Calculation of stretching expansion joints of thermal networks. Calculation of pre-stretching of the compensator during installation

Calculation of the U-shaped compensator consists in determining the minimum dimensions of the compensator sufficient to compensate for thermal deformations of the pipeline. By filling out the above form, you can calculate the compensating capacity of a U-shaped compensator of given dimensions.

The algorithm of this online program is based on the method for calculating a U-shaped compensator given in the Designer's Handbook "Heat Network Design" edited by A. A. Nikolaev.

The maximum stress in the back of the compensator is recommended to be taken in the range from 80 to 110 MPa.

It is recommended to take the optimal ratio of the compensator extension to the outer diameter of the pipe in the range H / Dн = (10 - 40), while the expansion joint extension of 10DN corresponds to the DN350 pipeline, and the extension of 40DN corresponds to the DN15 pipeline.

The optimal ratio of the width of the compensator to its reach is recommended to be taken in the range L / H = (1 - 1.5), although other values \u200b\u200bare accepted.

If an expansion joint of too large dimensions is required to compensate for the calculated thermal elongations, it can be replaced by two smaller expansion joints.

When calculating the thermal elongation of the pipeline, the temperature of the coolant should be taken as the maximum, and the temperature of the environment surrounding the pipeline as the minimum.

The following restrictions were taken into account:

The pipeline is filled with water or steam
The pipeline is made of steel pipe
Maximum temperature working environment does not exceed 200 °С
The maximum pressure in the pipeline does not exceed 1.6 MPa (16 bar)
The compensator is installed on a horizontal pipeline
The compensator is symmetrical, and its arms are of the same length
Fixed supports are considered absolutely rigid.
The pipeline does not experience wind pressure and other loads
The resistance of the friction forces of the movable supports during thermal elongation is not taken into account
Elbows are smooth

It is not recommended to place fixed supports at a distance of less than 10DN from the U-shaped compensator, since the transfer of the pinching moment of the support to it reduces flexibility.

Pipeline sections from fixed supports to the U-shaped compensator are recommended to be of the same length. If the compensator is not placed in the middle of the section, but is shifted towards one of the fixed supports, then the elastic deformation forces and stresses increase by about 20-40%, in relation to the values obtained for the compensator located in the middle.

To increase the compensating capacity, pre-stretching of the compensator is used. During installation, the compensator experiences a bending load, when heated, it assumes an unstressed state, and at maximum temperature it comes into tension. Preliminary stretching of the compensator by a value equal to half of the thermal elongation of the pipeline makes it possible to double its compensating capacity.

Application area

U-shaped compensators are used to compensate for thermal elongation of pipes in long straight sections, if there is no possibility of self-compensation of the pipeline due to turns in the heating network. The absence of compensators on rigidly fixed pipelines with a variable temperature of the working medium will lead to an increase in stresses that can deform and destroy the pipeline.

Flexible expansion joints are used

For above-ground laying for all pipe diameters, regardless of the parameters of the coolant.
When laying in channels, tunnels and common collectors on pipelines from DN25 to DN200 at a coolant pressure of up to 16 bar.
With channelless laying for pipes with a diameter of DN25 to DN100.
If the maximum medium temperature exceeds 50°C

Advantages

High compensating capacity
Maintenance Free
Easy to manufacture
Insignificant forces transmitted to fixed supports

Flaws

High pipe consumption
Large footprint
High hydraulic resistance

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 - head 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

1.1. 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 construction heating network should be taken 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 - 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 for channel laying of heat networks should be equal to the width of the channel, taking into account the formwork (on monolithic areas), waterproofing, associated drainage and drainage devices, trench fastening structures with an 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 testing of pipelines for strength and tightness, complete completion of insulating and construction installation work.

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 in case of channelless laying, as well as between the walls of the trench and channel, chamber in case of 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 foundations, supports for pipelines, chambers and other structures, as well as when embedding joints;

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

SNiP III-18-75 - during installation metal structures supports, span structures 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 installation and preliminary testing of pipelines for strength and tightness.

Support pads under sliding supports 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 pipeline inlets underground laying the buildings must be made (in accordance with the working drawings) devices that prevent the penetration of gas into the 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 heat network channel and drainage pipelines from the design one 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 correct form vertical circles are 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. Details, 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 hangers 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 compensators during their installation and welding should not exceed those specified in specifications for the manufacture and supply of compensators.

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 carried out 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 for stretching 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 garbage.

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 vertical fixed, ceiling and vertical sections seam.

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 steel pipes conductors 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 outside 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) pipelines, which are subject to the requirements of the Rules of the USSR Gosgortekhnadzor, 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 the electrodes in accordance with GOST 9466-75 or departmental normative documents 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 examination welded joints and measurement 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 Rules of the USSR Gosgortekhnadzor, 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 compliance with the standards 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 welding mode, the quality of welding materials, tacks and the weld.

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

Joints of pipelines welded without a 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. one;

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 corner connections, 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, for 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) total number the same type of joints 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:

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 seam 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 major defect is considered 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 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 are considered acceptable defects in the radiographic method of control at the root of a seam made on one side 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, % of 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 flaw detection.

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 thermal insulation structures and protective coatings must be produced 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 Gosgortechnadzor, before performing strength and tightness tests, must be agreed with the local authority of the USSR Gosgortekhnadzor.

6.4. When performing filler 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 floating up, as well as from getting into the soil insulation.

7. TRANSITIONS OF HEAT NETWORKS THROUGH DRIVERS AND ROADS

7.1. The performance of work at the 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 made 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, flushing, disinfection must be carried out according to technological schemes(coordinated with operating organizations), regulating 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 not more than 0.3 MPa (3 kgf / sq. cm) in 1 hour. visual inspection the route [entrance to the security (dangerous) zone, but without descending into the trench] is allowed at a pressure value 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 by reducing overpressure to zero and shutdown of the compressor.

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 systems heat supply 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 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 operating pressure 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, measures to protect environment 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 produce 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)

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

1.1. Products are allowed to be used in construction areas with an estimated outdoor temperature for designing heating systems of at least minus 40°C. The seismicity of construction areas is not more than nine points on the Richter scale.

1.2. Products are allowed to be used when the content of chlorides in the network water is not more than 250 mg/kg.

1.3. Products must be installed on straight sections of pipelines, limited by fixed supports. Only one product is allowed between fixed supports.

A deviation from straightness in plan and profile is allowed with the obligatory installation of guide supports in the same places at least two in front of each compensating device.

1.4. Way of accession to the pipeline - welding.

1.5. For any method of laying pipelines, except for underground channelless, the installation of compensating devices should be provided, as a rule, at one of the fixed supports.

1.6. On channelless underground heating networks, the product should be placed in the middle of the pipeline section, limited by fixed supports.

1.7. Before and after the compensating device, it is necessary to install guide supports, which exclude the movement of pipelines in the radial direction.

When channelless laying of the pipeline, the installation of guide supports is not required.

Examples of layouts for the bellows compensating device, guides and fixed supports are shown in the figure:

6.8. On sections of pipelines with bellows compensating devices, the use of suspension supports is not allowed.

6.9. When choosing fixed supports, the following factors should be considered:

Spacer force of the compensator;

Compensator stiffness force;

Friction in guides and sliding bearings;

The magnitude of the centrifugal force that occurs when the pipeline is bent.

Calculation of loads on end and intermediate fixed supports at various ways installation of bellows compensating devices is carried out at the stage of designing a heat network and is given in special literature.

6.10. The maximum distance between the fixed supports of the pipeline is determined by the formula:

where 0.9 is the safety factor, taking into account calculation inaccuracies and errors

installation features;

Compensating capacity of the compensator, mm

a - average coefficient of linear expansion of pipe steel at

heating from 0°С to t°С, mm/m°С;

t - design temperature of network water in the supply pipeline, °С;

t RO - design temperature outdoor air for system design

heating, taken equal to average temperature air most-

colder than the five-day period according to the chapter SNiP "Construction climatology

and geophysics”, °C.

1.8. Products do not require maintenance during operation and belong to the class of non-repairable products, they do not require the construction of special chambers, and when laying on the ground - platforms for maintenance.

Installation instructions.

2.1. Installation of products is carried out in accordance with the design of the pipeline, executed by the design organization.

2.2. Before installation, the products must be checked for compliance with their technical characteristics of the heating network project, as well as for the absence of mechanical damage.

2.3. When moving compensating devices during the installation period, measures must be taken to protect the product from shocks, shocks and exclude pollution or flooding of its internal cavity with groundwater.

2.4. When performing welding work, the ends of the insulation of the compensating device should be protected with detachable tin screens 0.8 ... 1 mm thick to prevent its ignition.

Installation of products is allowed to be carried out at an air temperature of at least minus 30 ° C.

2.5. Before welding the product to the pipeline, the deviations of the product connections with the pipeline are checked, which should not exceed the following values: nozzle alignment tolerance - 2 mm;

the tolerance of parallelism of the ends of the connecting pipes and connected pipes is 3 mm.

The maximum welding gap between the branch pipe and the pipeline is 2 mm.

2.6. The product should be installed on heat pipelines so that the direction of the arrow (if any) on the body of the compensating device coincides with the direction of movement of the coolant.

2.7. Products are mounted on the pipeline with preliminary stretching.

The length of the compensator during installation Lmount., mm is determined by the formula:

L builds.- building length of the compensator in the state of delivery, mm;

Compensating capacity of the compensator, mm;

A- coefficient of linear expansion of pipe steel,

removable 0.012 mm/m °С;

t hire. - the lowest air temperature during operation, °С;

L- the length of the compensator section between the fixed supports,

on which the compensator is mounted, m.

The mounting length of the compensating device is set by the installer.

The sections of the pipeline before and after the compensating device must be mounted and fixed in fixed supports so that the distance between the ends of the pipes at the installation site of the product corresponds to the installation length L mont. at ambient temperature at the moment of fixing the pipeline in the second fixed support; the ambient air temperature and the distance between the ends of the fixed pipes must be recorded in an act;

The compensating device is welded to one of the sections of the pipeline;

A universal mounting device is installed on the free connecting pipe of the product and the free end of the pipeline, with the help of which the compensator of the product is stretched to the junction with the pipeline, and the joint is welded;

Remove the mounting fixture from the product.

When expanding the compensator, it is necessary to ensure the same movement of the connecting pipes relative to the ends of the product.

If it is impossible to install the product in the middle of the straight section of the heat pipeline between the fixed supports, it is allowed to install it anywhere in the straight section of the heat pipeline. To do this, when the expansion joint is stretched, it is necessary to ensure the movement of the connecting pipes relative to the ends of the compensating device by inversely proportional lengths of the sections of the heat pipe between the product and the fixed supports.

2.9. The connection of the conductors-indicators of the product with a common signal system must be made after the completion of welding work, before insulating the joints of the connecting pipes with the heat conductor. Indicator conductors should not touch the metal of the pipes anywhere.

	bellows compensating device
	end fixed support

Instead of SNiP III-30-74

These rules apply to the construction of new, expansion and reconstruction of existing heating networks that transport hot water at temperature and pressure and steam at temperature and pressure from the source of thermal energy to heat consumers (buildings, structures).

1. General Provisions

1.2. Works on the manufacture and installation of pipelines, which are subject to the requirements of the Rules for the installation and safe operation steam and hot water pipelines of the Gosgortekhnadzor of the USSR (hereinafter referred to as the Rules of the Gosgortekhnadzor of the USSR), must be manufactured in accordance with the indicated Rules and the requirements of these rules and regulations.

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

2. Earthworks

2.1. Excavation and foundation work 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 extreme pipelines of heat networks (associated drainage) with the addition on each side for pipelines with a nominal diameter of up to 250 mm - 0.30 m, over 250 to 500 mm - 0 .40 m, over 500 to 1000 mm - 0.50 m; 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 - 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 trench width 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.

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 in case of channelless laying, as well as between the walls of the trench and channel, chamber in case of channel laying to a height of at least 0.20 m above pipelines, channels, chambers;

backfilling of the trench to design marks.

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. Structures 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 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-G.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 working drawings) to prevent gas from penetrating 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 the value, 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.

3.8. 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.

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

4. Installation of pipelines

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.

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

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.

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.

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.

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 for stretching 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 make a visual inspection of 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 the value. 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 concealed 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.

5. Assembly, welding and quality control of welded joints

General provisions

5.1. Welders are allowed to tack and weld pipelines if they have documents for the right to perform 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.

5.7. 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 Rules of the USSR Gosgortekhnadzor - 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.

Straightening 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.

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 outside temperature of up to minus 20 ° 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 outside air temperature of up to minus 10°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 when the welded pipe ends are heated for a length of at least 200 mm from the joint to a temperature of at least 200 ° 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;

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 USSR Gosgortekhnadzor Rules, GOST 7512-82, GOST 14782-76 and other standards approved in the prescribed manner. For pipelines that are not subject to the USSR Gosgortekhnadzor Rules, it is allowed to use magnetographic testing 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 Rules of the Gosgortekhnadzor of the USSR, 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 a 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 size 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

table 2

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 amount provided for by these Rules, with a diameter of more than 465 to 900 mm - in the amount of at least 10% (but not less than four joints), with a diameter of more than 900 mm - in a volume of at least 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 the amount 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 the same type joints made 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.

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.

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

Table 3

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

Notes: 1. A major defect is considered 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 Rules of the Gosgortekhnadzor of the USSR, pores and inclusions, the dimensions of which 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, are considered acceptable defects in the radiographic method of control at the root of the seam, 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 USSR Gosgortekhnadzor Rules, 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 a double 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.

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 in Table 5, must be completely removed.

Table 5

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

6. Thermal insulation of pipelines

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 must be agreed with the local authority of the USSR Gosgortekhnadzor before performing tests for strength and tightness.

7. Transitions of heating networks through driveways and roads

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 (purging) of pipelines

General provisions

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.

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 heat networks should be tested with a pressure equal to 1.25 working pressure, but not less than 1.6 MPa (16), steam pipelines, condensate pipelines and hot water supply networks - with a pressure equal to 1.25 working pressure, unless other requirements are justified by the project (working draft ).

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

carry out quality control of welded joints of pipelines and correction of detected defects in accordance with the requirements of Section 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.

8.6. 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 ° C;

at a negative outdoor 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;

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.

Pneumatic tests

8.10. Pneumatic tests should be performed for steel pipelines with a working pressure of not more than 1.6 MPa (16) 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, 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) per 1 hour. 3 test, but not more than 0.3 MPa (3).

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), 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.

8.13. 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.

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).

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 earthwork 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.

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

Annex 1

Mandatory

Act
about stretching compensators

____________________________ "_____" _________________ 19_____

Commission consisting of:

(last name, first name, patronymic, position)

inspected the work performed by ________________________________

________________________________________________________________________,

1. Stretching presented for inspection and acceptance

compensators listed in the table, in the area from the chamber (picket,

mine) N_______ to the camera (picket, mine) N_______.

───────────────────┬─────────┬────────┬─────────────────────┬───────────┐

Compensator number │ Number │ Type │ Value │Temperature│

according to the drawing │ drawing │ compen-│ extensions, mm │external │

│ │ sator ├──────────┬───────────┤air, °С│

│ │ │design│actual│ │

│ │ │ │ │ │

───────────────────┼─────────┼────────┼─────────┼───────────┼───────────┤

│ │ │ │ │ │

───────────────────┴─────────┴────────┴─────────┴───────────┴───────────┘

_________________________________________________________________________

drafting)

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)

Appendix 2

Mandatory

Act
on testing pipelines for strength and tightness

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)

_________________________________________________________________________

(last name, first name, patronymic, position)

________________________________________________________________________,

(name of construction and installation organization)

and drew up this act as follows:

1. _____________________ were presented for examination and acceptance

_________________________________________________________________________

(hydraulic or pneumatic)

pipelines tested for strength and tightness and listed in

table, in the section from the camera (picket, mine) N_______ to the camera

(picket, mines) N_________ routes ___________

Length __________ m.

(pipeline name)

─────────────────┬─────────────────┬─────────────────────┬──────────────┐

Pipeline │ Test │ Duration, │ Outdoor │

│ pressure, MPa │ min │ inspection at │

│ (kgf/sq.cm) │ │ 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

drafting)

Commission decision

Representative of the construction and installation organization _____________________

(signature)

Representative of the technical supervision of the customer _____________________

(signature)

Appendix 3

Mandatory

Act
on flushing (purging) pipelines

_____________________ "_____" ____________ 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) is presented for inspection and acceptance

pipelines in the section from the chamber (picket, mine) N__________ to the chamber

(picket, mines) N______ routes __________________________________________

_________________________________________________________________________

(pipeline name)

length ___________ m.

Flushing (purging) was carried out by _____________________________________________

________________________________________________________________________.

(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

drafting)

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 _____________________

Installation of heat networks, which must be carried out by the in-line method, includes earthwork, assembly and welding, stone, concrete, reinforced concrete, insulating, pressure testing, carpentry and other works.

With a properly organized flow method of construction, work is carried out in a certain technological sequence. The flow is organized in such a way as to most economically dispose of forces and means, to perform a large amount of work in short time, at low cost and with high quality construction.

Heating networks in cities and other settlements are laid in lanes specially designated for the construction of engineering structures, parallel to the red lines of streets, roads and driveways outside the carriageway and green spaces. When justified, it is possible to lay networks under the carriageway and sidewalks.

For heating networks, underground laying is mainly provided, less often - aboveground(in the territories of enterprises, outside the city, with a high level of groundwater, in permafrost areas and other cases where underground laying is impossible or impractical).

When laying underground, pipelines of heating networks (heat pipelines) are laid in channels - special building structures, protecting pipelines, or channelless. Channels can be through and non-through. Depending on the accepted design of underground laying (in impassable or through channels, collectors), it is allowed to lay heat networks together with other engineering networks(water supply, communication cables, power cables, pressure sewerage).

With above-ground (open) laying, heat pipes are laid on brackets along the walls of buildings, on concrete, reinforced concrete and metal supports. When passing heat pipelines through railways and water barriers, bridge structures are used. Heat pipelines laid under the bed of a river or canal, along the slopes and bottom of the ravine, are bent in accordance with the terrain. Such structures are called siphons. When laying under the riverbed, heat pipelines are enclosed in steel pipes (cases). Against the ascent, the pipes are held by weights. In this way, other types of underground networks (water supply, gas pipeline and sewerage) are also built when they cross rivers, ravines and other similar obstacles.

Assembly of steel pipes large diameters into links using a pipe-laying crane. Prior to the start of pipe assembly, pipes are brought into the links and laid out along a pre-marked axis; clean the ends of the pipes from contamination and straighten the deformed edges.

Steel pipes are assembled into links in the following sequence: the beds are laid and aligned, the pipes are laid on the beds using a pipe-laying crane; clean and prepare pipe edges for welding; center the joints with a centralizer, supporting the pipes with a pipe-laying crane during the tacking of the joint by electric welding; pipe joints are welded with the pipe link turning; the beds are removed and the assembled link is installed on the inventory linings.

Laying and alignment of beds. Pipelayers, pulling the tape measure along the axis of the layout of the links, mark on it the places for laying the beds. Then they bring the beds and lay them out according to the markings, while the middle of the beds should coincide with the axis of the layout. At the ends of the extreme beds, four metal pins are hammered and a twine is pulled between the extreme beds at the level of the top of the beds. Focusing on this level, intermediate beds are installed, cutting off or knocking out the soil under them with shovels.

Laying pipes on the bed. Having marked the middle of the pipe with a tape measure, the pipe-laying crane is installed so that its boom is above the center of gravity of the pipe. The pipe is slinged, and the crane operator lifts it by 20-30 cm. After making sure that the slinging is reliable and correct, the crane operator lifts the pipe to a height of 1 m and, at the command of the pipelayer, lays the pipe on the bed. Pipelayers, standing at both ends of the pipe, keep it from turning.

Cleaning and preparation of pipe edges for welding. When loading, transporting or unloading, ellipticity, dents, etc. may form at the ends of the pipes. If necessary, the ends of the pipes should be straightened. Curvature of the ends is straightened with screw jacks or manually by blows of a sledgehammer with preheating of the pipe at the place of straightening.

In the event that the deformed ends cannot be straightened, they are cut off by gas cutting, followed by cleaning the edges.

Using chisels and hammers, pipelayers clean the edges of pipes from dirt and ice. Electric grinders, files, reversible angular pneumatic brushes clean the edges to a metallic sheen for a length of at least 10 mm from the outside and from the inside.

Centering the joint and supporting pipes when tacking the joint. The driver sets the pipe-laying crane opposite the middle of the pipe and lowers the towel sling. The pipelayer slings the pipe and gives the command to lift it by 0.5 m and move it to the docking point. After moving the pipe, the workers lay it on the beds, visually center the joint, straighten and fix the pipe on the beds with wooden stakes. Then a centralizer is installed on the joint and the joint is fixed by turning the handle.

The electric welder, having checked the size of the gap between the ends of the pipes to be joined along the entire circumference with a universal template and making sure that the size of the gap corresponds to the norm, welds the joint.

If, when checking with a template, the gap between the ends of the pipes does not meet the regulatory requirements, the pipelayers loosen the centralizer, the crane operator changes the gap with the movement of the boom, while the pipelayers help him with crowbars. After obtaining the required gap, the position of the pipe is finally fixed with wooden wedges, the centralizer lever is tightened to failure, and then the joint is seized by welding. After tacking the joint, the pipelayers remove the centralizer.

Turning the link when welding pipes. After applying a seam to a quarter of the circumference of the pipe on each side, the pipelayers turn the link, fixing it with wooden wedges on the beds at the joint.

Installation and welding of mobile supports. Movable supports perceive the load from the weight of the heat pipe, in addition, ensure the movement of the pipeline in the axial direction, which occurs due to a change in its length with a change in temperature. Factory-made movable supports are sliding, skid, roller, suspended. Of the listed designs of movable bearings, sliding bearings are the most widely used.

Sliding supports can be low and high, normal length and shortened. The type of support is chosen depending on the thickness of the thermal insulation and the distance between the supports. Low (linings) and high supports protect pipes from abrasion when moving heat pipes. In addition, high supports protect the thermal insulation from contact with the base of the channel.

Sliding supports are installed on the support stones with some displacement towards the fixed support. When starting hot water, the pipeline will heat up and lengthen somewhat; the sliding support welded to the pipeline will shift towards the compensator and take up a working position on the support stone. If the sliding support is installed on the support stone without mounting offset, then it can come off the support stone during the operation of the heat pipeline. The sliding support moves along a metal lining, concreted into the support stone and protruding above its upper plane.

The distance between the sliding supports depends on the distance between the supporting stones, which in turn is taken depending on the nominal diameter of the pipes.

It is not allowed to weld sliding supports in places of welded joints. The support must be welded without lateral displacements in relation to the vertical axis of the pipeline.

Having marked the installation sites of the supports on the pipes, they are adjusted in place, grabbed and welded. Sliding supports are welded before pressure testing of the pipeline, since it is not allowed to perform welding work on a pipeline that has passed a hydraulic or pneumatic test for density and strength.

Installation of stuffing box compensators. Gland compensators perceive axial temperature deformations of pipelines of heating networks and thereby protect the pipeline and fittings from destructive stresses.

Gland compensators are made one-sided and two-sided. The compensating capacity of a double-sided compensator is twice that of a single-sided compensator.

The compensator is connected to the main pipeline by welding.

The compensator is installed in the extended position to the full length of the stroke, which depends on the compensating capacity, with a gap between the body thrust ring and the safety ring on the sleeve. The gap compensates for the change in the length of the pipeline when the temperature of the pipes drops after the compensator is installed (due to a decrease in the outside air temperature).

When installing the compensator, the stuffing box seals (gland) should be carefully stuffed, since the replacement of the stuffing during operation leads to a shutdown of the heating networks. The joints of the stuffing box rings must be displaced relative to each other, the seams of the stuffing box compensators must be even, and the craters must be welded.

Flange installation. Pipe fittings and line equipment are connected to the pipeline by welding or by flanges tightened with bolts, studs and nuts. With a conditional internal pressure in the pipeline up to 40 kgf / cm2 (4 MPa), bolts are used, at 40 kgf / cm2 or more, studs are used. The density of the flange connection depends on the accuracy of the surface treatment of the flanges, the quality of the bolts and the uniformity of their tightening. The flanges must be parallel to one another.

Flanges are welded perpendicular to the axes of the nozzles. The misalignment should not exceed 1 mm per 100 mm of the outer diameter of the flange (but not more than 3 mm). After fitting the flanges, two or three bolts are installed in place to align the gasket, then the remaining bolts are mounted, nuts are screwed onto them and the flange connection is tightened. To avoid distortion, the nuts are tightened gradually in a crosswise manner.

The diameter of the bolts must match the diameter of the holes of the flanges to be connected.. The bolt heads are located on one side of the connection. Flanged bolts may protrude above the nut by at least three threads and by no more than half the bolt diameter. It is necessary that the inner diameter of the gasket matches the inner diameter of the pipe with a tolerance of 3 mm, and its outside diameter must be not less than the diameter of the connecting ledge and not more than the diameter of the circle tangent to the bolts.

For a tighter fixing of the gasket, sometimes a protrusion is made on one of the flanges to be connected, and a depression on the other. The protrusion enters the cavity, and thus the gasket is securely fastened between the flanges. For the same purpose, concentrically located recesses - risks are applied to the mirror of the flanges.

When installing pipe fittings, for example gate valves, excessive tightening of the flanges with bolts should not be allowed, since the density and strength of the flange connection is reduced.

Stretching U-shaped compensators. To increase the compensating ability, U-shaped expansion joints are stretched. The stretching value specified in the project should be equal to half the elongation of the compensated section. The compensator is stretched only after fixed supports are installed on its two sides; thus, when the expansion joint is stretched, the pipeline remains motionless at the points of its welding to the supports. Only one joint remains unwelded - in the place of expansion joint stretching.

The compensator is stretched with the help of corner ties, jacks, hoists, etc.. At an equal distance along the circumference of the pipe of the U-shaped compensator, four plates are welded, and four plates are welded to the previously laid pipe. The distance between the plates must not exceed the length of the tie bolts. Coupling bolts are inserted into the hole of the plates and, by screwing the nuts, the compensator is stretched, bringing the edges of the pipes together to the gap required for welding. The joints are seized by electric welding, the plates are cut off with a gas cutter and the joint is welded.

Installation of heating network nodes. The pipelayer cleans the ends of pipes and pipes from rust and dirt with a steel brush or file. Then, using a crane, the unit is fed into the heating network chamber, where it is installed in the design position. After that, the edges are adjusted and trimmed and the joints are centered with an external centralizer. The joints are welded, the centralizer is transferred to the next work.

Calculation of stretching expansion joints of thermal networks. Calculation of pre-stretching of the compensator during installation

The following restrictions were taken into account:

Application area

Flexible expansion joints are used

1. GENERAL PROVISIONS

2. EARTHWORKS

3. CONSTRUCTIONS AND INSTALLATION OF BUILDING STRUCTURES

4. PIPING INSTALLATION

5. ASSEMBLY, WELDING AND QUALITY CONTROL OF WELD JOINTS

6. THERMAL INSULATION OF PIPING

7. TRANSITIONS OF HEAT NETWORKS THROUGH DRIVERS AND ROADS

8. TESTING AND FLUSHING (BLOWING) OF PIPING

9. ENVIRONMENTAL PROTECTION

Annex 1. ACT ON STRETCHING OF COMPENSATORS

Appendix 2. ACT ON TESTING PIPELINES FOR STRENGTH AND TIGHTNESS

Appendix 3. ACT ON FLUSHING (BLOWING) OF PIPELINES

1. General Provisions

2. Earthworks

3. Structures and installation of building structures

4. Installation of pipelines

5. Assembly, welding and quality control of welded joints

General provisions

Manufacturing jobs

Quality control

6. Thermal insulation of pipelines

7. Transitions of heating networks through driveways and roads

8. Testing and flushing (purging) of pipelines

General provisions

Hydraulic tests

Pneumatic tests

9. Environmental protection

Act about stretching compensators

Commission decision

Act on testing pipelines for strength and tightness

Commission decision

Act on flushing (purging) pipelines

Commission decision

Act
about stretching compensators

Act
on testing pipelines for strength and tightness

Act
on flushing (purging) pipelines