Fire alarm systems. Features of preschool and school furniture Must be less than 0
This offset is calculated by the formula:
dU = U(I) tzi – U(0) tze,(11.1)
where U(I) tzi is the measured potential difference between the pipe and the ground (after turning on the cathode polarization and three-hour polarization);
U(0) mze is the natural potential difference between the pipe and the ground (measured before switching on the cathodic polarization).
If a the controlled section with a length of more than 4 km is located in the area of stray currents, then the measured potential difference offset must be at least 0.5 V. For a short section (from 200 m to 4 km) located in the area of stray currents, the measured potential difference mixing pipe-to-ground must be at least 0.8 V.
The control current is determined for the length of the entire test section minus the length of the total length of the air transitions in this section.
In case of obtaining positive results of testing a pipeline section by the cathodic polarization method, the tested section may be fully or partially subjected to secondary control as part of a larger section into which it entered. In the event that this larger area shows unsatisfactory insulation quality, then the search for defects should be carried out only on those parts of the area that have not been tested before.
Quality control of the insulating coating of pipelines can be performed by a specialized contractor.
On the controlled area, through defects of the insulating coating should be localized and repaired.
The controlled section should not have electrical and technological jumpers with other structures, including those with their own metal casings at crossings over roads and railways. It is also not allowed to contact the uninsulated ends of the controlled area with the ground, building structures, including concrete-based structures.
Throughout the controlled section of the pipeline, in accordance with the project, control and measuring points (CIP) should be installed. If the instrumentation is not installed, then such a site is considered not prepared for testing.
The polarizing current source is connected only after a preliminary measurement of the natural (potential of free corrosion potentials) at the end of the controlled area.
Either a 12 or 24 V battery or a stabilized DC power supply must be used as a polarizing current source.
A polarization current stabilizer must be included in the circuit of any current source to stabilize and regulate the polarization current.
To measure the polarization current and potential difference during cathodic polarization, self-recording or recording devices with an internal resistance of at least 10 MΩ should be used.
When the controlled area is located in the zone of action of stray currents, to measure the potential difference during cathodic polarization, self-recording or recording devices with an internal resistance of at least 10 MΩ should be used.
Connect the polarization current stabilizer with wires to a direct current source, observing the polarity. The polarization current stabilizer must be connected with a "minus" to the pipeline, and a "plus" - to the temporary AZ.
Temporary grounding should be used solely for the purpose of cathodic polarization of the pipeline section.
For temporary grounding equipment, rod or screw electrodes are used. The transient resistance of temporary grounding should be no more than the value given in table 11.2.
Table 11.2 - Spreading resistance of temporary grounding, Ohm
Temporary AZ must be installed below the freezing of the soil to a depth of at least 0.3 m.
Temporary grounding is located in places with the lowest possible electrical resistivity of the soil at a distance of 100 to 400 m from the pipeline.
The specified distance depends on the length of the controlled section and must comply with Table 11.3.
Table 11.3 - Distance to the location of temporary grounding
If the tested section of the pipeline is under cathodic (including temporary) protection (galvanic, using jumpers or in another way), then this protection must be turned off at least three days before measuring the natural pipe-to-ground potential difference, and the jumpers are open.
Tests are carried out in the following sequence:
a) Measure the natural potential difference pipe-ground at the end of the section. During measurements, the DC source must be turned off.
b) Turn on the DC source, set the required current strength (monitoring current density (mA / km) of the insulation state, depending on the length of the controlled section and the required insulation resistance value, is determined according to Table A1 of Appendix A RD-29.035.00-KTN-080-10 ).
c) Measure the potential difference pipe-ground at the end of the controlled section and determine the potential shift. If this offset is less than the specified one, then the control current is increased until the required offset is obtained.
d) This current is maintained constant throughout the entire test period using a polarization current stabilizer, either by reducing the spreading resistance of the temporary AZ, or by changing the voltage of the power source, or by a combination of any of the above methods.
e) After at least 3 hours of polarization, measure the potential difference between the pipe and the ground at the end of the section, carry out calculations and fill in the act of assessing the condition of the pipeline insulation (Appendix I). Data of the recorders in graphic form and in electronic form in the development format on CD disks are attached to the act of assessing the condition of the coating.
Ground freezing control
The depth of soil freezing is controlled by field measurement of soil temperature.
Ground temperature should be expressed in degrees Celsius rounded to the nearest 0.1 °C. The temperature of the beginning of soil freezing is 0 °C and below. Measurement of soil temperature must be carried out by a certified, verified pyrometer (thermal imager).
Soil temperature measurement should be carried out in the pit:
Above the axis of the pipeline vertically from the ground surface (excluding vegetation cover) to the upper generatrix of the pipeline and from the lower generatrix of the pipeline to a depth of 0.3 m in increments of 0.1 m;
At the installation site of the VAZ, the soil temperature is measured in increments of 0.1 m to a depth of 1 m. The VAZ must be installed below the freezing of the soil to a depth of at least 0.3 m.
The results of measuring the soil temperature are recorded in the act of assessing the condition of the pavement completed by the construction of the (operated) section of the MP.
11.1 Security questions
1. For sections of what length is cathodic polarization carried out?
2. Readiness of the site for carrying out cathodic polarization.
3. Equipment for carrying out cathodic polarization.
4. Scheme and procedure for carrying out cathodic polarization.
5. Presentation of the results of the cathodic polarization.
Fire safety of warehouses
In ensuring the fire safety of storage facilities, the specialization of the warehouse plays an important role, whether it is intended for storing food or non-food products, or it is used for storing dangerous types of goods: toxic and flammable. That is why on the territory of any warehouse there must be special means of preventing and extinguishing fires (fire extinguishers, fire and smoke detectors, fire hydrants). In addition, it is important to remember and be aware of the conditions that will help reduce the risk of an emergency. In accordance with the Code of Rules "Determination of categories of premises, buildings and outdoor installations for explosion and fire hazard" (SP 12.13130.2009) For explosion and fire hazard of premises are subdivided into categories A, B, C1-C4, D and D, and buildings - into categories A, B, C, D and D, according to table 1.
Table 1
|
Characteristics of substances and materials, |
|
|
increased fire and explosion hazard |
Combustible gases, flammable liquids with a flash point of not more than 28 ° C in such an amount that they can form explosive vapor-gas-air mixtures, the ignition of which develops an estimated excess explosion pressure in the room exceeding 5 kPa, and (or) substances and materials that can explode and burn when interacting with water, atmospheric oxygen or with each other, in such an amount that the calculated overpressure of the explosion in the room exceeds 5 kPa |
|
fire and explosion hazard |
Flammable dusts or fibres, flammable liquids with a flash point of more than 28 °C, flammable liquids in such quantity that they can form explosive dust-air or vapor-air mixtures, the ignition of which develops an estimated overpressure of the explosion in the room exceeding 5 kPa |
|
fire hazard |
Combustible and slow-burning liquids, solid combustible and slow-burning substances and materials (including dust and fibers), substances and materials that can only burn when interacting with water, atmospheric oxygen or with each other, provided that the premises in which they are located (contact), do not belong to category A or B |
|
moderate fire hazard |
Non-combustible substances and materials in a hot, incandescent or molten state, the processing of which is accompanied by the release of radiant heat, sparks and flames, and (or) combustible gases, liquids and solids that are burned or disposed of as fuel |
|
reduced fire hazard |
Non-flammable substances and materials in a cold state |
In addition, general-purpose warehouses are divided into open (platforms, platforms), semi-closed (sheds) and closed (heated and unheated). The main type of storage facilities are closed warehouses. To determine the admissibility of storing certain substances and material assets in them, the degree of fire resistance, as well as the classes of constructive and functional fire hazard, must be taken into account. The degree of fire resistance of a building is determined by the fire resistance of its building structures, the structural fire hazard class of a building is determined by the degree of participation of building structures in the development of a fire and the formation of its dangerous factors, and the functional fire hazard class of a building and its parts is determined by their purpose and features of the technological processes used.
Federal Law No. 123-FZ dated July 22, 2008 "Technical Regulations on Fire Safety Requirements" (hereinafter referred to as the Technical Regulations) defines the degrees of fire resistance of buildings - I, II, III, IV, V, four classes of constructive fire hazard - C0, C1, C2 and C3 (non-flammable, low flammable, moderately flammable, flammable). According to the functional fire hazard, buildings are divided into five classes F1, F2, F3, F4, F5, depending on the methods of their use and the threat to human life. Warehouse buildings (parts of buildings) belong to class F5.2.
The minimum distance between the stack (rack) and the wall (column, protruding structure, heating appliances) must be at least 0.7 m, between the stack (rack) and the ceiling (truss or rafters) - 0.5 m, between the stack and the lamp - 0.5 m, between the luminaire and the combustible structure - 0.2 m.
In sectionless warehouses or sections with a width of up to 30 m and an area of not more than 700 m2, a passage with a width of at least 1.5 m must be left against evacuation exits (doorways). In warehouses with an area of more than 700 m2, in addition, a passage with a width of at least 1 .5 m along the warehouse premises. On the floor of the warehouse, clear lines highlight areas for storing materials and goods, taking into account longitudinal and transverse aisles, emergency exits and access to fire extinguishing equipment. It is not allowed to place longitudinal and transverse aisles with the location of warehouse columns on them. It is forbidden to use aisles and gaps between stacks, even for temporary placement of goods, inventory and cushioning material.
The gaps between stacks or racks are determined by the relevant technological instructions. For example, when placing tires on the racks of warehouses, the longitudinal passage must be at least 1.2 m, and the transverse passages against the evacuation doors must be at least 4.5 m. The number of transverse passages is determined depending on the length of the warehouse at the rate of every 25 m between the axles doorways, but no further than 25 m from the transverse walls.
Joint storage in the same section (sectionless warehouse) with rubber or tires of other materials, regardless of the uniformity of the fire extinguishing agents used, is not allowed.
In warehouses for the storage of cotton fiber, wool, tarpaulin, bags, the longitudinal passage and passages against the doors must be at least 2 m wide. In height, the distance from the top of the bales to electric lamps and electrical wiring must be at least 1 m. more than six wagon lots with a capacity of not more than 300 tons) must be separated by aisles. In sections or non-sectional warehouses where cotton fiber, wool, bags, tarpaulin are stored, it is not allowed to store other combustible materials or goods.
This requirement is also valid for warehouses (sections) where reactive metals are stored, as well as metals or concentrates in combustible containers (packaging).
For the storage of natural rubber, cotton fiber, and reactive metals, storage facilities are used that are not lower than the II degree of fire resistance, for the storage of synthetic rubber and tires - not lower than the III degree of fire resistance.
The distances between buildings, structures and structures (hereinafter referred to as buildings) on the territory of production facilities, depending on the degree of fire resistance, the class of constructive fire hazard and the category for explosion and fire hazard, should be taken not less than those indicated in Table 2.
table 2
|
Degree |
Distances between buildings, m |
||
|
I and II degree |
III degree |
III degree of fire resistance |
|
|
I and II degree |
Not standardized | ||
|
III degree | |||
|
III degree | |||
NOTE The smallest distance between buildings is considered to be the clear distance between external walls or structures. In the presence of building structures protruding by more than 1 m and made of materials of group G1 - G4, the distance between these structures is considered the smallest distance.
The distance between buildings is not standardized:
a) if the sum of the floor areas of two or more buildings of III and IV degrees of fire resistance of classes C1, C2 and C3 does not exceed the floor area allowed between the fire walls, counting according to the most fire hazardous category, the lowest degree of fire resistance and the lowest class of constructive fire hazard of the building;
b) if the wall of a taller or wider building or structure facing another building is type 1 fireproof;
c) if buildings and structures of the III degree of fire resistance, regardless of the fire hazard of the premises located in them, have opposing fire walls of the 2nd type with filling of openings of the 2nd type.
The specified distance for buildings I, II, as well as III and IV degrees of fire resistance of class C0 of categories A, B and C is reduced from 9 to 6 m, subject to one of the following conditions:
buildings are equipped with stationary automatic fire extinguishing systems;
specific fire load in category B buildings is less than or equal to 10 kg per 1 sq. m floor area.
Distances from closed warehouses of flammable and combustible liquids to other buildings and structures should be taken in accordance with.
In fire barriers separating rooms of categories A and B from rooms of other categories, corridors, stairwells and elevator lobbies, lobbies with constant air overpressure should be provided according to the Code of Rules “Heating, ventilation, air conditioning. fire safety requirements. The device of common vestibules for two rooms or more of the specified categories is not allowed ”(SP 7.13130.2009).
The device of common vestibules for two rooms or more of the specified categories is not allowed.
If it is impossible to install tambour locks in fire barriers that separate rooms of categories A and B from other rooms, or doors, gates, hatches and valves - in fire barriers that separate rooms of category C from other rooms, a set of measures should be provided to limit the spread of fire and penetration of combustible gases, vapors of flammable and combustible liquids, dust, fibers capable of forming explosive concentrations into adjacent floors and rooms. The effectiveness of these measures must be justified.
In the openings of fire barriers that cannot be closed by fire doors or gates, for communication between adjacent rooms of categories C, D and D, it is allowed to provide open vestibules equipped with automatic fire extinguishing installations. The enclosing structures of these vestibules must be fireproof.
In rooms of class F5.2 of categories A, B and C1, in which flammable liquids are used or stored, the floors should be made of non-combustible materials or materials of the G1 combustibility group.
When designing administrative and amenity premises and buildings up to 50 m high (including the attic floor) of warehouse facilities, the provisions of this section, presented below, should be used.
When designing buildings rebuilt in connection with the expansion, reconstruction or technical re-equipment of enterprises, deviations from the requirements of these standards in terms of geometric parameters are allowed.
Built-in premises should be made, as a rule, from lightweight enclosing structures, including collapsible ones, and placed dispersed.
In buildings of the IV degree of fire resistance of classes C2 and C3, built-in premises (with the exception of latrines, personal hygiene for women, hand baths, drinking water supply devices, washbasins and half-showers) are not allowed to be placed near the outer walls, on mezzanines and technological platforms.
The height of the built-in premises (from floor to ceiling) is allowed to be at least 2.4 m.
Administrative and household premises can be located in the extensions of buildings.
Annexes of I and II degrees of fire resistance should be separated from buildings of I and II degrees of fire resistance by fire partitions of the 1st type.
Extensions below the II degree of fire resistance, as well as extensions to buildings below the II degree of fire resistance and extensions to rooms and buildings of categories A and B should be separated by fire walls of the 1st type.
Annexes of IV degree of fire resistance of class C0 are allowed to be separated from buildings of IV degree of fire resistance of classes C0 and C1 by fire walls of the 2nd type.
Administrative and amenity premises can be located in inserts and extensions of buildings of categories C, D and D:
I, II, and III degrees of fire resistance of fire hazard class C0;
IV degree of fire resistance of all fire hazard classes.
Inserts should be separated from the premises by fire walls of the 1st type.
Inserts from rooms of categories C, D, and D are allowed to be separated:
in buildings of I, II degrees of fire resistance of classes C0 and C1, III degrees of fire resistance of class C0 with fireproof partitions of the 1st type;
in buildings of III degree of fire resistance of class C1 and IV degree of fire resistance of classes C0 and C1 - fire walls of the 2nd type.
Buildings should be taken with a number of floors no more than two and separated from the premises by fire walls and floors of the 1st type.
Buildings from premises of categories C, D and D are allowed to be separated:
in buildings of I, II degrees of fire resistance of classes C0 and C1, III degrees of fire resistance of class C0 - fire partitions of the 1st type and ceilings of the 2nd type;
in buildings of III degree of fire resistance of class C1 and IV degree of fire resistance of classes C0 and C1 - fire walls of the 2nd type and fire ceilings of the 3rd type.
The total area of inserts allocated by fire partitions of the 1st type and fire walls of the 2nd type, as well as built-ins and storage facilities, should not exceed the area of the fire compartment established in the Code of Rules “Fire Protection Systems. Ensuring fire resistance of protected objects” (SP 2.13130.2012).
Corridors should be divided by fire partitions of the 2nd type into compartments with a length of not more than 60 m.
In buildings of I and II degrees of fire resistance with a number of floors of no more than three, it is allowed to design the main stairs open to the entire height of the building, provided that the remaining (at least two) stairs are placed in ordinary staircases of the 1st type. At the same time, lobbies and floor halls, in which open staircases are located, must be separated from adjacent rooms and corridors by fireproof partitions of the 1st type.
Cladding and finishing of the surfaces of walls, partitions and ceilings of halls for more than 75 seats (except for halls in buildings of the V degree of fire resistance) should be provided from materials of combustibility groups of at least G2.
The degree of fire resistance, the class of constructive fire hazard, the height of buildings and floor area within the fire compartment should be taken according to SP 2.13130.2012, except where otherwise specified.
Multi-storey warehouse buildings of categories B and C should be designed with a width of no more than 60 m.
The area of the first floor of a multi-storey building is allowed to be taken according to the norms of a one-story building, if the ceiling above the first floor is type 1 fireproof.
Warehouse premises of categories B1 - B3 of industrial buildings should be separated from other premises by type 1 fire partitions and type 3 ceilings, when storing these products on high-rise racks - by type 1 fire walls and type 1 ceilings. At the same time, the premises of warehouses for finished products of categories B1 - B3, located in industrial buildings, should, as a rule, be located near the outer walls.
The area of grain storage buildings between fire walls should be taken no more than 3000 square meters. m.
Warehouses of raw materials of feed mills should be designed as one-story. Warehouses for finished products in the form of packaged goods (sacks and bags with flour, animal feed) can be designed multi-storey (no more than six floors).
In the container warehouse building on the ground floor at the end, it is allowed to have rooms for charging battery loaders.
The building envelope of the battery charging room must have an REI limit of 45 and a structural fire hazard class of K0.
The accumulator charging rooms must be separated from the rest of the storage rooms by type 2 fire walls and type 3 floors and have a separate exit.
Window openings of container cargo warehouses with production of category B should be filled with glass blocks, arranging opening window transoms with an area of at least 1.2 square meters in part of the openings. m with mechanized opening for smoke removal. The total area of the openings is assumed to be at least 0.3% of the floor area of the warehouse.
Receiving facilities for unloading bulk materials from railway and road transport category B for explosion hazard may be designed with bunkers located in recessed rooms with openings filled with easily dumped structures with an area of at least 0.03 sq. m per 1 cu. m of space. The area of these premises should not exceed 1000 square meters. m and the height is 6 m.
Auxiliary premises for service personnel should be located in separate buildings.
It is allowed to locate auxiliary premises in annexes at the end of industrial buildings on the side of placement of premises of categories B1 - B4, D or D (with the exception of grain cleaning departments of mills).
The largest allowable floor area between the fire walls of storage buildings for fertilizers and pesticides should be taken from table 3.
Table 3
|
Degree |
Floor area between fire |
|||
|
one-story |
two-storey |
multi-storey |
||
|
Not limited |
||||
When determining the floor area for storing ammonium nitrate (with the exception of waterproof nitrate), it should also be taken into account that between fire walls it is allowed to store no more than 5000 tons of nitrate in bulk and no more than 2500 tons of nitrate in special bags.
It is allowed to store up to 3500 tons of ammonium nitrate in special bags in separate storage buildings, separated by partitions made of material of the NG group with a fire resistance rating of at least R 45 into storage rooms for storing saltpeter in each of them in an amount of not more than 1750 tons.
Partitions separating warehouses for the storage of explosive and flammable pesticides from other premises must have a fire resistance rating of at least EI 45 and fire hazard class K0; doors in these partitions must have a fire resistance rating of EI 30.
Warehouses for the storage of ammonium nitrate in an amount not exceeding 1500 tons may be separated from other premises, including warehouses for fertilizers and pesticides, by solid (without openings) partitions made of material of the NG group with a fire resistance limit of at least EI 45.
Tobacco warehouses, as a rule, are located in separate one- or multi-storey buildings, designed to store a six-month supply of tobacco raw materials.
Warehouses of tobacco should be divided by fire walls into compartments no more than 1500 square meters. m, for warehouses of finished products - 750 sq. m.
Aerosol products of the 2nd and 3rd fire hazard levels should be stored, as a rule, separately from other goods in one-story warehouse buildings or fire compartments of such buildings. Storage in warehouses located in the basement and underground floors is not allowed.
When stored in a warehouse together with other combustible goods, the total amount of aerosol products of the 2nd and 3rd fire hazard levels should not exceed:
Aerosol packages of level 2 - 1100 kg;
Level 3 - 450 kg.
The total amount of aerosol products when stored in a warehouse together with other combustible goods can be increased if there is automatic water fire extinguishing and allocation of separate rooms or specially designated areas for aerosol products with a mesh fence (made of steel wire with a diameter of at least 3 mm, a cell size of not more than 50 mm ), excluding the expansion of cylinders in case of fire. The total amount of aerosol products of the 2nd and 3rd levels of fire hazard in this case should not exceed:
For outdoor storage - 5500 kg;
When stored on racks - 11000 kg.
In open areas or under sheds, storage of aerosol products of the 2nd and 3rd levels of fire hazard is allowed only in non-combustible containers. The distance from such storage places to buildings (structures) should be at least 15 m or at fire walls.
For aerosol products of the 1st level of fire hazard, fire safety requirements for placement and storage should be presented as for combustible goods.
The buildings of the warehouse for active ventilation and the floor storage should be designed as one-story, without attics.
The location of auxiliary premises in the floor storage building is not allowed.
In the oversilo and undersilo galleries connecting the working buildings of the elevators with the silo buildings, light enclosing structures (made of profiled galvanized steel or asbestos-cement sheets) should be provided. It is allowed to use other structures, but in combination with sections of easily dropped structures.
Warehouse buildings with high-rise rack storage of category B should be designed as one-story I-IV degrees of fire resistance of class C0.
Racks must have horizontal screens made of materials of the NG group with a height step of no more than 4 m.
Screens should cover the entire horizontal section of the rack, including the gaps between paired racks, and should not interfere with loading and unloading operations. Screens and bottoms of containers and trays shall have holes 10 mm in diameter, evenly spaced, with a square side of 150 mm.
The structures of ramps and canopies adjacent to buildings of I, II, III and IV degrees of fire resistance, fire hazard classes C0 and C1, should be taken from materials of the NG group.
In order to ensure timely and unhindered evacuation of people, rescue people who may be exposed to dangerous fire factors, as well as to protect people on evacuation routes from the effects of dangerous fire factors, when designing and operating warehouse buildings, it is necessary to be guided by the provisions of the Technical Regulations, as well as the Code of Practice of the "System fire protection. Escape routes and exits” (SP 1.13130.2009) and “Fire protection systems. Fire warning and evacuation control system. Fire safety requirements” (SP 3.13130.2009).
To determine the need to protect warehouse buildings with automatic fire protection systems, as well as when designing the necessary systems at protection facilities, it is necessary to be guided by the provisions of the Technical Regulations, as well as the Code of Practice “Fire Protection Systems. Fire alarm and fire extinguishing installations are automatic. Design norms and rules” (SP 5.13130.2009), “Fire protection systems. Electrical equipment. Fire safety requirements” (SP 6.13130.2009), “Heating, ventilation and air conditioning. Fire safety requirements” (SP 7.13130.2009), “Fire protection systems. Internal fire water supply. Fire safety requirements” (SP 10.13130.2009).
To determine the need to provide storage facilities with external fire water supply, as well as when designing these systems, it is necessary to be guided by the requirements of the Technical Regulations and the Code of Practice "SP 8.13130.2009" (Fire protection systems. Sources of external fire water supply. Fire safety requirements).
It should also be noted that in order to constantly ensure fire safety during the operation of objects of this category, it is necessary to comply with the requirements of the Rules for the fire regime in the Russian Federation, approved by Decree of the Government of the Russian Federation dated April 25, 2012 No. 390.
498. Substances and materials must be stored in warehouses (premises), taking into account their flammable physical and chemical properties (the ability to oxidize, self-heat and ignite when exposed to moisture, contact with air, etc.), signs of compatibility and uniformity of fire extinguishing agents in accordance with attachment no. 2.
Joint storage in the same section with rubber or tires of any other materials and goods, regardless of the uniformity of the fire extinguishing agents used, is not allowed.
499. Cylinders with GG, containers (bottles, large bottles, other containers) with flammable liquids and GZh, as well as aerosol packages must be protected from solar and other thermal effects.
500. Storage of aerosol packages in multi-storey warehouses is allowed in fire compartments only on the top floor, the number of such packages in a warehouse compartment should not exceed 150,000.
The total storage capacity should not exceed 900,000 packages. In general warehouses, storage of aerosol packages in the amount of not more than 5000 pieces is allowed. It is allowed to store no more than 15,000 packages (boxes) in an isolated compartment of the general warehouse.
501. In open areas or under sheds, storage of aerosol packages is allowed only in non-combustible containers.
502. In warehouses with rackless storage, materials must be stacked. Opposite the doorways of the storage facilities, there should be free passages with a width equal to the width of the doors, but not less than 1 m.
Every 6 m in warehouses, as a rule, longitudinal passages with a width of at least 0.8 m should be arranged.
503. The distance from lamps to stored goods must be at least 0.5 m.
504. Parking and repair of loading and unloading and transport vehicles in warehouses and landing stages are not allowed.
Cargoes and materials unloaded onto the ramp (platform) must be removed by the end of the working day.
505. In warehouse buildings, all operations related to opening containers, checking serviceability and minor repairs, packaging products, preparing working mixtures of flammable liquids (nitro-paints, varnishes, etc.) must be carried out in rooms isolated from storage areas.
506. Cars, engine trucks, auto-loaders and truck cranes and other types of lifting equipment should not be allowed to stacks, stacks and sheds where roughage, fibrous materials are stored, at a distance of less than 3 m if they have serviceable spark arresters.
507. The electrical equipment of warehouses at the end of the working day must be de-energized. Devices designed to disconnect the power supply of the warehouse must be located outside the warehouse on a wall made of non-combustible materials or on a free-standing support, placed in a cabinet or niche with a sealing device and locked with a lock.
508. Duty lighting in warehouse premises, as well as the operation of gas stoves, electric heaters and the installation of plug sockets are not allowed.
509. When storing materials in an open area, the area of one section (stack) should not exceed 300 m2, and fire gaps between the stacks should be at least 6 m.
510. Staff and other persons are not allowed to live in buildings located on the territory of bases and warehouses.
511. Entry of locomotives into warehouses of categories A, B and C is not allowed.
512. It is not allowed to store flammable liquids and combustible liquids in workshop storerooms in excess of the norms established at the enterprise. At workplaces, the amount of these fluids should not exceed the shift requirement.
513. It is not allowed to store combustible materials or non-combustible materials in combustible containers in the premises of the basement and basement floors that do not have windows with smoke extraction pits, as well as when connecting the common staircases of buildings with these floors.
514. Embankments around tanks, as well as crossings through them, must be in good condition. Areas within the embankment should be leveled and covered with sand.
operation of leaky equipment and valves;
operation of tanks with distortions and cracks, as well as faulty equipment, instrumentation, supply pipelines and stationary fire-fighting devices;
the presence of trees and shrubs in the square of embankments;
installation of containers on combustible or slow-burning bases;
overflow of tanks and cisterns;
sampling from tanks during the discharge or loading of oil and oil products;
draining and loading of oil and oil products during a thunderstorm.
516. Breathing valves and flame arresters must be checked in accordance with the technical documentation of manufacturers.
When inspecting breathing fittings, it is necessary to clean the valves and screens from ice. Warming them should be done only in fireproof ways.
517. Sampling and level measurement must be carried out using equipment that excludes sparking.
518. Storage in a container of liquids with a flash point above 120 degrees. C in an amount of up to 60 m3 is allowed in underground storages made of combustible materials, provided that the floor is made of non-combustible materials and the coating is backfilled with a layer of compacted earth with a thickness of at least 0.2 m.
519. Joint storage of flammable liquids and combustible liquids in containers in the same room is allowed if their total amount does not exceed 200 m3.
520. In storage facilities for manual stacking, barrels with flammable liquids and combustible liquids must be installed on the floor in no more than 2 rows, for mechanized stacking of barrels with combustible liquids - no more than 5, and flammable liquids - no more than 3.
The width of the stack should be no more than 2 barrels. The width of the main aisles for transporting drums should be at least 1.8 m, and between stacks - at least 1 m.
521. It is allowed to store liquids only in serviceable containers. Spilled liquid must be cleaned up immediately.
522. Open areas for the storage of petroleum products in containers must be fenced with an earth rampart or non-combustible solid wall at least 0.5 m high with ramps for access to the sites.
The sites should rise 0.2 m above the adjacent territory and be surrounded by a sewage ditch.
523. Within one bunded area, it is allowed to place no more than 4 stacks of barrels measuring 25 x 15 m with gaps between the stacks of at least 10 m, and between the stack and the shaft (wall) - at least 5 m.
Gaps between stacks of two adjacent platforms should be at least 20 m.
524. Sheds made of non-combustible materials are allowed above the sites.
525. It is not allowed to spill oil products, as well as store packaging material and containers directly in storage facilities and on bunded sites.
526. Windows of rooms where gas cylinders are stored must be painted over with white paint or equipped with non-combustible sun protection devices.
When storing cylinders in open areas, structures that protect them from exposure to precipitation and sunlight must be made of non-combustible materials.
527. Placement of group balloon installations is allowed at deaf (having no openings) external walls of buildings.
Cabinets and booths where cylinders are placed must be made of non-combustible materials and have natural ventilation, excluding the formation of explosive mixtures in them.
528. Cylinders with GH should be stored separately from cylinders with oxygen, compressed air, chlorine, fluorine and other oxidizing agents, as well as from cylinders with toxic gases.
529. When storing and transporting oxygen cylinders, oils (fats) and contact of the cylinder fittings with oiled materials should not be allowed.
When turning oxygen cylinders by hand, it is not allowed to take hold of the valves.
530. Gas storage rooms must have serviceable gas analyzers up to explosive concentrations. In the absence of gas analyzers, the head of the facility must establish the procedure for sampling and control of samples.
531. If gas leaks from cylinders are detected, they must be removed from the warehouse to a safe place.
532. Persons in shoes lined with metal nails or horseshoes are not allowed in the warehouse where gas cylinders are stored.
533. Cylinders with GG, having shoes, must be stored in a vertical position in special nests, cages or other devices that prevent them from falling.
Cylinders that do not have shoes must be stored in a horizontal position on frames or racks. The height of the stack in this case should not exceed 1.5 m, and the valves should be closed with safety caps and turned in one direction.
534. Storage of any other substances, materials and equipment in gas warehouses is not allowed.
535. Premises of warehouses with GG should be provided with natural ventilation.
536. Storage of a stock of roughage is permitted only in outbuildings (buildings) separated from farm buildings by solid non-combustible walls (partitions) and ceilings with a fire resistance limit of at least 0.75 hours.
Extensions (built-ins) should have exits only directly to the outside.
537. Stacks (stacks), sheds and stacks of roughage must be located at a distance of at least 15 m from power lines, at least 20 m from roads and at least 50 m from buildings and structures.
538. Areas for placing stacks (stacks), as well as a pair of stacks (stacks) or stacks, must be plowed around the perimeter with a strip at least 4 m wide. The distance from the edge of the strip to the stack (stack) located on the site must be at least 15 m , and to a free-standing stack (stack) - at least 5 m.
The area of the base of one stack (stack) should not exceed 150 m2, and the pile of pressed hay (straw) - 500 m2.
Fire-prevention distances between individual stacks, sheds and stacks (stacks) must be at least 20 m. m.
Fire distances between quarters (20 stacks or stacks are allowed per quarter) must be at least 100 m.
539. In stacks (stacks) and stacks of hay with high humidity it is necessary to organize temperature control.
540. Tractors and vehicles working in roughage warehouses must be equipped with spark arresters.
Tractor-tractors during unloading operations should not drive up to stacks at a distance of less than 3 m.
541. Before the start of harvesting, granaries and grain dryers should be checked for suitability for use; detected faults must be eliminated before the start of drying and receiving grain.
Grain warehouses should be placed in separate buildings. The gates in them should open outward and not be cluttered.
542. When grain is stored in bulk, the distance from the top of the embankment to combustible coating structures, as well as to lamps and electrical wires, must be at least 0.5 m.
In places where grain is transported through openings in fire barriers, protective devices must be installed.
store other materials and equipment together with grain;
to use grain cleaning and other machines with internal combustion engines inside warehouses;
work on mobile mechanisms with closed gates on both sides of the warehouse;
ignition of dryers operating on solid fuels with the help of flammable and combustible liquids, and those operating on liquid fuels - with the help of torches;
work on dryers with faulty temperature control devices and automatic shutdown of the fuel supply when the torch in the furnace is attenuated, with or without an electric ignition system;
fill the grain above the level of the conveyor belt and allow the belt to rub against the conveyor structure.
544. Control over the temperature of the grain when the dryer is running must be carried out by sampling at least every 2 hours.
Cleaning of the loading and unloading mechanisms of the dryer from dust and grain should be carried out after a day of its operation.
545. A mobile drying unit must be installed at a distance of at least 10 m from the granary building.
The design of dryer furnaces must exclude sparks. Chimneys should be equipped with spark arresters, and in places where they pass through combustible structures, fire-prevention cuts should be arranged.
546. When ventilating grain in granaries, fans should be installed at a distance of at least 2.5 m from combustible walls. Air ducts must be made of non-combustible materials.
547. Timber warehouses with a capacity of more than 10 thousand m3 must comply with the requirements of the design standards for timber warehouses. In timber warehouses with a capacity of less than 10 thousand m3, plans for the placement of stacks should be developed and agreed with the state fire supervision authorities, indicating the maximum volume of stored materials, fire distances and passages between the stacks, as well as between the stacks and neighboring objects.
548. Storage of timber, equipment, etc. is not allowed in fire breaks between stacks.
549. Places allotted for stacks must be cleared to the ground of grass cover, combustible debris and waste or covered with a layer of sand, earth or gravel at least 15 cm thick.
550. For each warehouse, an operational fire extinguishing plan should be developed with the definition of measures for dismantling stacks, heaps of pulpwood, wood chips, etc., taking into account the possibility of attracting employees and equipment of the enterprise. Every year, before the start of the spring-summer fire hazard period, the plan must be worked out with the involvement of employees from all shifts of the enterprise and the relevant fire departments.
551. In addition to primary fire extinguishing equipment, warehouses should be equipped with points (posts) with a stock of various types of fire equipment in quantities determined by operational fire extinguishing plans.
552. It is not allowed to carry out work in the warehouse that is not related to the storage of timber.
553. Premises for heating workers in timber warehouses can only be arranged in separate buildings in compliance with fire safety distances in agreement with the state fire supervision authorities.
For heating these rooms, it is allowed to use only factory-made electric heaters.
554. Winches with internal combustion engines should be placed at a distance of at least 15 m from stacks of roundwood.
The area around the winch must be free from lumps, bark and other combustible waste and debris. Fuels and lubricants for refueling engines may be stored in an amount of not more than one barrel and at a distance of at least 10 m from the winch and 20 m from the nearest stack.
555. When stacking and dismantling lumber stacks, transport packages must be installed only on one side of the passage, while the width of the remaining carriageway must be at least 4 m. The total volume of lumber not stacked in stacks should not exceed their daily receipt at the warehouse.
GOST 25328-82
Group G12
INTERSTATE STANDARD
CEMENT FOR MORTAR
Specifications
masonry cement. Specifications
ISS 91.100.10
OKP 57 3811
Introduction date 1983-01-01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of Industry of Building Materials of the USSR
2. APPROVED AND INTRODUCED BY Decree of the State Committee of the USSR for Construction Affairs of 09.04.82 N 93
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS
Item number |
|
2.1, 4.1, 6.1 |
5. REPUBLICATION. December 2003
This standard applies to cement obtained on the basis of Portland cement clinker and intended for mortars used in the production of masonry, facing and plastering works, as well as for the manufacture of unreinforced concrete grades M 50 and below, for which there are no requirements for frost resistance.
1. TECHNICAL REQUIREMENTS
1. TECHNICAL REQUIREMENTS
1.1. Cement must be produced in accordance with the requirements of this standard according to technological regulations approved in the prescribed manner.
1.2. Cement for the construction of mortars is a product obtained by joint grinding of Portland cement clinker, gypsum, active mineral additives and filler additives.
1.3. The materials used for the manufacture of cement must comply with the requirements stipulated in the standards or specifications for these materials.
1.4. Additives
1.4.1. Active mineral additives - according to normative and technical documentation (NTD).
Granulated blast-furnace or electrothermophosphoric slags - according to GOST 3476.
1.4.2. Filler additives
Quartz sand with a silica content of at least 90%. The content of clay, silt and fine pulverized fractions of less than 0.05 mm should not be more than 3%.
Crystalline limestone, marble and dust from electrostatic precipitators of clinker kilns - according to NTD.
1.5. Gypsum stone - according to GOST 4013. It is allowed to use phospho- and borogypsum according to NTD.
1.7. It is allowed to introduce plasticizing or water-repellent additives into cement that improve the quality of cement. The amount of plasticizing additives should be no more than 0.5%, and water-repellent additives - no more than 0.3% of the mass of cement.
1.8. It is allowed to introduce air-entraining additives into cement in an amount of up to 1% of the mass of cement.
1.9. In the manufacture of cement, in order to intensify the grinding process, it is allowed to introduce technological additives that do not impair the quality of cement, in an amount of not more than 1% of the mass of cement.
1.10. The compressive strength of cement at 28 days of age must be at least 19.6 MPa (200 kgf/cm).
1.11. The beginning of cement setting should occur no earlier than 45 minutes, and the end - no later than 12 hours from the start of mixing.
1.12. The water separation of the cement paste made at W/C=1.0 should not be more than 30% by volume.
1.13. Cement samples shall show uniform volume change when tested by boiling in water.
1.14. The fineness of cement grinding should be such that when sifted through a sieve N 008 according to GOST 6613, at least 88% of the mass of the sieved sample passes.
1.15. The content of sulfuric anhydride in cement must be at least 1.5 and not more than 3.5% of the mass of cement.
2. ACCEPTANCE RULES
2.1. Cement acceptance rules - according to GOST 30515.
3. TEST METHODS
3.1. The chemical composition of cement is determined according to GOST 5382.
3.2. The physical and mechanical properties of cement are determined according to GOST 310.1 - GOST 310.6.
3.4. The water separation of cement is determined by the following method.
3.4.1. Equipment
Porcelain glass with a capacity of 1 l.
Metal spatula.
Technical scales.
Graduated cylinder with a capacity of 500 ml.
3.4.2. Testing
350 g of cement and 350 g of water are weighed with an accuracy of 1 g. Water is poured into a porcelain glass, then a sample of cement is poured into the glass for 1 min, continuously stirring the contents with a metal spatula. The resulting cement paste is stirred for another 4 minutes and carefully poured into a graduated cylinder. The cylinder with the cement paste is placed on the table and the volume of the cement paste is immediately counted. During the experiment, the cylinder must stand still and not be subjected to shocks and shaking.
The volume of settled cement paste is noted 4 hours after the first reading.
The coefficient of water separation (volume) as a percentage is calculated by the formula
where is the initial volume of cement paste, cm;
- the volume of settled cement paste, see
4. PACKAGING, LABELING, TRANSPORT AND STORAGE
4.1. Packaging, marking, transportation and storage of cement is carried out in accordance with GOST 30515.
5. INSTRUCTIONS FOR USE
5.1. Cement must be used in accordance with the Instructions for the preparation and use of mortars approved by Gosstroy.
Due to the delayed hardening at low temperatures, this cement should generally be used at an ambient temperature of at least 10 °C.
6. MANUFACTURER WARRANTY
6.1. The manufacturer guarantees the compliance of cement with all the requirements of this standard within a month, subject to compliance with its transportation and in accordance with the requirements of GOST 30515.
Electronic text of the document
prepared by CJSC "Kodeks" and checked against:
official publication
Moscow: IPK Standards Publishing House, 2004
When laying cable lines directly in the ground, the cables must be laid in trenches and have backfilling from below, and backfilling from above with a layer of fine earth that does not contain stones, construction debris and slag.
Cables throughout their entire length must be protected from mechanical damage by coating at a voltage of 35 kV and above with reinforced concrete slabs with a thickness of at least 50 mm; at voltages below 35 kV - with slabs or ordinary clay bricks in one layer across the cable route; when digging a trench with an earthmoving mechanism with a cutter width of less than 250 mm, as well as for one cable - along the cable line route. The use of silicate, as well as clay hollow or perforated bricks is not allowed.
When laying at a depth of 1-1.2 m, cables of 20 kV and below (except for city power cables) may not be protected from mechanical damage.
Cables up to 1 kV should have such protection only in areas where mechanical damage is likely (for example, in places of frequent excavation). Asphalt pavements of streets, etc. are regarded as places where excavation is carried out in rare cases. For cable lines up to 20 kV, except for lines above 1 kV, supplying electrical receivers of category I *, it is allowed to use signal plastic tapes instead of bricks in trenches with no more than two cable lines that meet the technical requirements approved by the USSR Ministry of Energy. It is not allowed to use signal tapes at the intersections of cable lines with utilities and above cable boxes at a distance of 2 m in each direction from the crossed communication or box, as well as at the approaches of lines to switchgears and substations within a radius of 5 m.
* According to local conditions, with the consent of the owner of the lines, it is allowed to expand the scope of signal tapes.
The signal tape should be laid in a trench above the cables at a distance of 250 mm from their outer covers. When one cable is located in a trench, the tape should be laid along the axis of the cable, with a larger number of cables, the edges of the tape should protrude beyond the outermost cables by at least 50 mm. When laying more than one tape across the width of the trench, adjacent tapes must be laid with an overlap of at least 50 mm wide.
When using a signal tape, laying cables in a trench with a cable cushion device, sprinkling the cables with the first layer of earth and laying the tape, including sprinkling the tape with a layer of earth along the entire length, must be carried out in the presence of a representative of the electrical installation organization and the owner of the power grid.
2.3.84
The depth of cable lines from the planning mark should be at least: lines up to 20 kV 0.7 m; 35 kV 1 m; at the intersection of streets and squares, regardless of voltage 1 m.
Cable oil-filled lines 110-220 kV must have a laying depth from the planning mark of at least 1.5 m.
It is allowed to reduce the depth to 0.5 m in sections up to 5 m long when lines are introduced into buildings, as well as at their intersections with underground structures, provided that the cables are protected from mechanical damage (for example, laying in pipes).
The laying of 6-10 kV cable lines on arable land should be carried out at a depth of at least 1 m, while the strip of land above the route can be occupied by crops.
2.3.85
The clear distance from the cable laid directly in the ground to the foundations of buildings and structures must be at least 0.6 m. Laying cables directly in the ground under the foundations of buildings and structures is not allowed. When laying transit cables in the basements and technical undergrounds of residential and public buildings, one should be guided by the SNiP of the Gosstroy of Russia.
2.3.86
With parallel laying of cable lines, the horizontal distance in the light between the cables must be at least:
1) 100 mm between power cables up to 10 kV, as well as between them and control cables;
2) 250 mm between 20-35 kV cables and between them and other cables;
3) 500 mm* between cables operated by different organizations, as well as between power cables and communication cables;
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4) 500 mm between 110-220 kV oil-filled cables and other cables; at the same time, low-pressure oil-filled cable lines are separated from one another and from other cables by reinforced concrete slabs placed on edge; in addition, the electromagnetic influence on communication cables should be calculated.
It is allowed, if necessary, by agreement between operating organizations, taking into account local conditions, reducing the distances specified in clauses 2 and 3 to 100 mm, and between power cables up to 10 kV and communication cables, except for cables with circuits sealed by high-frequency telephone communication systems, up to 250 mm, provided that the cables are protected from damage that may occur during a short circuit in one of the cables (laying in pipes, installing fireproof partitions, etc.).
The distance between the control cables is not standardized.
2.3.87
When laying cable lines in the plantation zone, the distance from the cables to the tree trunks should, as a rule, be at least 2 m. It is allowed, in agreement with the organization in charge of the green spaces, to reduce this distance, provided that the cables are laid in pipes laid by digging .
When laying cables within the green zone with shrub plantings, the indicated distances can be reduced to 0.75 m.
2.3.88
With parallel laying, the horizontal distance in the light from cable lines with voltage up to 35 kV and oil-filled cable lines to pipelines, water supply, sewerage and drainage must be at least 1 m; to gas pipelines of low (0.0049 MPa), medium (0.294 MPa) and high pressure (more than 0.294 to 0.588 MPa) - at least 1 m; to high pressure gas pipelines (more than 0.588 to 1.176 MPa) - at least 2 m; to heat pipelines - see 2.3.89.
In cramped conditions, it is allowed to reduce the specified distances for cable lines to 35 kV, with the exception of distances to pipelines with flammable liquids and gases, up to 0.5 m without special cable protection and up to 0.25 m when laying cables in pipes. For oil-filled cable lines 110-220 kV in the approach section no longer than 50 m, it is allowed to reduce the horizontal distance in the light to pipelines, with the exception of pipelines with flammable liquids and gases, to 0.5 m, provided that a protective wall is installed between the oil-filled cables and the pipeline excluding the possibility of mechanical damage. Parallel laying of cables above and below pipelines is not allowed.
2.3.89
When laying a cable line in parallel with a heat pipeline, the clear distance between the cable and the wall of the heat pipeline channel must be at least 2 m, or the heat pipeline in the entire area of approach to the cable line must have such thermal insulation that additional heating of the earth by the heat pipeline at the place where the cables pass at any time of the year is not exceeded 10°C for cable lines up to 10 kV and 5°C - for lines 20-220 kV.
2.3.90
When laying a cable line in parallel with railways, cables should be laid, as a rule, outside the exclusion zone of the road. Laying cables within the exclusion zone is allowed only upon agreement with the organizations of the Ministry of Railways, while the distance from the cable to the axis of the railway track must be at least 3.25 m, and for an electrified road - at least 10.75 m. In cramped conditions it is allowed to reduce the specified distances, while the cables in the entire approach section must be laid in blocks or pipes.
For electrified roads on direct current, blocks or pipes must be insulating (asbestos-cement, impregnated with tar or bitumen, etc.) *.
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2.3.91
When laying a cable line in parallel with tram tracks, the distance from the cable to the axis of the tram track must be at least 2.75 m. 2.3.90.
2.3.92
When laying a cable line in parallel with motor roads of categories I and II (see 2.5.145), cables must be laid on the outside of the ditch or the bottom of the embankment at a distance of at least 1 m from the edge or at least 1.5 m from the curb stone. Reducing the specified distance is allowed in each individual case in agreement with the relevant road administrations.
2.3.93
When laying a cable line in parallel with an overhead line of 110 kV and above, the distance from the cable to the vertical plane passing through the outermost wire of the line must be at least 10 m.
The clear distance from the cable line to grounded parts and ground electrodes of overhead lines above 1 kV must be at least 5 m at voltages up to 35 kV, 10 m at voltages of 110 kV and above. In cramped conditions, the distance from cable lines to underground parts and ground electrodes of individual overhead lines above 1 kV is allowed at least 2 m; at the same time, the distance from the cable to the vertical plane passing through the overhead line wire is not standardized.
The clear distance from the cable line to the overhead line support up to 1 kV must be at least 1 m, and when laying the cable in the approach area in an insulating pipe, 0.5 m.
In the territories of power plants and substations in cramped conditions, it is allowed to lay cable lines at distances of at least 0.5 m from the underground part of overhead communication towers (current conductors) and overhead lines above 1 kV, if the grounding devices of these towers are connected to the substation ground loop.
2.3.94
*. When cable lines cross other cables, they must be separated by a layer of earth with a thickness of at least 0.5 m; this distance in cramped conditions for cables up to 35 kV can be reduced to 0.15 m, provided that the cables are separated along the entire intersection plus 1 m in each direction by slabs or pipes made of concrete or other equal strength material; the communication cables must be located above the power cables.
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* Agreed with the Ministry of Communications of the USSR.
2.3.95
When cable lines cross pipelines, including oil and gas pipelines, the distance between the cables and the pipeline must be at least 0.5 m. It is allowed to reduce this distance to 0.25 m, provided that the cable is laid at the intersection plus at least 2 m in each direction in pipes.
When crossing a cable oil-filled line of pipelines, the clear distance between them must be at least 1 m. For cramped conditions, it is allowed to take a distance of at least 0.25 m, but provided that the cables are placed in pipes or reinforced concrete trays with a lid.
2.3.96
When crossing cable lines up to 35 kV heat pipelines, the distance between the cables and the overlap of the heat pipeline in the light must be at least 0.5 m, and in cramped conditions - at least 0.25 m. In this case, the heat pipeline at the intersection plus 2 m in each direction from the outermost cables must have such thermal insulation that the temperature of the earth does not rise by more than 10 ° C in relation to the highest summer temperature and by 15 ° C in relation to the lowest winter temperature.
In cases where the specified conditions cannot be met, one of the following measures is allowed: deepening of cables to 0.5 m instead of 0.7 m (see 2.3.84); use of a cable insert of a larger cross section; laying cables under the heat pipeline in pipes at a distance of at least 0.5 m from it, while the pipes must be laid in such a way that the cables can be replaced without excavation (for example, inserting pipe ends into chambers).
When crossing a cable oil-filled line of a heat pipe, the distance between the cables and the overlap of the heat pipe must be at least 1 m, and in cramped conditions - at least 0.5 m. thermal insulation so that the temperature of the earth does not rise by more than 5 ° C at any time of the year.
2.3.97
When cable lines cross railways and roads, cables must be laid in tunnels, blocks or pipes across the entire width of the exclusion zone at a depth of at least 1 m from the roadbed and at least 0.5 m from the bottom of drainage ditches. In the absence of an exclusion zone, the specified laying conditions must be met only at the intersection plus 2 m on both sides of the roadbed.
When cable lines cross electrified and subject to direct current electrification * railways, blocks and pipes must be insulating (see 2.3.90). The crossing point must be at least 10 m away from switches, crosses and places where suction cables are attached to the rails. The crossing of cables with the tracks of electrified rail transport should be carried out at an angle of 75-90 ° to the axis of the track.
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* Agreed with the Ministry of Railways.
The ends of the blocks and pipes must be sunk with jute braided cords coated with waterproof (crumpled) clay to a depth of at least 300 mm.
When crossing dead-end industrial roads with low traffic intensity, as well as special routes (for example, on slipways, etc.), cables, as a rule, should be laid directly in the ground.
When crossing the route of cable lines by a newly constructed non-electrified railway or a motor road, it is not required to re-lay existing cable lines. At the intersection, reserve blocks or pipes with tightly sealed ends should be laid in the event of repair of cables in the required number.
In the event of a cable line transitioning into an overhead cable, it must come out to the surface at a distance of at least 3.5 m from the bottom of the embankment or from the edge of the canvas.
2.3.98
When cable lines cross tram tracks, cables must be laid in insulating blocks or pipes (see 2.3.90). The crossing must be carried out at a distance of at least 3 m from the switches, crosses and places where suction cables are attached to the rails.
2.3.99
When cable lines cross entrances for vehicles to yards, garages, etc., cables should be laid in pipes. In the same way, cables must be protected at the intersection of streams and ditches.
2.3.100
When installing cable boxes on cable lines, the clear distance between the cable box body and the nearest cable must be at least 250 mm.
When laying cable lines on steep routes, the installation of cable boxes on them is not recommended. If it is necessary to install cable boxes in such sections, horizontal platforms must be made under them.
To ensure the possibility of remounting the couplings in case of their damage on the cable line, it is required to lay the cable on both sides of the couplings with a margin.
2.3.101
If there are stray currents of dangerous values along the cable line route, it is necessary:
1. Change the route of the cable line in order to avoid dangerous areas.
2. If it is impossible to change the route: provide for measures to minimize the levels of stray currents; use cables with increased resistance to corrosion; to carry out active protection of cables from the effects of electrocorrosion.
When laying cables in aggressive soils and areas with the presence of stray currents of unacceptable values, cathodic polarization should be used (installation of electrical drains, protectors, cathodic protection). For any method of connecting electrical drainage devices, the norms of potential differences in the suction sections provided for #M12291 871001027SNiP 3.04.03-85 #S "Protection of building structures and structures against corrosion" Gosstroy of Russia. It is not recommended to use cathodic protection with external current on cables laid in saline soils or saline water bodies.
The need to protect cable lines from corrosion should be determined by the combined data of electrical measurements and chemical analyzes of soil samples. Corrosion protection of cable lines should not create conditions dangerous for the operation of adjacent underground structures. The designed corrosion protection measures must be implemented before the new cable line is put into operation. In the presence of stray currents in the ground, it is necessary to install control points on cable lines in places and at distances that allow determining the boundaries of dangerous zones, which is necessary for the subsequent rational selection and placement of protective equipment.
To control potentials on cable lines, it is allowed to use the places where cables exit to transformer substations, distribution points, etc.