TYPICAL TECHNOLOGICAL CARD (TTK)

TEST FOR STRENGTH AND TIGHTNESS OF OUTDOOR HEAT NETWORKS

I. SCOPE

I. SCOPE

1.1. A typical technological map (hereinafter referred to as TTK) is a comprehensive organizational and technological document developed on the basis of methods scientific organization labor to perform the technological process and determining the composition of production operations using the most modern means of mechanization and methods for performing work according to a specific technology. TTK is intended for use in the development of the Project for the Production of Works (PPR) by construction departments and is its integral part in accordance with MDS 12-81.2007.

1.2. This TTC provides instructions on the organization and technology of work on testing the strength and tightness of outdoor heating networks, determines the composition of production operations, requirements for quality control and acceptance of work, planned labor intensity of work, labor, production and material resources, measures for industrial safety and labor protection.

1.3. The regulatory framework for the development of technological maps are:

- standard drawings;

- building codes and regulations (SNiP, SN, SP);

- factory instructions and specifications (TU);

- norms and prices for construction and installation works (GESN-2001 ENiR);

- production norms for the consumption of materials (NPRM);

- local progressive norms and prices, labor costs norms, material and technical resources consumption norms.

1.4. The purpose of creating the TC is to describe solutions for the organization and technology of work on testing the strength and tightness of external heating networks in order to ensure their High Quality, and:

- cost reduction of works;

- reduction of construction time;

- ensuring the safety of work performed;

- organization of rhythmic work;

- rational use labor resources and machines;

- unification of technological solutions.

1.5. Work technological maps(RTC) for execution certain types work on testing the strength and tightness of outdoor heating networks.

The design features of their implementation are decided in each case by the Working Design. The composition and level of detail of materials developed in the RTK are established by the relevant contracting construction organization, based on the specifics and scope of work performed.

RTK are considered and approved as part of the PPR by the head of the General Contractor Construction Organization.

1.6. TTK can be tied to a specific object and construction conditions. This process consists in clarifying the scope of work, means of mechanization, the need for labor and material and technical resources.

The procedure for linking the TTK to local conditions:

- consideration of map materials and selection of the desired option;

- verification of the compliance of the initial data (volumes of work, time standards, brands and types of mechanisms, building materials used, composition of the worker link) to the accepted option;

- adjustment of the scope of work in accordance with the chosen option for the production of work and a specific design solution;

- recalculation of costing, technical and economic indicators, the need for machines, mechanisms, tools and material and technical resources in relation to the chosen option;

- design of the graphic part with a specific binding of mechanisms, equipment and fixtures in accordance with their actual dimensions.

1.7. A typical flow chart has been developed for engineering and technical workers (foremen, foremen, foremen) and workers performing work in the III temperature zone, in order to familiarize (train) them with the rules for performing work on testing the strength and tightness of outdoor heating networks with using the most modern means of mechanization, progressive designs and materials, methods of performing work.

The technological map has been developed for the following scopes of work:

II. GENERAL PROVISIONS

2.1. The technological map has been developed for a set of works on testing the strength and tightness of outdoor heating networks.

2.2. Works on testing the strength and tightness of outdoor heating networks are carried out in one shift, the working hours during the shift are:

2.3. The scope of work performed during strength and tightness testing of external heating networks includes:

- preparation of the working whip for preliminary testing;

- binding of filling and pressure testing units and testing them;

- filling with water the section of the pipeline to be tested;

- rise in pressure to test pressure;

- testing the working whip for strength;

- checking the working whip for tightness;

- switching of stop valves;

- control of water pressure and temperature;

- final (acceptance) testing of the pipeline.

2.4. The technological map provides for the performance of work by an integrated mechanized unit consisting of: self-priming centrifugal pump S-245 "Andijan" designed for pumping water capacity 100 m/h, self-priming height h=5.0 m, diesel engine power T-62-1 N=13 hp, overall dimensions 1800x930x1225 mm, weight P=800 kg, diameter of suction and pressure hoses 100 mm; mobile diesel compressor Atlas Copco XAS 97 (P=7 bar productivity 5.3 m/min).

Fig.1. Self-priming pump S-245

Fig.2. Compressor Atlas Copco XAS 97

2.5. For testing the strength and tightness of outdoor heating networks, the following materials are used as the main materials: steel pipes with bitumen perlite insulation up to 426 mm in diameter according to GOST 3262-75 *); coated electrodes metal for manual arc welding type E42 meeting the requirements of GOST 9467-75 *.

2.6. Work on preliminary testing for strength and tightness of external heating networks should be carried out in accordance with the requirements of the following regulatory documents:

- SP 48.13330.2011. "SNiP 12-01-2004 Organization of construction. Updated edition";

- SNiP 41-02-2003 Heating networks;

- SNiP 41-03-2003. Thermal insulation of equipment and pipelines;

- SNiP 3.05.03-85. Heating network;

- STO NOSTROY 2.33.14-2011. Organization construction industry. General provisions;

- STO NOSTROY 2.33.51-2011. Organization of construction production. Preparation and production of construction and installation works;

- SNiP 12-03-2001. Labor safety in construction. Part 1. General requirements;

- SNiP 12-04-2002. Labor safety in construction. Part 2. Construction production;

- RD 11-02-2006. Requirements for the composition and procedure for maintaining executive documentation during construction, reconstruction, overhaul capital construction facilities and requirements for certificates of survey of works, structures, sections of engineering and technical support networks;

- RD 11-05-2007. The procedure for maintaining a general and (or) special journal for recording the performance of work during construction, reconstruction, overhaul of capital construction projects.

III. ORGANIZATION AND TECHNOLOGY OF WORK PERFORMANCE

3.1. In accordance with SP 48.13330.2001 "Organization of construction", prior to the commencement of construction and installation works at the facility, the Contractor is obliged to in due course obtain from the Customer project documentation and permission to perform construction and installation works. Work without permission is prohibited.

3.2. Prior to the start of work on a preliminary test for the strength and tightness of external heating networks, it is necessary to carry out a set of organizational and technical measures, including:

- develop RTK or PPR for testing heat networks;

- appoint persons responsible for the safe performance of work, as well as their control and quality of performance;

- briefing the members of the safety team;

- establish temporary inventory household premises for the storage of building materials, tools, inventory, heating workers, eating, drying and storing work clothes, bathrooms, etc.;

- provide the site with working documentation approved for the production of work;

- prepare machines, mechanisms and equipment for the production of work and deliver them to the facility;

- provide workers with manual machines, tools and personal protective equipment;

- provide the construction site with fire-fighting equipment and signaling equipment;

- prepare places for storing building materials, products and structures;

- fence the construction site and put up warning signs illuminated at night;

- provide communication for operational and dispatching control of the production of works;

- deliver to the work area necessary materials, fixtures, inventory, tools and means for the safe production of work;

- to test construction machines, means of mechanization of work and equipment according to the nomenclature provided for by the RTK or PPR;

- draw up an act of readiness of the object for the production of work;

- obtain permission from the technical supervision of the Customer to start work (clause 4.1.3.2 of RD 08-296-99).

3.4. General instructions

3.4.1. Hydraulic tests

3.4.1.1. Hydraulic testing of pipelines should be carried out in compliance with the following basic requirements:

- test pressure must be provided at the top point (mark) of the pipelines;

- the water temperature during testing should not be lower than 5°С;

- at a negative outside temperature, the pipeline must be filled with water at a temperature not exceeding 70 ° C and it must be possible to fill and empty it within 1 hour;

- when gradually filling with water, air must be completely removed from the pipelines through air vent valves;

- a test pressure equal to the working pressure is set in the pipeline and maintained for the time necessary to inspect the joints, but not less than 10 minutes and then reduced to the working one;

- at operating pressure, the pipeline must be inspected along its entire length;

- if no defects or leaks are found during the trial pressure test, it is brought to the test pressure (1.25P) and maintained for the time necessary for a thorough inspection, but not less than 10 minutes.

3.4.1.2. The results of hydraulic tests of the pipeline for strength and tightness are considered satisfactory if during their implementation:

- there was no pressure drop;

- no signs of rupture, leakage or fogging were found in the welds, as well as leaks in the base metal, flange joints, fittings and other elements of pipelines;

- there are no signs of shift or deformation of the pipeline and fixed supports.

3.4.1.3. Pipeline defects should be eliminated after the pressure is reduced to atmospheric.

3.4.1.4. The technology for correcting defects and the control procedure should be defined in the Working Flow Chart.

3.4.2. Pneumatic tests

3.4.2.1. Pneumatic tests should be carried out for steel pipelines with a working pressure of not more than 1.6 MPa (16 kgf / cm) and a temperature of up to 250 ° C, mounted from pipes and parts tested for strength and tightness (density) by manufacturers in accordance with GOST 3845-75 * (at the same time, the factory test pressure for pipes, fittings and other products and parts of pipelines must be 20% higher than the test pressure adopted for the installed pipeline).

3.4.2.2. The installation of cast iron fittings (except for ductile iron valves) is not allowed for the duration of the test.

3.4.2.3. The pneumatic test is carried out in the following sequence:

- clean and purge the pipeline;

- install plugs and pressure gauges;

- connect the compressor to the pipeline;

- smoothly fill the pipeline with air at a speed of not more than 0.3 MPa (3 kgf/cm) in 1 hour;

- at a pressure value equal to 0.3 test, but not more than 0.3 MPa (3 kgf / cm), visually inspect the route [the entrance to the security (dangerous) zone, but without descending into the trench]. For the period of inspection of the route, the pressure increase must be stopped;

- when the test pressure is reached, the pipeline is held to equalize the temperature along the length of the pipeline;

- after leveling the air temperature, the test pressure is maintained for 30 minutes - the actual test;

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Hydraulic testing of pipelines.

Hydraulic testing of heating networks is carried out twice: first, they check the strength and density of the heat pipeline without equipment and fittings, then the entire heat pipeline, which is ready for operation, with installed mud collectors, valves, compensators and other equipment. A re-check is necessary because it is more difficult to check the density and strength of welds when the equipment and fittings are installed.

In cases where, when testing heat pipelines without equipment and fittings, there is a pressure drop across the instruments, then the available welds loose (naturally, if there are no fistulas, cracks, etc. in the pipes themselves). The pressure drop during testing of pipelines with installed equipment and valves may indicate that, in addition to joints, gland seals or flange connections are also defective.

During the preliminary test, not only welds, but also the walls of pipelines are checked for density and strength. it happens that the pipes have cracks, fistulas and other factory defects. Tests of the installed pipeline must be carried out before the installation of thermal insulation. In addition, the pipeline should not be backfilled or closed by engineering structures. When the pipeline is welded from seamless seamless pipes, it may be submitted for testing already insulated, but only with open welded joints.

During the final test, the junction points of individual sections (in cases of testing the heat pipe in parts), welded seams of mud collectors and stuffing box compensators, equipment cases, flange connections are subject to verification. During the test, the glands must be sealed and the sectional valves fully open.

The need for two tests of heating mains is also caused by the fact that in long sections it is not possible to check the entire heat pipeline at a time. It would take a long time to leave the trench open. In this regard, individual sections of heating networks are tested before backfilling, as they are prepared. The length of the test section depends on the timing of construction on individual sections of the route, on the availability of manual, hydraulic or mechanized presses, filling units, piston pumps, the power of the water source (river, pond, lake, water supply), working conditions, terrain, etc. .

During hydraulic testing of heating networks, the sequence of work is as follows:
- carry out cleaning of heat pipelines;
- install pressure gauges, plugs and taps;
- connect water and hydraulic press;
- fill the pipelines with water to the required pressure;
- conduct an inspection of heat pipelines and mark the places where defects are found;
- eliminate defects;
- make a second test;
- disconnect from the water supply and drain the water from the pipes;
- remove gauges and plugs.

To fill the pipelines with water and to remove air from the pipes, the water supply is connected to the lower part of the heat pipe. Near each air crane it is necessary to put a duty officer. First, only air enters through the air vents, then the air-water mixture and, finally, only water. When the outlet is only water, the valve is closed. Then the tap is periodically opened two or three more times to completely release the remaining part of the air from the upper points. Before filling the heating network, all air vents must be opened and drains closed.

The test is carried out with a pressure equal to the working pressure with a factor of 1.25. Under the working understand the maximum pressure that can occur in this area during operation.

In cases of testing a heat pipeline without equipment and fittings, the pressure is raised to the calculated one and maintained for 10 minutes, while controlling the pressure drop, after which it is reduced to the working one, an inspection is carried out welded joints and tap the joints. The tests are considered satisfactory if there is no pressure drop, no leakage and no sweating of the joints.

Tests with installed equipment and fittings are carried out with a holding time of 15 minutes, flange and welded joints, fittings and equipment, gland seals are inspected, after which the pressure is reduced to working pressure. The tests are considered satisfactory if the pressure drop does not exceed 10% within 2 hours. The test pressure checks not only the tightness, but also the strength of the equipment and pipeline.

After the test, the water must be completely removed from the pipes. As a rule, the test water is not specially prepared and can reduce the quality of the network water and cause corrosion of the internal surfaces of the pipes.

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Hydraulic tests are carried out in accordance with SNiP. After their completion, an act is drawn up indicating the operability of the system.

They are performed at different stages of communication operation. The scan parameters are calculated for each system separately, depending on its type.

Article content

Why and when to carry out hydraulic tests?

Hydraulic testing is a type non-destructive testing, which is carried out to check the strength and density of pipeline systems. All operating equipment is exposed to them at different stages of operation.

In general, there are three cases in which testing must be mandatory regardless of the purpose of the pipeline:

• after finishing production process for the production of equipment or parts of the pipeline system;
• after completion of the installation work of the pipeline;
• during the operation of the equipment.

Hydraulic testing is an important procedure that confirms or refutes the reliability of a pressure system in operation. This is necessary to prevent accidents on highways and preserve the health of citizens.

A procedure is being carried out for hydraulic testing of pipelines in extreme conditions. The pressure under which it passes is called test pressure. It exceeds the usual working pressure by 1.25-1.5 times.

Features of hydraulic tests

Test pressure is supplied to the pipeline system smoothly and slowly so as not to provoke water hammer and the formation of accidents. The pressure value is determined not by eye, but by a special formula, but in practice, as a rule, it is 25% more than the working pressure.

The force of water supply is controlled on pressure gauges and measurement channels. According to SNiP, jumps in indicators are allowed, since it is possible to quickly measure the temperature of the liquid in the pipeline vessel. When filling it, it is imperative to monitor the accumulation of gas in different parts of the system.

This possibility should be ruled out at an early stage.

After filling the pipeline, the so-called holding time begins - a period during which the equipment under test is under increased pressure. It is important to ensure that it is at the same level during exposure. After its completion, the pressure is minimized to a working state.

While the test is being carried out, no one should be near the pipeline.

Personnel serving it must wait in a safe place, as checking the operation of the system can be explosive. After the end of the process, the results obtained are evaluated according to SNiP. The pipeline is inspected for metal explosions, deformations.

Hydraulic test parameters

When conducting a pipeline quality check, it is necessary to determine the indicators of the following work parameters:

1. Pressure.
2. Temperatures.
3. Holding time.

The lower limit of the test pressure is calculated using the following formula: Ph = KhP. The upper limit should not exceed the sum of the total membrane and bending stresses, which will reach 1.7 [δ]Th. The formula is deciphered as follows:

• Р is the design pressure, the parameters of which are provided by the manufacturer, or the working pressure, if the tests are carried out after installation;
• [δ]Th is the rated voltage that is allowed at the test temperature Th;
• [δ]T is the allowable stress at design temperature T;
• Kh is a conditional coefficient that takes on a different value for different objects. When checking pipelines, it is equal to 1.25.

The water temperature should not fall below 5°C and rise above 40°C. The only exceptions are those cases where the temperature of the hydraulic component is indicated in specifications object under study. Be that as it may, the air temperature during the test should not fall below the same 5 ° C.

The holding time must be specified in project documentation to the object. It should not be less than 5 minutes. If exact parameters are not provided, then the holding time is calculated based on the thickness of the walls of the pipeline. For example, with a thickness of up to 50 mm, the pressure test lasts at least 10 minutes, with a thickness of more than 100 mm - at least 30 minutes.

Testing of fire hydrants and water mains

A hydrant is equipment responsible for the rapid elimination of fire ignitions, so it must always be in working order. the main task fire hydrants - to provide the optimal amount of water to fight a fire at its initial stage.

Pressure pipelines are checked in accordance with SNiP B III-3-81.

Pipes made of cast iron and asbestos are tested with a pipeline length of not more than 1 km at a time. Polyethylene water pipelines are checked in sections of 0.5 km. All other water supply systems are checked in segments of no more than 1 km. The holding time for water supply pipes made of metal and should be at least 10 m, for polyethylene - at least 30 m.

Heating system testing

Checking of thermal networks is carried out immediately after the completion of their installation. Heating systems are filled with water through the return pipeline, that is, from the bottom up.

With this method, the liquid and air go in the same direction, which, according to the laws of physics, with contributes to the removal of air masses from the system. Removal occurs in one way: through outlets, a tank or plungers of heating systems.

If the filling of heating networks occurs too quickly, air pockets may occur due to the filling of risers with water faster than heating devices of heating systems. pass under the lower value of the working pressure of 100 kilo Pascal and the test pressure of 300 kilo Pascal.

Checking the heating networks takes place only with the boiler and expansion tank disconnected.

Heating systems are not monitored during winter. If they have worked without breakdowns for up to about three months, then the commissioning of heating networks can be carried out without hydraulic tests. When checking closed heating systems, inspection work must be carried out before closing the furrows. If you plan to insulate heating networks, then - before installing it.

According to SNiP, after testing heating systems, they are washed, and a coupling with a cross section of 60 to 80 mm2 is mounted at their lowest point. Water flows through it. Washing of heating networks done with cold water several times until it becomes transparent. Approval of heating systems occurs if within 5 minutes the test pressure in the pipeline does not change by more than 20 kilo Pascal.

Hydraulic test of the heating and water supply system (video)

Hydraulic testing of heating networks and water supply systems

After completion of hydraulic testing of heating systems according to SNiP, an act of hydraulic testing of heating networks and water supply systems is drawn up, indicating the compliance of the pipeline parameters.

According to SNiP, its form contains the following information:

• the title of the position of the head of the enterprise providing services to heat networks;
• his signature and initials, as well as the date of verification;
• data on the chairman of the commission, as well as its members;
• information about the parameters of heating networks: lengths, names, etc.;
• conclusions on the control, conclusion of the commission.

Adjustment of the characteristics of heating mains is carried out by SNiP 3.05.03-85. According to the specified SNiP, it rules apply to all highways, which transport water up to 220˚С and steam up to 440˚С.

For the documentary completion of the hydraulic testing of the water supply, an act is drawn up for the external water supply in accordance with SNiP 3.05.01-85. According to SNiP, the act contains the following information:

• system name;
• the name of the organization of technical supervision;
• data on the value of the test pressure and test time;
• pressure drop data;
• presence or absence of signs of damage to the pipeline;
• the date of the check;
• withdrawal of the commission.

The act is certified by a representative of the supervisory organization.

There are 4 types of heat network tests:

1. For strength and tightness (crimping). It is carried out at the manufacturing stage before applying insulation. When used annually.
2. at design temperature. Carried out: in order to check the operation of expansion joints and fix their working position, to determine the integrity of fixed supports (1r. in 2 years). Tests are carried out during the manufacture of networks before applying insulation.
3. hydraulic. They are carried out in order to determine: the actual consumption of water by consumers, the actual hydraulic characteristics of the pipeline and the identification of areas with increased hydraulic resistance (1 time in 3-4 years).
4. Thermal testing. To determine the actual heat loss (1 time in 3-4 years). Tests are carried out according to the following dependence:

Q = cG(t 1 - t 2) £ Q norms = q l *l,

where q l - heat losses of 1 m of pipeline, are determined according to SNiP “Thermal insulation of pipelines and equipment”.

Heat losses are determined by the temperature at the end of the section.

Strength and tightness tests.

There are 2 types of tests:

1. hydraulic.
2. Pneumatic. Checked at t n<0 и невозможности подогрева воды и при её отсутствии.

Hydraulic tests.

Devices: 2 manometers (working and control) class above 1.5%, manometer diameter not less than 160mm, scale 4/3 of the test pressure.

Order of conduct:

1. Shut off the test area with plugs. Replace gland compensators with plugs or inserts. Open all bypass lines and valves if they cannot be replaced with plugs.
2. The test pressure is set = 1.25R slave, but not more than the working pressure of the pipeline P y. Exposure 10 minutes.
3. The pressure is reduced to the working pressure, at which the inspection is carried out. Leaks are controlled by: pressure drop on the pressure gauge, obvious leaks, characteristic noise, fogging of the pipe. At the same time, the position of the pipelines on the supports is controlled.

Pneumatic tests it is forbidden to carry out for: Above-ground pipelines; When combined with laying with other communications.

When testing, it is forbidden to test cast iron fittings. It is allowed to test ductile iron fittings at low pressures.

Devices: 2 pressure gauges, pressure source - compressor.

1. Filling at a rate of 0.3 MPa/hour.
2. Visual inspection at pressure P ≤ 0.3P tested. , but not more than 0.3 MPa. R isp \u003d 1.25R work.
3. The pressure rises to P tested, but not more than 0.3 MPa. Exposure 30 min.
4. Reduction of pressure to P slave, inspection. Leaks are determined by signs: a decrease in pressure on pressure gauges, noise, bubbling of a soap solution.

Safety precautions:

• during the inspection it is forbidden to go down into the trench;
• do not get exposed to the air stream.

Design Temperature Tests

Thermal networks with d ≥100mm are tested. At the same time, the design temperature in the supply pipeline and in the return must not exceed 100 0 С. The design temperature is maintained for 30 minutes, while the increase and decrease in temperature should not exceed 30 0 С/hour. This type of test is carried out after pressure testing of networks and elimination of gusts.

Tests to determine thermal and hydraulic losses

This test is carried out on a circulation circuit consisting of supply and return lines and a jumper between them, all branch subscribers are disconnected. In this case, the decrease in temperature along the movement along the ring is caused only by the heat losses of the pipelines. The test time is 2t to + (10-12 hours), t to - the run time of the temperature wave along the ring. Temperature wave - an increase in temperature by 10-20 0 С above the test temperature along the entire length of the temperature ring, is set by observers and the temperature change is recorded.

The test for hydraulic losses is carried out in two modes: at maximum flow and 80% of the maximum. For each of the modes, at least 15 readings should be taken with an interval of 5 minutes.

SNiP 3.05.03-85
________________
Registered by Rosstandart as SP 74.13330.2011. -
Database manufacturer's note.

BUILDING REGULATIONS

HEATING NETWORK

Introduction date 1986-07-01

DEVELOPED by the Orgenergostroy Institute of the USSR Ministry of Energy (L. Ya. Mukomel - leader of the topic; Candidate of Technical Sciences S. S. Yakobson).

INTRODUCED by the Ministry of Energy of the USSR.

PREPARED FOR APPROVAL by the Main Technical Regulation of the Gosstroy of the USSR (N. A. Shishov).

APPROVED by the Decree of the USSR State Committee for Construction of October 31, 1985 N 178.

With the entry into force of SNiP 3.05.03-85 "Heat Networks", SNiP III-30-74 "Water supply, sewerage and heat supply. External networks and structures" becomes invalid.

AGREED with the USSR Gosgortekhnadzor April 15, 1985

These rules apply to the construction of new, expansion and reconstruction of existing heating networks,

transporting hot water with temperature t and steam temperature t		200 degrees C and pressure 440 degrees C and pressure			2.5 MPa (25 kgf/sq.cm) 6.4 MPa (64 kgf/sq.cm)

from the source of thermal energy to heat consumers (buildings, structures).

1. GENERAL PROVISIONS

1. GENERAL PROVISIONS

1.1. When building new, expanding and reconstructing existing heating networks, in addition to the requirements of working drawings, work plans (PPR) and these rules, the requirements of SNiP 3.01.01-85, SNiP 3.01.03-84, SNiP III-4-80 and standards .

1.2. Works on the manufacture and installation of pipelines, which are subject to the requirements of the Rules for the Arrangement and Safe Operation of Steam and Hot Water Pipelines of the USSR Gosgortekhnadzor (hereinafter the Rules of the USSR Gosgortekhnadzor), must be carried out in accordance with the indicated Rules and the requirements of these rules and regulations.

1.3. Completed heating networks should be put into operation in accordance with the requirements of SNiP III-3-81.

2. EARTHWORKS

2.1. Earthworks and foundation works must be carried out in accordance with the requirements of SNiP III-8-76, SNiP 3.02.01-83, SN 536-81 and this section.

2.2. The smallest trench bottom width for channelless pipe laying should be equal to the distance between the outer side faces of the insulation of the outermost pipelines of heat networks (associated drainage) with the addition on each side for pipelines with a nominal diameter

the width of the pits in the trench for welding and insulating pipe joints during channelless laying of pipelines should be taken equal to the distance between the outer side faces of the insulation of the outermost pipelines with the addition of 0.6 m on each side, the length of the pits is 1.0 m and the depth from the lower edge of the pipeline insulation - 0.7 m, unless other requirements are justified by the working drawings.

2.3. The smallest width of the bottom of the trench in the case of channel laying of heat networks should be equal to the width of the channel, taking into account the formwork (in monolithic sections), waterproofing, associated drainage and drainage devices, the trench fastening structure with the addition of 0.2 m. In this case, the width of the trench should be at least 1 .0 m

If it is necessary for people to work between the outer edges of the channel structure and the walls or slopes of the trench, the clear width between the outer edges of the channel structure and the walls or slopes of the trench must be at least: 0.70 m - for trenches with vertical walls and 0.30 m - for trenches with slopes.

2.4. Backfilling of trenches during channelless and channel laying of pipelines should be carried out after preliminary tests of pipelines for strength and tightness, complete completion of insulation and construction and installation works.

Backfilling must be carried out in the specified technological sequence:

padding of sinuses between pipelines of channelless laying and the base;

simultaneous uniform backfilling of the sinuses between the walls of the trench and pipelines with channelless laying, as well as between the walls of the trench and channel, chamber with channel laying to a height of at least 0.20 m above pipelines, channels, chambers;

backfilling of the trench to design marks.

Backfilling of trenches (pits) to which additional external loads (except for the own weight of the soil) are not transferred, as well as trenches (pits) at intersections with existing underground utilities, streets, roads, driveways, squares and other structures of settlements and industrial sites should be carried out in accordance with the requirements of SNiP III-8-76.

2.5. After turning off the temporary dewatering devices, the channels and chambers must be visually inspected for the absence of groundwater in them.

3. CONSTRUCTIONS AND INSTALLATION OF BUILDING STRUCTURES

3.1. The construction and installation of building structures should be carried out in accordance with the requirements of this section and the requirements of:

SNiP III-15-76 - during the construction of monolithic concrete and reinforced concrete structures of foundations, supports for pipelines, chambers and other structures, as well as when monolithic joints;

SNiP III-16-80 - when installing prefabricated concrete and reinforced concrete structures;

SNiP III-18-75 - during the installation of metal structures of supports, superstructures for pipelines and other structures;

SNiP III-20-74 - for waterproofing channels (chambers) and other building structures (structures);

SNiP III-23-76 - when protecting building structures from corrosion.

3.2. The outer surfaces of the elements of channels and chambers supplied to the route must be coated with a coating or glued waterproofing in accordance with the working drawings.

The installation of channel elements (chambers) in the design position should be carried out in the technological sequence linked to the project for the production of work on installation and preliminary testing of pipelines for strength and tightness.

Support pads for sliding supports of pipelines must be installed at the distances provided for in SNiP II-D. 10-73* (II-36-73*).

3.3. Monolithic fixed shield supports must be made after the installation of pipelines in the shield support area.

3.4. In places where pipelines of channelless laying enter channels, chambers and buildings (structures), cases of bushings must be put on the pipes during their installation.

At the inlets of underground pipelines into buildings, devices must be made (in accordance with the working drawings) to prevent the penetration of gas into buildings.

3.5. Before installing the upper trays (plates), the channels must be cleared of soil, debris and snow.

3.6. The deviation of the slopes of the bottom of the channel of the heat network and drainage pipelines from the design is allowed by +/- 0.0005, while the actual slope must be at least the minimum allowable according to SNiP II-G.10-73* (II-36-73*) .

The deviation of the installation parameters of other building structures from the design ones must comply with the requirements of SNiP III-15-76, SNiP III-16-80 and SNiP III-18-75.

3.7. The construction organization project and the work execution project should provide for the advanced construction of drainage pumping stations and water outlet devices in accordance with the working drawings.

3.8. Before laying in the trench, drainage pipes must be inspected and cleaned of soil and debris.

3.9. Layer-by-layer filtering of drainage pipelines (except for pipe filters) with gravel and sand must be carried out using inventory separating forms.

3.10. The straightness of the sections of drainage pipelines between adjacent wells should be checked by looking at the light with a mirror before and after backfilling the trench. The pipe circumference reflected in the mirror must have the correct shape. The permissible horizontal deviation from the circumference should be no more than 0.25 of the pipe diameter, but no more than 50 mm in each direction.

Deviation from the correct form of a circle along the vertical is not allowed.

4. PIPING INSTALLATION

4.1. The installation of pipelines must be carried out by specialized installation organizations, while the installation technology must ensure high operational reliability of the pipelines.

4.2. Parts, elements of pipelines (compensators, sumps, insulated pipes, as well as pipeline assemblies and other products) must be manufactured centrally (at the factory, workshops, workshops) in accordance with standards, specifications and project documentation.

4.3. Laying of pipelines in a trench, channel or on above-ground structures should be carried out according to the technology provided for by the project for the production of works and excluding the occurrence of residual deformations in pipelines, violation of the integrity of the anti-corrosion coating and thermal insulation by using appropriate mounting devices, correct placement of simultaneously operating hoisting machines and mechanisms.

The design of fastening mounting devices to pipes must ensure the safety of the coating and insulation of pipelines.

4.4. The laying of pipelines within the shield support must be carried out using pipes of the maximum delivery length. In this case, the welded transverse seams of the pipelines should, as a rule, be located symmetrically with respect to the shield support.

4.5. Laying pipes with a diameter of more than 100 mm with a longitudinal or spiral seam should be carried out with a displacement of these seams by at least 100 mm. When laying pipes with a diameter of less than 100 mm, the offset of the joints must be at least three times the thickness of the pipe wall.

Longitudinal seams must be located within the upper half of the circumference of the pipes to be laid.

Steeply bent and stamped pipe bends may be welded together without a straight section.

Welding of branch pipes and bends into welded joints and bent elements is not allowed.

4.6. When installing pipelines, movable supports and suspensions must be displaced relative to the design position by the distance indicated in the working drawings, in the direction opposite to the movement of the pipeline in working condition.

In the absence of data in the working drawings, the movable supports and hangers of horizontal pipelines must be displaced, taking into account the correction for the outdoor temperature during installation, by the following values:

sliding supports and fastening elements of hangers to the pipe - by half of the thermal elongation of the pipeline at the point of fastening;

rollers of roller bearings - by a quarter of thermal elongation.

4.7. Spring hangers during installation of pipelines must be tightened in accordance with the working drawings.

During hydraulic testing of steam pipelines with a diameter of 400 mm or more, an unloading device should be installed in spring hangers.

4.8. Pipe fittings must be installed in a closed state. Flanged and welded fittings must be made without tension in the pipelines.

The deviation from perpendicularity of the plane of the flange welded to the pipe with respect to the axis of the pipe should not exceed 1% of the outer diameter of the flange, but be no more than 2 mm at the top of the flange.

4.9. Bellows (wavy) and stuffing box expansion joints should be mounted assembled.

When laying underground heating networks, the installation of expansion joints in the design position is allowed only after preliminary tests of pipelines for strength and tightness, backfilling of channelless pipelines, channels, chambers and shield supports.

4.10. Axial bellows and stuffing box compensators should be installed on pipelines without breaking the compensator axes and pipeline axes.

Permissible deviations from the design position of the connecting pipes of expansion joints during their installation and welding should not exceed those specified in the technical specifications for the manufacture and supply of expansion joints.

4.11. When mounting bellows compensators, their twisting relative to the longitudinal axis and sagging under the action of their own weight and the weight of adjacent pipelines are not allowed. Slinging expansion joints should be done only by the branch pipes.

4.12. The installation length of bellows and stuffing box expansion joints must be taken from the working drawings, taking into account the correction for the outside air temperature during installation.

Stretching expansion joints to the installation length should be carried out using the devices provided for by the design of the expansion joints, or tension mounting devices.

4.13. Stretching of the U-shaped compensator should be performed after the completion of the installation of the pipeline, quality control of welded joints (except for the closing joints used for tension) and fixing the structures of fixed supports.

The expansion joint must be stretched to the value specified in the working drawings, taking into account the correction for the outside air temperature when welding the closing joints.

The expansion joint must be stretched simultaneously from both sides at the joints located at a distance of at least 20 and not more than 40 pipeline diameters from the axis of symmetry of the expansion joint, using clamping devices, unless other requirements are justified by the project.

On the section of the pipeline between the joints used to stretch the expansion joint, it is not necessary to carry out preliminary displacement of supports and hangers in comparison with the project (working draft).

4.14. Immediately before assembling and welding pipes, it is necessary to visually inspect each section for the absence of foreign objects and debris in the pipeline.

4.15. The deviation of the slope of pipelines from the design is allowed by +/- 0.0005. In this case, the actual slope must be at least the minimum allowable according to SNiP II-G.10-73 * (II-36-73 *) .

The movable supports of the pipelines must be adjacent to the supporting surfaces of the structures without gap and distortion.

4.16. When performing installation work, the following types of hidden work are subject to acceptance with the preparation of survey reports in the form given in SNiP 3.01.01-85: preparation of the surface of pipes and welded joints for anti-corrosion coating; implementation of anticorrosive coating of pipes and welded joints.

An act should be drawn up on the stretching of compensators in the form given in the mandatory Appendix 1.

4.17. Protection of heat networks from electrochemical corrosion must be carried out in accordance with the Instructions for the protection of heat networks from electrochemical corrosion, approved by the USSR Ministry of Energy and the RSFSR Ministry of Housing and Communal Services and agreed with the USSR State Construction Committee.

5. ASSEMBLY, WELDING AND QUALITY CONTROL OF WELD JOINTS

5.1. Welders are allowed to tack and weld pipelines if they have documents for the right to carry out welding work in accordance with the Rules for the certification of welders, approved by the USSR Gosgortekhnadzor.

5.2. Before being allowed to work on welding joints of pipelines, the welder must weld a tolerance joint under production conditions in the following cases:

with a break in work for more than 6 months;

when welding pipelines with a change in the group of steel, welding consumables, technology or welding equipment.

On pipes with a diameter of 529 mm or more, it is allowed to weld half the perimeter of the tolerance joint; at the same time, if the tolerance joint is a vertical fixed joint, the ceiling and vertical sections of the seam should be welded.

The tolerance joint must be of the same type with the production one (the definition of the same type of joint is given in the Rules for the certification of welders of the USSR Gosgortekhnadzor).

The tolerance joint is subject to the same types of control that are subject to production welded joints in accordance with the requirements of this section.

Manufacturing jobs

5.3. The welder is obliged to knock out or build up a brand at a distance of 30-50 mm from the joint from the side accessible for inspection.

5.4. Before assembling and welding, it is necessary to remove the end caps, clean the edges and the inner and outer surfaces of the pipes adjacent to them to a width of at least 10 mm.

5.5. Welding methods, as well as types, structural elements and dimensions of welded joints of steel pipelines must comply with GOST 16037-80.

5.6. Joints of pipelines with a diameter of 920 mm or more, welded without the remaining backing ring, must be made with welding of the weld root inside the pipe. When welding inside the pipeline, the responsible contractor must be issued a work permit for the performance of high-risk work. The procedure for issuing and the form of the work permit must comply with the requirements of SNiP III-4-80.

5.7. When assembling and welding pipe joints without a backing ring, the offset of the edges inside the pipe should not exceed:

for pipelines that are subject to the requirements of the USSR Gosgortekhnadzor Rules, in accordance with these requirements;

for other pipelines - 20% of the pipe wall thickness, but not more than 3 mm.

At the joints of pipes assembled and welded on the remaining backing ring, the gap between the ring and the inner surface of the pipe should not exceed 1 mm.

5.8. Assembly of pipe joints for welding should be carried out using mounting centering devices.

Editing smooth dents at the ends of pipes for pipelines that are not subject to the requirements of the USSR Gosgortekhnadzor Rules is allowed if their depth does not exceed 3.5% of the pipe diameter. Sections of pipes with deeper dents or tears should be cut out. The ends of pipes with nicks or chamfers with a depth of 5 to 10 mm should be cut off or corrected by surfacing.

5.9. When assembling a joint using tacks, their number should be for pipes with a diameter of up to 100 mm - 1 - 2, with a diameter of more than 100 to 426 mm - 3 - 4. For pipes with a diameter of more than 426 mm, tacks should be placed every 300-400 mm around the circumference.

Tacks should be evenly spaced around the perimeter of the joint. The length of one tack for pipes with a diameter of up to 100 mm - 10 - 20 mm, a diameter of more than 100 to 426 mm - 20 - 40, a diameter of more than 426 mm - 30 - 40 mm. The height of the tack should be with a wall thickness S up to 10 mm - (0.6 - 0.7) S, but not less than 3 mm, with a larger wall thickness - 5 - 8 mm.

The electrodes or welding wire used for tacks must be of the same grade as for welding the main seam.

5.10. Welding of pipelines, which are not subject to the requirements of the Rules of the USSR Gosgortekhnadzor, is allowed to be carried out without heating the welded joints:

at an outdoor temperature of up to minus 20 degrees C - when using carbon steel pipes with a carbon content of not more than 0.24% (regardless of the pipe wall thickness), as well as low-alloy steel pipes with a wall thickness of not more than 10 mm;

at an outdoor temperature of up to minus 10 degrees C - when using pipes made of carbon steel with a carbon content of more than 0.24%, as well as pipes made of low-alloy steel with a wall thickness of more than 10 mm.

At a lower outdoor temperature, welding should be carried out in special booths, in which the air temperature in the area of ​​the welded joints must be maintained not lower than the specified one.

It is allowed to carry out welding work in the open air with heating of the pipe ends to be welded over a length of at least 200 mm from the joint to a temperature of at least 200 degrees C. After welding is completed, a gradual decrease in the temperature of the joint and the adjacent pipe zone should be ensured by covering them with an asbestos sheet or using another method.

Welding (at negative temperature) of pipelines that are subject to the requirements of the USSR Gosgortekhnadzor Rules must be carried out in compliance with the requirements of these Rules.

In case of rain, wind and snowfall, welding work may only be carried out if the welder and the welding site are protected.

5.11. Welding of galvanized pipes should be carried out in accordance with SNiP 3.05.01-85.

5.12. Before welding pipelines, each batch of welding consumables (electrodes, welding wire, fluxes, shielding gases) and pipes must be subjected to incoming inspection:

for the presence of a certificate with verification of the completeness of the data given in it and their compliance with the requirements of state standards or technical specifications;

for the presence on each box or other packaging of an appropriate label or tag with verification of the data given on it;

for the absence of damage (damage) to the packaging or the materials themselves. If damage is found, the question of the possibility of using these welding consumables must be decided by the organization performing the welding;

on the technological properties of electrodes in accordance with GOST 9466-75 or departmental regulations approved in accordance with SNiP 1.01.02-83.

5.13. When applying the main seam, it is necessary to completely cover and digest the potholders.

Quality control

5.14. Quality control of welding works and welded joints of pipelines should be carried out by:

checking the serviceability of welding equipment and measuring instruments, the quality of the materials used;

operational control during assembly and welding of pipelines;

external inspection of welded joints and measurements of weld dimensions;

checking the continuity of joints by non-destructive control methods - radiographic (X-ray or gamma rays) or ultrasonic flaw detection in accordance with the requirements of the Rules of the USSR Gosgortekhnadzor, GOST 7512-82, GOST 14782-76 and other standards approved in the prescribed manner. For pipelines that are not subject to the Rules of the USSR Gosgortekhnadzor, it is allowed to use magnetographic control instead of radiographic or ultrasonic testing;

mechanical tests and metallographic studies of control welded joints of pipelines, which are subject to the requirements of the USSR Gosgortekhnadzor Rules, in accordance with these Rules;

strength and tightness tests.

5.15. During the operational quality control of welded joints of steel pipelines, it is necessary to check the compliance with the standards of structural elements and dimensions of welded joints (blunting and cleaning of edges, the size of the gaps between the edges, the width and reinforcement of the weld), as well as the technology and mode of welding, the quality of welding materials, tacks and weld seam.

5.16. All welded joints are subject to external inspection and measurement.

Joints of pipelines welded without backing ring with welding of the root of the seam are subjected to external inspection and measurement of the dimensions of the seam outside and inside the pipe, in other cases - only outside. Before inspection, the weld and adjacent pipe surfaces must be cleaned of slag, splashes of molten metal, scale and other contaminants to a width of at least 20 mm (on both sides of the weld).

The results of an external examination and measurement of the dimensions of welded joints are considered satisfactory if:

there are no cracks of any size and direction in the seam and the adjacent area, as well as undercuts, sagging, burns, unwelded craters and fistulas;

the dimensions and number of volumetric inclusions and recessions between the rollers do not exceed the values ​​given in Table. 1;

the dimensions of lack of penetration, concavity and excess penetration at the root of the weld of butt joints made without the remaining backing ring (if it is possible to inspect the joint from inside the pipe) do not exceed the values ​​given in Table. 2.

Joints that do not meet the listed requirements are subject to correction or removal.

Table 1

	Maximum allowable linear size of the defect, mm	Maximum admissible number of defects for any 100 mm of weld length
Volumetric inclusion of a rounded or elongated shape with a nominal wall thickness of the welded pipes in butt joints or a smaller leg of the weld in fillet joints, mm:
St. 5.0 to 7.5
Recession (deepening) between the beads and scaly structure of the weld surface at the nominal wall thickness of the welded pipes in butt joints or with a smaller leg of the weld in fillet joints, mm:
		Not limited

table 2

pipelines, to which USSR Gosgortekhnadzor rules		Maximum allowable height (depth), % of nominal wall thickness	The maximum allowable total length along the perimeter of the joint
Spread	Concavity and lack of penetration at the root of the seam Excess penetration	10, but not more than 2 mm 20, but not more than 2 mm	20% perimeter
Do not apply	Concavity, excess penetration and lack of penetration at the root of the seam		1/3 perimeter

5.17. Welded joints are subjected to continuity testing by non-destructive testing methods:

pipelines that are subject to the requirements of the USSR Gosgortekhnadzor Rules, with an outer diameter of up to 465 mm - in the volume provided for by these Rules, with a diameter of more than 465 to 900 mm in a volume of at least 10% (but not less than four joints), with a diameter of more than 900 mm - in the volume not less than 15% (but not less than four joints) of the total number of joints of the same type made by each welder;

pipelines that are not subject to the requirements of the USSR Gosgortekhnadzor Rules, with an outer diameter of up to 465 mm in a volume of at least 3% (but not less than two joints), with a diameter of more than 465 mm - in the amount of 6% (but not less than three joints) of the total number of joints of the same type performed by each welder; in the case of checking the continuity of welded joints using magnetographic testing, 10% of the total number of joints subjected to testing must be checked, in addition, by radiographic method.

5.18. 100% of welded joints of pipelines of heat networks laid in impassable channels under the carriageway, in cases, tunnels or technical corridors together with other engineering communications, as well as at intersections should be subjected to non-destructive control methods:

railways and tram tracks - at a distance of at least 4 m, electrified railways - at least 11 m from the axis of the outermost track;

railways of the general network - at a distance of at least 3 m from the nearest subgrade structure;

motorways - at a distance of at least 2 m from the edge of the carriageway, the reinforced roadside strip or the sole of the embankment;

underground - at a distance of at least 8 m from the structures;

power, control and communication cables - at a distance of at least 2 m;

gas pipelines - at a distance of at least 4 m;

main gas pipelines and oil pipelines - at a distance of at least 9 m;

buildings and structures - at a distance of at least 5 m from walls and foundations.

5.19. Welded seams should be rejected if cracks, non-welded craters, burns, fistulas, as well as lack of penetration at the root of the weld made on the backing ring are found during testing by non-destructive testing methods.

5.20. When checking by radiographic method the welds of pipelines, which are subject to the requirements of the Rules of the USSR Gosgortekhnadzor, pores and inclusions are considered acceptable defects, the dimensions of which do not exceed the values ​​\u200b\u200bspecified in Table. 3.

Table 3

Rated wall thickness	Maximum permissible dimensions of pores and inclusions, mm						Total pore length and
	individual		clusters				inclusions
	width (diameter)		width (diameter)		width (diameter)		for any 100 mm seam, mm
Over 2.0 to 3.0

The height (depth) of lack of penetration, concavity and excess penetration at the root of the joint weld, made by one-sided welding without a backing ring, should not exceed the values ​​\u200b\u200bspecified in Table. 2.

Permissible defects in welds according to the results of ultrasonic testing are considered to be defects, measured characteristics, the number of which does not exceed those indicated in Table. 4.

Table 4

Nominal wall thickness	artificial size	Permissible conditional	The number of defects for any 100 mm of the seam
pipes, mm	corner reflector ("notches"), mm x mm	individual defect length, mm	large and small in total	major
4.0 to 8.0
St. 8.0" 14.5
Notes: 1. A defect is considered to be large if its nominal length exceeds 5.0 mm with a wall thickness of up to 5.5 mm and 10 mm with a wall thickness of more than 5.5 mm. If the conditional length of the defect does not exceed the specified values, it is considered small. 2. In electric arc welding without a backing ring with one-sided access to the seam, the total conditional length of defects located at the root of the seam is allowed up to 1/3 of the pipe perimeter. 3. The amplitude level of the echo signal from the measured defect should not exceed the amplitude level of the echo signal from the corresponding artificial corner reflector ("notch") or an equivalent segmental reflector.

5.21. For pipelines that are not subject to the requirements of the USSR Gosgortekhnadzor Rules, pores and inclusions whose dimensions do not exceed the maximum allowable in accordance with GOST 23055-78 for welded joints of the 7th class, as well as lack of penetration, concavity and excess penetration at the root of the weld, made by one-sided electric arc welding without a backing ring, the height (depth) of which should not exceed the values ​​\u200b\u200bspecified in Table. 2.

5.22. If non-destructive testing methods reveal unacceptable defects in the welds of pipelines that are subject to the requirements of the Rules of the USSR Gosgortekhnadzor, a repeated quality control of the welds established by these Rules should be carried out, and in the welds of pipelines that are not subject to the requirements of the Rules, - in twice the number of joints according to compared with that specified in clause 5.17.

If unacceptable defects are detected during the re-inspection, all joints made by this welder should be checked.

5.23. Correction by local sampling and subsequent welding (without re-welding the entire joint) is subject to sections of the weld with unacceptable defects, if the dimensions of the sample after removing the defective section do not exceed the values ​​\u200b\u200bspecified in Table. 5.

Welded joints, in the seams of which, in order to correct the defective area, it is required to make a sample with sizes larger than those allowed according to Table. 5 must be completely removed.

Table 5

sampling depth, % nominal wall thickness of welded pipes (calculated height of the weld section)	Length, % of the nominal outer perimeter of the pipe (nozzle)
St. 25 to 50	No more than 50
Note. When correcting several sections in one connection, their total length may exceed that indicated in Table. 5 no more than 1.5 times at the same depth standards.

5.24. Undercuts should be corrected by surfacing thread rollers with a width of not more than 2.0 - 3.0 mm. Cracks must be drilled at the ends, cut down, carefully cleaned and welded in several layers.

5.25. All repaired areas of welded joints should be checked by visual inspection, radiographic or ultrasonic inspection.

5.26. On the executive drawing of the pipeline, drawn up in accordance with SNiP 3.01.03-84, the distances between welded joints, as well as from wells, chambers and subscriber inputs to the nearest welded joints, should be indicated.

6. THERMAL INSULATION OF PIPING

6.1. Installation of heat-insulating structures and protective coatings must be carried out in accordance with the requirements of SNiP III-20-74 and this section.

6.2. Welded and flanged joints should not be insulated to a width of 150 mm on both sides of the joints before testing pipelines for strength and tightness.

6.3. The possibility of performing insulation work on pipelines subject to registration in accordance with the Rules of the USSR Gosgortekhnadzor, before performing tests for strength and tightness, must be agreed with the local authority of the USSR Gosgortekhnadzor.

6.4. When performing filling and backfill insulation during channelless laying of pipelines, it is necessary to provide for temporary devices in the project for the production of works to prevent the pipeline from surfacing, as well as from getting into the soil insulation.

7. TRANSITIONS OF HEAT NETWORKS THROUGH DRIVERS AND ROADS

7.1. The performance of work during underground (above-ground) crossing of railway and tram tracks, roads, city passages by heating networks should be carried out in accordance with the requirements of these rules, as well as SNiP III-8-76.

7.2. When puncturing, punching, horizontal drilling or other methods of trenchless laying of cases, the assembly and tacking of the sections (pipes) of the case must be performed using a centralizer. The ends of the welded links (pipes) must be perpendicular to their axes. Fractures of the axes of the links (pipes) of the cases are not allowed.

7.3. Reinforced shotcrete-concrete anti-corrosion coating of cases during their trenchless laying should be made in accordance with the requirements of SNiP III-15-76.

7.4. Pipelines within the case should be made of pipes of the maximum delivery length.

7.5. The deviation of the axis of transition cases from the design position for gravity condensate pipelines should not exceed:

vertically - 0.6% of the length of the case, provided that the design slope of the condensate pipelines is ensured;

horizontally - 1% of the length of the case.

The deviation of the transition case axis from the design position for the remaining pipelines should not exceed 1% of the case length.

8. TESTING AND FLUSHING (BLOWING) OF PIPING

8.1. After completion of construction and installation works, pipelines must be subjected to final (acceptance) tests for strength and tightness. In addition, condensate pipelines and pipelines of water heating networks must be washed, steam pipelines - purged with steam, and pipelines of water heating networks with an open heat supply system and hot water supply networks - washed and disinfected.

Pipelines laid without channels and in impassable channels are also subject to preliminary tests for strength and tightness in the course of construction and installation works.

8.2. Preliminary testing of pipelines should be carried out before installing stuffing box (bellows) compensators, sectional valves, closing channels and backfilling pipelines without channel laying and channels.

Preliminary testing of pipelines for strength and tightness should be carried out, as a rule, in a hydraulic way.

At negative temperatures of the outside air and the impossibility of heating water, as well as in the absence of water, it is allowed, in accordance with the project for the production of works, to perform preliminary tests by pneumatic means.

It is not allowed to perform pneumatic tests of above-ground pipelines, as well as pipelines laid in the same channel (section) or in the same trench with existing utilities.

8.3. Pipelines of water heating networks should be tested with a pressure equal to 1.25 working pressure, but not less than 1.6 MPa (16 kgf / sq. cm), steam pipelines, condensate pipelines and hot water supply networks - with a pressure equal to 1.25 working pressure, unless other requirements substantiated by the project (working draft).

8.4. Before performing tests for strength and tightness, it is necessary:

to carry out quality control of welded joints of pipelines and correction of detected defects in accordance with the requirements of Sec. 5;

disconnect the tested pipelines from the existing ones and from the first stop valves installed in the building (structure) with plugs;

install plugs at the ends of the tested pipelines and instead of stuffing box (bellows) compensators, sectional valves during preliminary tests;

provide access throughout the tested pipelines for their external inspection and inspection of welds for the duration of the tests;

fully open fittings and bypass lines.

The use of shut-off valves to disconnect the tested pipelines is not allowed.

Simultaneous preliminary tests of several pipelines for strength and tightness are allowed to be carried out in cases justified by the work design.

8.5. Pressure measurements when testing pipelines for strength and tightness should be carried out using two duly certified (one - control) spring pressure gauges of class at least 1.5 with a body diameter of at least 160 mm and a scale with a nominal pressure of 4/3 of the measured pressure.

8.6. Testing of pipelines for strength and tightness (density), their purging, washing, disinfection must be carried out according to technological schemes (agreed with operating organizations) that regulate the technology and safety of work (including the boundaries of protected zones).

8.7. On the results of testing pipelines for strength and tightness, as well as on their flushing (purging), acts should be drawn up in the forms given in mandatory appendices 2 and 3.

Hydraulic tests

8.8. Piping tests should be carried out in compliance with the following basic requirements:

test pressure must be provided at the top point (mark) of the pipelines;

the water temperature during testing should not be lower than 5 degrees C;

at a negative outdoor temperature, the pipeline must be filled with water at a temperature not exceeding 70 degrees C and it must be possible to fill and empty it within 1 hour;

when gradually filling with water, air must be completely removed from the pipelines;

the test pressure must be maintained for 10 minutes and then reduced to working pressure;

at operating pressure, the pipeline must be inspected along its entire length.

8.9. The results of hydraulic tests for the strength and tightness of the pipeline are considered satisfactory if during their implementation there was no pressure drop, no signs of rupture, leakage or fogging in welds, as well as leaks in the base metal, flange joints, fittings, compensators and other elements of pipelines , there are no signs of shift or deformation of pipelines and fixed supports.

Pneumatic tests

8.10. Pneumatic tests should be performed for steel pipelines with a working pressure of not more than 1.6 MPa (16 kgf / sq. cm) and a temperature of up to 250 degrees C, mounted from pipes and parts tested for strength and tightness (density) by manufacturers in accordance with GOST 3845-75 (at the same time, the factory test pressure for pipes, fittings, equipment and other products and parts of the pipeline must be 20% higher than the test pressure adopted for the installed pipeline).

The installation of cast iron fittings (except for ductile iron valves) is not allowed for the duration of the test.

8.11. Filling the pipeline with air and raising the pressure should be done smoothly at a rate of no more than 0.3 MPa (3 kgf / sq. cm) per hour. Visual inspection of the route [entrance to the security (dangerous) zone, but without descending into the trench] is allowed at pressure equal to 0.3 test, but not more than 0.3 MPa (3 kgf / sq. cm).

For the period of inspection of the route, the pressure increase must be stopped.

When the test pressure is reached, the pipeline must be held to equalize the air temperature along the length of the pipeline. After equalizing the air temperature, the test pressure is maintained for 30 minutes and then gradually decreases to 0.3 MPa (3 kgf / sq. cm), but not higher than the working pressure of the coolant; at this pressure, pipelines are inspected with a mark of defective places.

Leaks are identified by the sound of escaping air, by bubbling when welding joints and other areas are covered with soapy emulsion, and by other methods.

Defects are eliminated only when the excess pressure is reduced to zero and the compressor is turned off.

8.12. The results of preliminary pneumatic tests are considered satisfactory if during their conduct there was no pressure drop on the pressure gauge, no defects were found in welds, flange joints, pipes, equipment and other elements and products of the pipeline, there are no signs of shear or deformation of the pipeline and fixed supports.

8.13. Pipelines of water networks in closed heat supply systems and condensate pipelines should, as a rule, be subjected to hydropneumatic flushing.

Hydraulic flushing is allowed with reuse of flushing water by passing it through temporary sumps installed in the direction of water movement at the ends of the supply and return pipelines.

Flushing, as a rule, should be carried out with process water. Flushing with utility and drinking water is allowed with justification in the project for the production of works.

8.14. Pipelines of water networks of open heat supply systems and hot water supply networks must be flushed hydropneumatically with drinking-quality water until the flushing water is completely clarified. Upon completion of flushing, the pipelines must be disinfected by filling them with water containing active chlorine at a dose of 75-100 mg / l with a contact time of at least 6 hours. Pipelines with a diameter of up to 200 mm and a length of up to 1 km are allowed, in agreement with the local sanitary authorities. epidemiological service, do not expose to chlorination and limit yourself to washing with water that meets the requirements of GOST 2874-82.

After washing, the results of laboratory analysis of samples of wash water must comply with the requirements of GOST 2874-82. A conclusion is drawn up on the results of washing (disinfection) by the sanitary and epidemiological service.

8.15. The pressure in the pipeline during flushing should not be higher than the working one. The air pressure during hydropneumatic flushing should not exceed the working pressure of the coolant and be no higher than 0.6 MPa (6 kgf / sq. cm).

Water velocities during hydraulic flushing must not be lower than the calculated coolant velocities indicated in the working drawings, and during hydropneumatic flushing, exceed the calculated ones by at least 0.5 m/s.

8.16. Steam pipelines must be purged with steam and vented to the atmosphere through specially installed purge pipes with shutoff valves. To warm up the steam pipeline, all start-up drains must be open before purging. The heating rate should ensure the absence of hydraulic shocks in the pipeline.

The steam velocities during the blowing of each section must be at least the operating velocities for the design parameters of the coolant.

9. ENVIRONMENTAL PROTECTION

9.1. During the construction of new, expansion and reconstruction of existing heating networks, environmental protection measures should be taken in accordance with the requirements of SNiP 3.01.01-85 and this section.

9.2. It is not allowed without agreement with the relevant service: to carry out excavation at a distance of less than 2 m to tree trunks and less than 1 m to shrubs; movement of goods at a distance of less than 0.5 m to crowns or tree trunks; storage of pipes and other materials at a distance of less than 2 m to tree trunks without the installation of temporary enclosing (protective) structures around them.

9.3. Flushing of pipelines in a hydraulic way should be carried out with the reuse of water. Emptying of pipelines after washing and disinfection should be carried out at the places indicated in the project for the production of works and agreed with the relevant services.

9.4. The territory of the construction site after the completion of construction and installation work must be cleared of debris.

Annex 1. ACT ON STRETCHING OF COMPENSATORS

ANNEX 1
Mandatory

____________________________ "_____" _________________ 19_____

Commission consisting of:

(last name, first name, patronymic, position)

_____________________________________________________________,

1. An extension of the compensators listed in the table was presented for inspection and acceptance in the area from the chamber (picket, mine) No. _______ to the chamber (picket, mine) No. _______.

Compensator number	Drawing number	Compensation type	Stretching size, mm		Temperature outdoor
according to the drawing			design	actual	air, deg.С

2. The work was carried out according to the design and estimate documentation ____________

_______________________________________________________________

COMMISSION DECISION

The works were performed in accordance with the design and estimate documentation, state standards, building codes and regulations and meet the requirements for their acceptance.

(signature)

(signature)

Appendix 2. ACT ON TESTING PIPELINES FOR STRENGTH AND TIGHTNESS

APPENDIX 2
Mandatory

_____________________ "_____" ____________ 19____

Commission consisting of:

representative of the construction and installation organization _________________

_____________________________________________________________,
(last name, first name, patronymic, position)

representative of the technical supervision of the customer _____________________

_____________________________________________________________,
(last name, first name, patronymic, position)

representative of the operating organization ______________________

_____________________________________________________________
(last name, first name, patronymic, position)

inspected the work performed by ___________________________

_____________________________________________________________,
(name of construction and installation organization)

and drew up this act as follows:

1. ________________ are presented for examination and acceptance.

_____________________________________________________________
(hydraulic or pneumatic)

pipelines tested for strength and tightness and listed in the table, in the section from chamber (picket, mine) No. ________ to chamber (picket, mine) No. _________ of the route ___________

Length __________ m.
(pipeline name)

Pipeline	test pressure, MPa (kgf/sq.cm)	Duration, min	External inspection at pressure, MPa (kgf/sq.cm)

2. The work was carried out according to the design and estimate documentation __________________

_____________________________________________________________________
(name of design organization, drawing numbers and date of drawing up)

COMMISSION DECISION

Representative of the construction and installation organization ________________
(signature)

Representative of the technical supervision of the customer _____________________
(signature)

(signature)

Appendix 3. ACT ON FLUSHING (BLOWING) OF PIPELINES

APPENDIX 3
Mandatory

_______________________________________ "____" _______________ 19_____

Commission consisting of:

representative of the construction and installation organization ________________

_____________________________________________________________,
(last name, first name, patronymic, position)

representative of the technical supervision of the customer _____________________

_____________________________________________________________,
(last name, first name, patronymic, position)

representative of the operating organization _____________________

_____________________________________________________________
(last name, first name, patronymic, position)

inspected the work performed by ____________________________

_____________________________________________________________,
(name of construction and installation organization)

and drew up this act as follows:

1. Flushing (purging) of pipelines in the section from chamber (picket, mine) No. __________ to chamber (picket, mine) No. ______ of route _______________________________________________________________________________

_____________________________________________________________________________________
(pipeline name)

length ___________ m.

Flushing (purging) performed ________________________________

_____________________________________________________________.
(medium name, pressure, flow rate)

2. The work was carried out according to the design and estimate documentation _________________

____________________________________________________________________

_____________________________________________________________________.
(name of design organization, drawing numbers and date of drawing up)

COMMISSION DECISION

The works were performed in accordance with the design estimates, standards, building codes and regulations and meet the requirements for their acceptance.

Representative of the construction and installation organization ________________
(signature)

Representative of the technical supervision of the customer _____________________
(signature)

Representative of the operating organization _____________________
(signature)

The text of the document is verified by:
official publication
M.: CITP Gosstroy of the USSR, 1986