - water tank;

4 - drain plug

3.2. Basic technological operations

3.2.1. The main technological operations include:

Processing of contact surfaces;

Assembly of connections;

Installation of high-strength bolts;

Tension and tension control of bolts.

3.2.2. The method of processing the contact surfaces is selected in accordance with the coefficient of friction specified in the drawings KM or KMD, and chapter SNiP II-23-81 “Steel structures. Design standards".

The following methods of processing contact surfaces, performed at the assembly site, have been established: sandblasting (shot blasting); flame; metal brushes; glue-friction.

3.2.3. Sand blasting (shot blasting) treatment of the contact surfaces of the elements to be joined should be carried out with sand blasting or shot blasting machines in accordance with GOST 11046-69 (ST SEV 3110-81).

When sandblasting (shot blasting) processing of contact surfaces, mill scale and rust must be completely removed until a uniform light gray surface is obtained.

3.2.4. Flame treatment of contact surfaces must be carried out with wide-angle gas-flame burners GAO-60 or GAO-2-72 in accordance with GOST 17357-71.

Flame treatment is allowed with a metal thickness of at least 5.0 mm.

The speed of movement of the burner is 1 m/min with a metal thickness of more than 10 mm and 1.5-2 m/min - with a metal thickness of up to 10 mm inclusive.

Products of combustion and scale should be swept away with soft wire and then with hair brushes.

The surface after flame treatment must be free from dirt, paint, oil stains and easily peeling scale. Complete removal of mill scale is not necessary.

Flame treatment station equipment and brief technical specifications equipment are given in the recommended appendix 3.

3.2.5. Processing of contact surfaces with metal brushes should be carried out using pneumatic or electric grinders, the brands of which are indicated in the recommended appendix 4.

It is not allowed to bring the contact surfaces to be cleaned to a metallic sheen.

3.2.6. Adhesive friction coating on the contact surfaces of the pads, as a rule, is applied at the manufacturing plants of metal structures.

The technological process for obtaining adhesive friction coating provides for:

Processing of contact surfaces of pads in sandblasting (shot blasting) machines according to GOST 11046-69 (ST SEV 3110-81);

Application of epoxy-polyamide glue to the treated contact surfaces of the overlays;

Application of carborundum powder over uncured adhesive.

The safety of the adhesive-friction coating must be ensured by packing the slips for the entire period of their loading, transportation, unloading and storage at the construction and installation site.

The shelf life of slips with adhesive friction coating is not limited.

The composition of the adhesive friction coating is given in the recommended appendix 5.

The contact surfaces of the main connected elements before assembly must be treated with metal brushes in accordance with clause 3.2.5.

3.2.7. Metallization processing of the contact surfaces of the structural elements to be joined (galvanizing, aluminizing), as a rule, is carried out at the manufacturing plants of metal structures.

Surfaces treated by sandblasting (shot blasting) can be cleaned with a gas-flame method during re-treatment.

3.2.9. Contact surfaces without treatment should be cleaned of dirt and flaking scale with metal brushes; from oil - unleaded gasoline, from ice - chipping.

3.2.10. The assembly of connections on high-strength bolts includes the following operations:

Alignment of holes and fixation in the design position of the connection elements using assembly plugs, the number of which should be 10% of the number of holes, but not less than 2 pieces;

Installation of high-strength bolts in holes free from assembly plugs;

Tight package tie;

Tension of installed high-strength bolts to the force specified in the KM and KMD drawings;

Removing assembly plugs, placing high-strength bolts in the released holes and tensioning them to the design force;

Connection priming.

3.2.11. Under the heads and nuts of high-strength bolts, it is necessary to put only one heat-treated washer in accordance with GOST 22355-77.

The protruding end of the bolt must necessarily have at least one thread above the nut.

3.2.12. If the holes do not match, they should be drilled in elements with machined surfaces without using coolants.

3.2.13. Preliminary and final tension of high-strength bolts must be carried out from the middle of the connection to the edges or from the most rigid part of the connection towards its free edges.

3.2.14. The method of tensioning high-strength bolts must be indicated in the KM or KMD drawings.

3.2.15. In the absence of instructions, the tensioning method is selected by the installer according to the recommended appendix 2.

4. RULES OF ACCEPTANCE AND METHODS OF CONTROL

4.2. The responsible person (foreman, foreman), after inspection and verification, must present the finished connection to the customer's representative. In the absence of comments from the customer, the connection should be considered accepted and the responsible person enters all the necessary information about it in the journal for performing field connections on high-strength bolts (see mandatory Appendix 6).

4.3. After acceptance, the finished joint should be primed and painted. Grades of primer and paintwork material are accepted according to the "List of polymeric materials and products approved for use in construction", approved by the USSR Ministry of Health, the same as for priming and painting metal structures. Primer and paint grades must be indicated in the KM and KMD drawings.

4.4. The quality of the connections on high-strength bolts is checked by the person in charge by step-by-step control. Subject to control:

Quality of processing of contact surfaces;

The presence of washers under the heads of bolts and nuts;

The presence on the heads of the bolts of the brand of the manufacturer;

The length of the protruding part of the bolt thread above the nut;

The presence of the stigma of the foreman in charge of the assembly of the compound.

4.6. The compliance of the bolt tension with the design one is checked depending on the tension method. The deviation of the actual torque from the torque specified in the KM and KMD drawings should not exceed 20%.

Bolts with marks outside the specified limits must be loosened and re-tightened.

4.7. The tension of high-strength bolts is checked with a calibrated torque wrench or a control calibrated wrench.

The tension of the bolts should be controlled by a spot check: with the number of bolts in the connection up to 5 inclusive, 100% of the bolts are controlled, with the number of bolts from 6 to 20 - at least 5, with a larger number - at least 25% of the bolts in the connection.

4.9. The density of the package to be tightened is controlled by 0.3 mm probes. The probe should not pass between the planes along the contour of the connected elements.

4.10. Documentation presented upon acceptance of the finished object, except for the documentation provided for by chapter SNiP III-18-75 “Rules for the production and acceptance of work. Metal structures”, should contain:

Journal of assembly connections on high-strength bolts;

Certificates for bolts, nuts and washers;

Certificates for materials for the formation of adhesive friction coatings.

5. SAFETY REQUIREMENTS

5.1. The organization of a site for pre-assembly of structures with field connections on high-strength bolts should ensure the safety of workers at all stages of the work.

Works on the installation of structures on high-strength bolts must be carried out in accordance with the PPR, which contains the following safety decisions:

Organization of workplaces and passages;

The sequence of technological operations;

Methods and devices for the safe work of installers;

Location and coverage of mounting mechanisms;

Ways of warehousing building materials and structural elements.

5.2. The placement of working equipment and the organization of workplaces must ensure the safety of evacuation of workers in emergency situations, taking into account current building codes.

5.3. All work at height on the implementation of field connections on high-strength bolts should be carried out from scaffolds that provide free access to the connection with the tool.

Scaffolding and other devices that ensure the safety of work must comply with the requirements of chapter SNiP III-4-80 “Rules for the production and acceptance of work. Safety in construction”, GOST 12.2.012-75, GOST 24259-80 and GOST 24258-80.

5.4. Electrical safety at the installation site must be ensured in accordance with the requirements of GOST 12.1.013-78.

5.6. The place of production of sandblasting (shot blasting) works should be fenced off and appropriate warning signs and inscriptions should be hung around it.

5.7. Materials for sandblasting (shot blasting) surface treatment (sand, shot, metal sand) should be stored in containers with tightly closed lids.

5.8. The operator of the sandblasting (shot-blasting) apparatus and the auxiliary worker are supplied with space suits or helmets with a forced supply of clean air.

5.9. The air supplied to the suit must first be passed through a filter to remove dust, water and oil.

5.10. Between the workplaces of the operator and the auxiliary worker, located near the sandblasting (shot-blasting) apparatus, an audible or light alarm must be provided.

5.11. When processing contact surfaces with metal brushes (manual and mechanical), workers must be provided with goggles in accordance with GOST 12.4.003-80 or masks, gloves and respirators.

5.12. When processing contact surfaces with a gas-flame method, it is necessary to comply with the requirements of chapter SNiP III-4-80 “Rules for the production and acceptance of work. Safety in construction”, as well as sanitary rules for welding and cutting metals, approved by the USSR Ministry of Health.

5.14. It is not allowed to carry out work on flame treatment of the surfaces of structural elements in rainy weather outdoors without a canopy.

5.15. When performing flame treatment of contact surfaces, workers must be provided with goggles closed type with glass-light filters of grades G-1 or G-2.

Auxiliary workers must be provided with goggles with light filter glasses of grades B-1 or B-2.

5.17. The preparation of glue and the application of adhesive friction coatings should be carried out in a separate room equipped with exchange and local ventilation.

5.18. Persons working with epoxy resins must be provided with overalls and gloves.

To protect the skin from the effects of epoxy resins, protective pastes and ointments based on lanolin, petroleum jelly or castor oil should be used.

5.19. The room for applying glue-friction coatings must be provided with fire extinguishers - carbon dioxide and foam fire extinguishers.

5.20. Re-preservation of bolts, nuts and washers should be carried out in an open area with a canopy.

5.25. The working regime when working with manual electric and pneumatic machines and wrenches should be established in accordance with the "Recommendations for the development of the Regulations on the working regime of workers in hazardous occupations", approved in December 1971 by the All-Union Central Council of Trade Unions, the USSR Ministry of Health, the State Committee of the Council of Ministers of the USSR on labor issues and wages, as well as manufacturers' instructions for performing work with specific types of machines.

5.26. Priming and painting of finished joints on high-strength bolts should be carried out at the site for assembling metal structures.

5.27. Only workers who know the rules for the safe handling of the equipment and materials used and are familiar with the fire safety rules are allowed to work on the priming of the connections.

An example of calibration of a torque wrench type KTR-3 1

_________________

1 KTR-3 keys are manufactured by assembly organizations according to the drawings of the Central Research Institute of Projects of Steel Construction.

At a fixed point at the end of the key, a weight of mass is suspended

where M h- estimated twisting moment;

D M h- a moment equal to the product of the mass of the key and the distance from the center of gravity to the axis of the mandrel or bolt;

l- distance from the center of gravity of the load to the axis of the mandrel or bolt.

With a suspended load, the reading is carried out according to a recording device, for example, a dial indicator IC 10 mm according to GOST 577-68. The measurement is carried out 2-3 times until a stable result is obtained. Calibration results are recorded in the log of control calibration of keys (see mandatory Appendix 7).

Torque wrench calibration scheme

1 - welded hexagon or tightened high-strength bolt;

2 - rigid support; 3 - indicator; 4 - calibrated key; 5 - calibrated cargo

High Strength Bolt Tensioning Methods

1. Tensioning of high strength bolts by torque

1.1. The tension of high-strength bolts to the design force should be done by tightening the nuts with a torque wrench to the calculated value of the torque. Torque value M h required for tensioning high-strength bolts is determined by the formula:

M h = kPd,

k- the average value of the tightening factor for each batch of bolts according to the certificate or set using control devices at the installation site;

R- bolt tension force specified in the KM and KMD drawings;

d- the nominal diameter of the bolt.

1.2. To pre-tighten the nuts, use the pneumatic or electric nutrunners specified in recommended Appendix 4 and torque wrenches.

1.3. When tightening the bolt, the head or nut should be kept from turning with a mounting wrench. If turning does not stop as the bolt is tightened, the bolt and nut must be replaced.

1.4. The twisting moment should be recorded during the movement of the key in the direction that increases the tension.

Tightening should be done smoothly, without jerks.

1.5. Torque wrenches must be numbered and calibrated. They should be calibrated at the beginning of the shift.

2. Tensioning of high-strength bolts according to the angle of rotation of the nut

2.1. High-strength bolts must be installed in holes free from assembly plugs and tightened with a wrench adjusted to a torque of 800 N × m. Each bolt must be tightened until the nut stops rotating. After removing the assembly plugs and replacing them with bolts, the latter must be tightened to a tightening torque of 800 N × m.

2.2. To control the angle of rotation of the nuts, it is necessary to mark them and the protruding ends of the bolts with a combined center punch (see drawing) or paint.

Combined center punch

1 - center punch; 2 - nut; 3 - high-strength bolt; 4 - package

2.3. The final tightening is carried out with a wrench adjusted to a tightening torque of 1600 N × m, while the nut must turn through the angle indicated in the table.

3. Calibration of wrenches according to the angle of rotation of the nut

3.1. Nut runners should be calibrated on a special calibration package consisting of three bodies with at least 20 holes.

High-strength bolts are inserted into the holes of the calibration package and tightened with a wrench until the nut stops rotating. A group of bolts (calibration bolts) in the amount of at least 5 pcs. do not tighten.

The calibration bolts must be hand-tightened with an assembly wrench with a handle length of 0.3 m to failure (initial position).

3.2. On the prepared calibration bolts, the wrench is calibrated.

3.3. The compressed air pressure is set so that when the nut is turned through an angle of 180 ± 30 ° from its original position, the wrench will fail.

The air pressure must be checked periodically.

Air pressure control should be carried out according to the GOST 2405-72 pressure gauge installed at the point where the wrench hose is connected to the line.

3.4. When calibrating a wrench (to monitor the angle of rotation of the nut), marks must be applied to its replaceable head.

3.5. The impact wrench is considered calibrated if the angle of rotation of the nut in the process of tightening all the bolts at the moment of failure of the impact wrench is 180 ± 30°.

3.6. The results of the wrench calibration must be recorded in the wrench calibration log (see mandatory appendix 8).

3.7. In the event of a change in compressed air pressure after the repair of the defect in the wrench, it is necessary to perform a control calibration.

APPENDIX 3

Fire cleaning post equipment

equipment identification	Brief technical characteristics
Burner GAO-60, GAO-2-72 GOST 17357-71 (1 pc.)	Wide-cut, multi-flame, 100 mm wide.
Oxygen cylinders (3 pcs.)
Acetylene cylinders (2 pcs.)
Reducer balloon oxygen DKD15-65 or RKD-15-81	Maximum overpressure at the inlet - 1962 × 10 4 Pa; operating overpressure - 78.48 × 10 4 Pa; throughput at maximum pressure - 23 m 3 / h
Reducer balloon acetylene RD-2AM, DAP-1-65	The maximum overpressure at the inlet is 245.25 × 10 4 Pa; operating overpressure - from 0.981 × 10 4 Pa to 14.715 × 10 4 Pa; throughput - 5 m 3 / h
Rubber-fabric sleeves for oxygen supply (GOST 9356-75) with an inner diameter of 9.0, an outer diameter of 18 mm	Operating overpressure 147.15 × 10 4 Pa

APPENDIX 4

Equipment, mechanisms and tools used for processing contact surfaces, connected elements and tensioning high-strength bolts

The vibration levels of electric and pneumatic hand grinders and wrenches (Table 1) do not exceed those established in GOST 16519-79 (ST SEV 716-77) and GOST 12.1.012-78.

Table 1

Name	Brand, standard	Purpose
Electric impact wrenches		For tightening high-strength bolts during installation and assembly work
Pneumatic impact wrenches	GOST 15150-69 GOST 10210-74
wrenches		For pre-assembly connections
Electric hand grinders		For cleaning work
Electric Angle Grinders
Pneumatic hand grinders		For the cleaning metal surfaces from rust and scale
Gas burners	GOST 17357-71	For processing contact surfaces

Noise levels of electric and pneumatic hand grinders and wrenches do not exceed those specified in GOST 12.1.003-76. Vibration parameters and noise characteristics of electric and pneumatic hand-held machines used in the processing of contact surfaces of the elements to be connected and for tensioning high-strength bolts are given in Table 1, respectively. 2 and 3.

table 2

Vibration parameters



Logarithmic levels of vibration velocity values, dB

Table 3

Noise characteristics

	Geometric mean frequencies of octane bands, Hz

	Sound power level, dB

The composition of the adhesive friction coating

Name		Cooking method
Epoxy-polyamide adhesive	Epoxy resin ED-20 according to GOST 10587-76 (100 wt. h)	AT epoxy resin introduce hardener and accelerator; the resulting mixture is thoroughly mixed
	Hardener I-5M (I-6M) according to VTU OP-2382-65-60 (50 wt. h) Accelerator UP-606-2 according to MRTU 6-09-6101-69 (2 - 3 wt. h)
abrasive material	Carborundum powder grade KZ or KCh
Solvent	Acetone according to GOST 2768-79

6.2.16.1 The tightening of bolted connections of the nodal plates of aluminum dome roofs is checked when dismantling the cards for the inspection of beams and supporting crowns (table 6.4, lines 12 and 27 and table 6.5, line 20). Additionally, the tightening of bolted connections in four nodal plates is checked according to the scheme shown in Figure 6.18.

Figure 6.18 - Scheme of places for dismantling the nodal caps (view of the domed roof from above)

6.2.16.2 Tightening must be dismantled prior to inspection. protective caps and a visual inspection of the bolted connection was carried out. On the surface of bolts, nuts and washers there should be no cracks, scale, rust, burrs, dents and nicks on the thread. Bolts must be marked with the temporary resistance, symbol melting number, the manufacturer's stamp is affixed, the marking of the bolts of the climatic modification HL (according to GOST 15150) must contain the designation "HL".

6.2.16.3 The tightening of bolted connections is checked by measuring the tightening torque with a torque wrench and a feeler gauge. The number of controlled bolted connections in the assembly must be at least:

With the number of bolts in the connection up to four - all bolts;

From five to nine - at least three bolts;

From 10 and more - 10% of bolts, but not less than three in each connection.

If one bolted connection with abnormal tightening is detected
(Subclause 6.2.16.6), twice the number of bolted connections is subject to control. If, upon re-checking, one bolt with abnormal tightening is found, all bolts in all controlled nodes should be checked to bring the torque of each to the required value.

6.2.16.4 For tightening control threaded connections with a controlled tightening torque of high-strength bolts of the upper nodal plates, torque wrenches of scale and limit types and probes are used that meet the requirements given in table 6.10.

Table 6.10 - Requirements for the means of control of bolted connections

Torque wrenches to control the tightening of high-strength bolts must be calibrated at least once per shift in the absence of mechanical damage, and also after each replacement of the control measuring instrument or repair of the key, in accordance with SNiP 3.03.01-87 (clause 4.27).

6.2.16.5 Before testing the bolted connection, it is necessary to set the torque wrench on the torque wrench, set in the project documentation, upon reaching which a click will occur. In the absence of data established in the design documentation, the torque M, N m, is determined by the formula:

M = K∙P∙d, (6.11)

where K is the average value of the torque factor, set for each batch of bolts in the manufacturer's certificate or determined at the installation site using control measuring instruments. For bolts according to GOST R 52644 K = 0.18;

P is the calculated bolt tension specified in the working drawings, N (kgf). In the absence of design data, the design bolt tension is determined in accordance with SNiP 2.03.06-85, 8.10 using the formula:

Р = Rbh×Abn , (6.12)

where R bh is the design tensile strength of a high-strength bolt, is determined by the formula:

Rbh = 0.7∙Rbun , (6.13)

where R bun is the smallest tensile strength of the bolt, taken according to
SNiP II-23-81* (table 6.1) and given in table 6.12.

A bn - bolt cross-sectional area, taken in accordance with GOST 9150, GOST 8724 and
GOST 24705 taken from the values given in SNiP II-23-81* (see table 6.2) and are given in table 6.11.

Table 6.11 - The value of the smallest tensile strength of the bolt

Table 6.12 - Cross-sectional areas of bolts

d, mm
A bn , cm 2	1,57	1,92	2,45	3,03	3,52	4,59	5,60	8,16	11,20	14,72

6.2.16.6 The criterion for the tightening of a bolted joint is the absence of rotation of the nut or bolt.

6.2.16.7 Tie tightness of the top knot and aluminum profile, at the joints, should be checked with a probe 0.3 mm thick, which should not pass between the assembled parts to a depth of more than 20 mm according to (SNiP 3.03.01-87). The scheme for checking the junction of the upper nodal plate and the aluminum profile with a probe is shown in Figure 6.19.