Hydraulic testing of thermal networks. Operational tests of heat networks

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Hydraulic test pipelines.


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

In cases where, when testing heat pipelines without equipment and fittings, there is a pressure drop across the instruments, it means that the existing welds are loose (naturally, if there are no fistulas, cracks, etc. in the pipes themselves). Pressure drop when testing pipelines with installed equipment and fittings, possibly indicates that in addition to the joints, gland seals or flange connections are also made with defects.

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

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

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

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

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

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

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

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

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

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Tests of thermal networks are starting and operational. Start-up tests are carried out after the construction of new networks or overhaul. They are intended to determine the suitability of the structure for operation. During operation, sludge accumulates in pipes and equipment, pipelines corrode, protective properties thermal insulation change. The allowable change in the various characteristics of the structure is periodically checked by performance tests. Start-up and operational tests are divided into pressure testing, hydraulic and thermal tests and tests for the maximum coolant temperature.

Crimping designed to determine the density and mechanical strength pipelines, fittings and equipment. Starting pressure testing of channelless networks and in impassable channels is carried out in two stages: preliminary and final. Preliminary pressure testing is carried out as the work is completed in short sections before the installation of stuffing box compensators, valves on the pipelines and before closing the channels or backfilling the trenches. The purpose of pressure testing is to check the strength of welding under a test overpressure of 1.6 MPa during the time necessary for inspection and tapping of the joints. Tapping is carried out with hammers weighing 1.5 kg on a handle 500 mm long, blows are applied on both sides of the seam at a distance of about 150 mm from the joint.

Final pressure testing is done after completion of all work and installation of all equipment elements on pipelines, but before thermal insulation is applied. When installing networks from seamless pipes, it is allowed thermal insulation before the test, but leaving the welded joints free of insulation. The overpressure pressure is brought to 1.25 R slave (R slave - working pressure), but not less than 1.6 MPa in the supply pipelines and 1.2 MPa in the return pipelines. The duration of crimping is determined by the time required to inspect the networks.

Pressure testing of equipment of substations, heating points, together with local systems, is carried out in two steps. Equipment and pipelines disconnected from the networks are filled with water from the city water supply, required pressure testing is created by the pressure of pressure testing pumps with a manual or mechanical drive. Initially, the system is pressurized with working pressure to check the tightness of welded and flanged joints of equipment, fittings and pipelines. Then overpressure is brought to 1.25 of the working one, but not lower than the norms established for each type of equipment necessary for strength testing. The duration of the test of heat points and pipelines extending from them is taken at least 10 minutes.


The results of testing networks and heating points at each stage are considered satisfactory if during their implementation a pressure drop above the established limits is not detected, and there are no breaks, water leaks and fogging in welds, flange joints and fittings. If breaks and other damage are found, the water is drained (from the networks in no more than 1 hour); defective seams are cut down and digested; leaks are eliminated by tightening the bolts, changing the packing. Then the pressing is repeated. Operating heating network are pressed annually at the end heating season to detect defects and after overhaul.

Hydraulic tests are designed to determine the actual hydraulic characteristics of the new network and equipment of points or changes in these characteristics during operation. During hydraulic tests, the pressure, flow rate and temperature of the coolant are simultaneously measured at characteristic points (places of change in diameters, water flow rates, network jumpers) of the network. At control points, exemplary pressure gauges are installed, mercury thermometers with a division value of 1°C and normal measuring diaphragms. The tests are carried out with the heat points turned off at maximum and reduced to 80% of maximum expenses water. Water circulation in networks and branches is ensured by the inclusion of end jumpers.

The pressure loss in the investigated sections of the supply and return pipelines is calculated by the formula:

where P1, P2- pressure gauge readings at the beginning and end of the section, Pa;

z 1 , z 2- geodetic marks at the points of location of pressure gauges, m;

is the heat carrier density at the corresponding temperature, kg/m 3 .

According to the pressure measurements in the supply and return pipelines, a real piezometric graph is built, and the estimated pressure graph is determined from the water flow rates in the sections. By comparison, the deviations of the actual and calculated piezometric graphs are established.

Thermal testing carried out in order to determine actual losses heat in the networks and comparing them with the calculated and normative values. The need for thermal testing is dictated by the natural destruction of thermal insulation, its replacement in certain areas, as well as structural changes. Tests are carried out at the end of the heating season, when the entire structure of the heat pipeline and the adjacent soil are warmed up fairly evenly. Before testing, the destroyed insulation is restored, the chambers and channels are drained, and the operation is checked. drainage devices, heat points consumers are turned off, water is circulated through jumpers.

During the tests, the flow rates and temperatures of the coolant are measured at the beginning and end of the investigated section of the supply and return pipelines. A stable circulation mode is established, in which several readings are taken after 10 minutes.

The actual specific heat loss is determined by the formulas

; (14.3)

, (14.4)

where q f1 , q f2- actual specific heat losses in the supply and return pipelines, kW/m; G 1 , G p–. average consumption of network water, respectively, in the supply pipeline and make-up water, kg / h; τ 11 , τ 12- average water temperatures at the beginning and end of the supply pipeline, °С; τ 21 , τ 22- the same, the return pipeline; l- section length, m.

By comparing the actual heat losses with the calculated ones, the quality of the insulation is established. To compare with the standard losses, the actual heat losses are recalculated according to the average annual water temperatures in the supply and return pipelines and the average annual temperature environment. Heat loss steam pipelines are determined by the change in enthalpy, steam humidity and the amount of condensate. Thermal and hydraulic tests of networks are carried out after 3-4 years.

Tests for maximum coolant temperature carried out in order to control the reliability of the structure, the operation of compensators, the displacement of supports, to determine the actual stresses and deformations of the most loaded network elements. Tests are carried out every two years at the end of the heating season with disconnected consumers with the circulation of the coolant through the end bridges.

During the test period, the temperature of the coolant rises at a rate of 30 ° C per hour, at the end points of the network Maximum temperature held for at least 30 minutes.

As the pipelines heat up, at certain time intervals, the movements of fixed points on the pipes, U-shaped arms and sleeves of stuffing box expansion joints are measured. The actual displacements of the network elements are compared with the calculated ones and the actual stresses at the characteristic points are established from them. If the difference between the calculated and actual elongations of pipelines exceeds 25% of the calculated elongation, then searches should be made for places of pipe pinching, subsidence or shear fixed supports and other reasons for this difference.

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4.2. Rules for testing pipelines of heating networks during their acceptance into operation 4.2.1. Before commissioning, all newly installed pipelines of heating networks must be subjected to a hydraulic test in order to check the strength and tightness of pipelines and their elements, including all welded and other connections. The following are subject to hydraulic testing: a) all elements and details of pipelines; their hydraulic test is not mandatory if they have been subjected to 100% ultrasonic testing or other equivalent non-destructive testing method; b) blocks of pipelines; their hydraulic test is not mandatory if all their constituent elements were tested in accordance with clause 4.2.1, a, and all welded joints made during their manufacture and installation were checked by non-destructive flaw detection methods (ultrasound or radiography along the entire length); c) pipelines of all categories with all elements and their fittings after installation is completed. 4.2.2. It is allowed to conduct a hydraulic test of individual and prefabricated elements together with the pipeline, if during the manufacture or installation it is impossible to test them separately from the pipeline. 4.2.3. Hydraulic tests of underground pipelines laid in impassable channels and trenches should be carried out twice (preliminary and final). Testing of pipelines accessible for inspection during operation (laid above ground and in through channels) can be carried out once after installation is completed. 4.2.4. Preliminary hydraulic testing of pipelines should be carried out in separate sections after they are welded and laid on permanent supports before installing equipment (stuffing box, bellows compensators, valves) on them and blocking channels and backfilling pipelines without channel laying and channels. Supply and return pipelines shall be tested separately. 4.2.5. Minimum value test pressure during hydraulic testing of pipelines, their blocks and individual elements should be 1.25 working pressure. The working pressure for pipelines of heating networks must be taken in accordance with the requirements. Valves and fittings of pipelines must be subjected to a hydraulic test pressure test in accordance with. 4.2.6. The maximum value of the test pressure is set by the strength calculation according to the NTD, agreed with the Gosgortekhnadzor of Russia. The test pressure value is chosen by the design organization (manufacturer) within the limits between the minimum and maximum values. 4.2.7. The hydraulic test must be carried out in next order: disconnect the tested section of the pipeline from the existing networks; at the highest point of the section of the pipeline under test (after filling it with water and venting), set the test pressure; the pressure in the pipeline should be increased smoothly; the rate of pressure rise must be specified in the NTD for the manufacture of the pipeline; withstand the pipeline under test pressure for at least 10 minutes, then gradually reduce the pressure to the working one and at this pressure perform a thorough inspection of the pipeline along its entire length. 4.2.8. With a significant difference in geodetic windings on the test section, the value is maximum allowable pressure at its lowest point must be agreed with the design organization to ensure the strength of pipelines and the stability of fixed supports. Otherwise, the test must be carried out in separate sections. 4.2.9. For hydraulic testing, water with a temperature not lower than plus 5°C and not higher than plus 40°C should be used. Hydraulic testing of pipelines should be carried out at a positive ambient temperature. 4.2.10. Pressure measurement should be carried out using two pressure gauges, one of which should be a control one. The pressure should rise and fall gradually. When testing pipelines, spring pressure gauges certified by the territorial bodies of the State Standard of Russia should be used. The use of pressure gauges with expired calibration dates is not allowed. Spring pressure gauges must have an accuracy class of at least 1.5, a body diameter of at least 150 mm and a scale for a nominal pressure of about 4/3 of the measured one. 4.2.11. The pipeline and its elements are considered to have passed the hydraulic test if no leaks, sweating in welded joints and in the base metal, visible residual deformations, cracks and signs of rupture are found. 4.2.12. Hydraulic testing of valves should be carried out before they are installed on the pipeline. Tests are divided into two main types; metal strength and density tests; tightness tests of movable and fixed connectors of connections (stuffing boxes, locking devices, etc.). Hydraulic pressure testing of fittings is carried out by test pressure in accordance with. 4.2.13. The final hydraulic test should be carried out after completion of the construction installation work, installation of all equipment (gate valves, compensators, etc.). The minimum value of the test pressure shall be 1.25 times the operating pressure (see point 4.2.5). All sectional valves and valves on the branches of the tested heating network must be open. The exposure time of the pipeline and its elements under test pressure must be at least 10 minutes, after which the pressure is gradually reduced to the working one and a thorough inspection of the pipeline along its entire length is carried out. Supply and return pipelines are tested separately. The test results are considered satisfactory if during the test there was no decrease in pressure on the pressure gauge and no signs of rupture, leakage or fogging in the welds, leaks or fogging in the valve bodies and glands, in flanged joints, etc.

5. START-UP OF HEAT NETWORKS

5.1. General provisions 5.1.1. For all pipelines that are subject to, by the enterprises-owners of pipelines on the basis of the documentation submitted assembly organizations and manufacturing plants, passports of the established form must be drawn up (see Appendix 15). 5.1.2. Pipelines of category III with a nominal bore of more than 100 mm, as well as pipelines of category IV with a nominal bore of more than 100 mm, located within the buildings of thermal power plants and boiler houses, must be registered before being put into operation with the Gosgortekhnadzor of Russia. Other pipelines that are subject to registration are subject to registration at the enterprise (organization) that owns the pipelines. The procedure for registering pipelines with the bodies of the Gosgortekhnadzor of Russia and the necessary technical documentation shown in . (Changed edition, Rev. No. 1) 5.1.3. The start-up of heating networks is carried out by the start-up team headed by the head of the start-up team. The launch must be carried out according to the work program approved by the chief engineer of the OETS. For newly built main heat networks, extending directly from the collectors of the heat source, the program must be agreed with the chief engineer of the heat source. Working programm before launch, it must be transferred to: the head of the launch brigade; OETS dispatcher on duty; head of the heat source shift; duty engineer of the operational area of ​​the OETS. The heat network start-up program should include: a diagram of the pumping and heating plant of the heat energy source and its operation mode during the network start-up in separate, clearly delimited in time, stages; operational scheme of the heat network during start-up; sequence and order of start-up of each individual highway or section; the filling time of each line, taking into account its volume and filling rate; the calculated static pressure of each filled line and the effect of this pressure on adjacent pipelines of the network; the composition of the launch team, the arrangement and duties of each performer during each stage of the launch; organization and means of communication of the head of the launch team with the duty dispatcher of the OETS, the duty engineer of the operational area, the duty engineer of the heat source, as well as between individual members of the team. 5.1.4. Before start-up, a thorough inspection of the heating network should be carried out, the serviceability of all equipment should be checked, acts of acceptance, tests for strength and density, flushing of newly built and repaired sections of the network should be reviewed. All defects in pipelines, fittings, compensators, supports, drainage and pumping devices, air vents, instrumentation, as well as hatches, ladders, brackets and others, identified as a result of inspection of the network, must be eliminated before the start-up. 5.1.5. Before launch, the head of the launch team must personally instruct all personnel involved in the launch, give each member of the launch team specific instructions in accordance with the place of work and possible changes in the regime, as well as instructions on safety rules for all launch operations. 5.1.6. The head of the start-up team, after making sure that all the equipment is in good condition, informs the duty engineer of the operational area about the readiness, and he, in turn, reports to the OETS dispatcher on duty about the readiness of the heating system for start-up. After receiving a message from the duty engineer of the operational area and the duty engineer of the thermal energy source about the readiness of the equipment for start-up, the OETS dispatcher on duty allows the duty engineer of the thermal energy source and the duty engineer of the operational area to start the network in accordance with the program. Regardless of the approved program and schedule, the start-up of the heating network without the permission of the OETS dispatcher on duty, given immediately before the start-up, is not allowed. 5.1.7. The head of the launch team must monitor the progress of filling, heating and drainage of pipelines, the condition of fittings, compensators and other equipment. In the event of any malfunctions or damage to the equipment, the head of the launch team must take measures to immediately eliminate these malfunctions, and if it is impossible to eliminate them or serious damage occurs (rupture of joints, destruction of reinforcement, failure of a fixed support, etc.) - immediately issue a stop order. The head of the launch team must report on the progress of launch operations to the duty engineer of the operational area, and in exceptional cases, directly to the duty dispatcher of the OETS. 5.1.8. The duty dispatcher of the OETS and the duty engineer of the operational area must record in operational logs the time of individual launch operations, instrument readings, the condition of the heating network equipment, as well as all malfunctions and deviations from the normal launch program. 5.1.9. Upon completion of the launch, the head of the launch team reports this to the duty engineer of the operational area, the head of the operational area of ​​the OE and makes an entry in the operational log of the OETS operational area. The duty engineer of the operational area immediately reports to the OETS dispatcher on duty about the completion of start-up operations. 5.2. Start-up of a water heating network 5.2.1. Filling the heating network with water 5.2.1.1. Filling the heating network with water and establishing a circulation regime should, as a rule, be carried out before the start of heating period at positive outside temperatures. 5.2.1.2. All pipelines of the heating network, regardless of whether they are in operation or in reserve, must be filled with chemically treated, deaerated water. Pipelines are emptied only for the period of repair, after which the pipelines, after a hydraulic test for strength and density and flushing, must be immediately filled with chemically purified deaerated water. 5.2.1.3. Pipelines of the heating network should be filled with water at a temperature not exceeding 70 ° C . Filling pipelines with water directly from deaerator tanks atmospheric type in the absence of coolers, make-up should be carried out either after the water in them has cooled to 70 ° C, or by mixing water and return pipelines of previously filled networks with deaerated water so that the total temperature of the mixture is not higher than 70 ° C. 5.2.1.4. Pipelines should be filled with water at a pressure not exceeding static pressure the filled part of the heating network by more than 0.2 MPa (2 kgf / cm 2). To avoid water hammer and better removal air from pipelines, the maximum hourly water consumption (G in m 3 / h) when filling pipelines of a heating network with a nominal diameter (D y mm) should not exceed:
The filling rate of the heating network should be linked to the performance of the recharge source. 5.2.1.5. Filling with water of the main main pipelines of the heating network should be carried out in the following order: a) on the section of the pipeline being filled, close all drainage devices and valves on the jumpers between the supply and return pipelines, turn off all branches and subscriber inputs, open all air vents of the filled part of the network and sectional valves, except for the head ones; b) on the return pipeline of the area being filled, open the bypass of the head valve, and then partially open the valve itself and fill the pipeline. For the entire filling time, the degree of opening of the valves is set and changed only at the direction and with the permission of the OETS dispatcher; c) as the network fills up and the air displacement stops, close the air vents; d) upon completion of filling the return pipeline, open the end jumper between the supply and return pipelines and start filling the supply pipeline with water in the same order as the return pipeline; e) the filling of the pipeline is considered complete when the air outlet from all air valves stops and those watching the air vents report to the head of the launch team about their closure. The completion of filling is characterized by an increase in pressure in the collector of the heat network to the value of static pressure or to the pressure in the make-up pipeline. After completion of filling, open the head valve on the return pipeline completely; f) after filling the pipelines, it is necessary to open the air valves several times within 2-3 hours to ensure the final removal of air. Make-up pumps must be in operation to maintain the static pressure of the filled network. 5.2.1.6. filling distribution networks should be made after filling the main pipelines with water, and branches to consumers - after filling the distribution networks. Distribution networks and branches are filled in the same way as the main main pipelines. 5.2.1.7. Heating networks with pumping (pumping or mixing) stations should be filled through bypass pipelines. 5.2.1.8. The control valves installed on the pipelines must be manually opened and disconnected from the measuring and control devices during the filling period. 5.2.2. Establishment of the circulation regime 5.2.2.1. Establishment of the circulation regime in main pipelines should be carried out through end jumpers with open sectional valves and disconnected branches and heat consumption systems. 5.2.2.2. The inclusion of a water heating installation of a source of thermal energy, if it did not work before the start of the switched on line, should be carried out during the establishment of the circulation mode. 5.2.2.3. The establishment of the circulation regime in the main should be carried out in the following order: a) open the valves at the inlet and outlet of network water at network water heaters; if there is a bypass line for water heaters, open the valves on this line (in this case, the valves at the water heaters remain closed); b) open the valves on the suction pipes of the network pumps, while the valves on the discharge pipes remain closed; c) include one network pump; d) first slowly open the bypass valve on the discharge pipe of the network pump, and then the valve and establish circulation; e) turn on the steam supply to the network water heaters and start heating the network water at a rate of not more than 30 ° C / h. The establishment of circulation should be done very slowly, observing the requirements set out in paragraph 5.2.2.4; f) after the circulation mode is established by the make-up regulator, set the design pressure in the return manifold of the heat source according to the piezometric graph in the operating mode. 5.2.2.4. The establishment of the circulation mode in the line, which is switched on when the water heating installation is running, should be carried out by sequentially and slowly opening the head valves on the return (first of all) and supply pipelines. In this case, it is necessary to follow the pressure gauges installed on the supply and return manifolds source of thermal energy and on the return pipeline of the switched on line to the valve (along the flow of water), so that pressure fluctuations in the return and supply manifolds do not exceed the norms established by the PTE, and the pressure value in the return pipeline of the started line does not exceed the calculated value. 5.2.2.5. After establishing the circulation mode in pipelines with pressure regulators, they should be adjusted to ensure the specified pressures in the network. 5.2.2.6. The establishment of the circulation mode in the branches from the main line should be carried out through the end jumpers on these branches by alternately and slowly opening the head valves of the branches, first on the return, and then on the supply pipelines. 5.2.2.7. The establishment of the circulation regime in the branches to heat consumption systems equipped with elevators should be carried out by agreement and with the participation of consumers through the mixing line of the elevator. At the same time, the heating systems after the elevator and the branches to the ventilation and hot water supply systems must be tightly turned off by valves. The establishment of circulation in the branches to heat consumption systems connected without elevators or with pumps should be carried out through these systems with the inclusion of the latter in operation, which should be carried out by agreement and with the participation of consumers. Gate valves at heat points of heat consumption systems that are not subject to inclusion when the circulation mode is established in the pipelines of the heat network must be tightly closed, and the drain valves after them must be in open state to avoid flooding and pressure build-up in these systems. 5.2.2.8. When starting pumps at pumping stations, it is necessary to: open the valves separating the pumping station from the network; open the valve on the suction side of the pump; the valve on its discharge side remains closed; turn on the electric motor of the pumping unit; smoothly open the valve on the pump discharge pipe, and if there is a bypass at the valve, open the bypass first, and then the valve (in this case, observe the ammeter reading); close the valve on the bypass pipeline through which the network was filled: alternately turn on required amount pumps to achieve the specified hydraulic mode; in this case, the start-up of each subsequent pump is carried out similarly to the start-up of the first pump; set standby pump to position automatic start reserve (AVR); adjust the installed pressure and protection regulators in accordance with the settings chart approved by the chief engineer of the OETS; after the establishment of the circulation mode, before turning on the consumers, test (test) the means automatic regulation and protection as required. Start pumping stations on the return pipelines, it is carried out before the heat consumption systems are turned on, and on the supply pipes, in the process of turning on the heat consumption systems as the heat load increases. 5.2.3. Features of starting a water heating network at negative outdoor temperatures 5.2.3.1. To start heating networks at negative outdoor temperatures after a long emergency shutdown, overhaul or when starting up newly built mains, it is necessary to insert additional downcomers into the supply and return pipelines of the filled network with a pipe diameter of 300 mm or more at a distance of no more than 400 m from one another ; discharge of drained water must be taken outside the chambers. 5.2.3.2. Pipelines should be filled with water at a temperature of 50-60°C in separate sections separated by sectional valves simultaneously along the supply and return pipelines. In the case of limited make-up water supply, the return pipeline should be filled first, and then the supply pipeline should be filled through the jumper in front of the sectional valves at the end of the section. If the water heating plant of the heat source is not operating, water is supplied through the bypasses of the head valves to the supply and return pipelines. If the water heating plant is in operation, water is supplied through the bypass of the head valve to the return pipeline and through a specially cut jumper after the head valves to the supply pipeline, while the head valve (and bypass) on the supply pipeline must be tightly closed. 5.2.3.3. The filling of pipelines with water and the establishment of a circulation mode in the heating network with an idle water heating installation should be carried out in the following order: a) before filling the pipelines, all drain devices and air vents should be opened, as well as valves on the jumper between the supply and return pipelines in front of the sectional valves; air vents must be closed after the air has stopped flowing through them, and drains - after the temperature of the drained water exceeds 30 ° C; b) after filling the pipelines of the head sectioned section and closing all air vents and drainage devices, turn on the network pump and slowly open the valve on the pump discharge pipe (with the valve on the suction side of the pump open) create circulation in this section through the jumper in front of the sectional valves; immediately after the creation of circulation, supply steam to the network water heater to replenish heat losses in the pipeline sections being filled;

Thermal network testing. The constructed pipelines of heating networks before putting them into operation are tested for strength and density by water pressure (hydraulic test) or air (pneumatic test).

During the test, the tightness and tightness of welds, pipes, flange connections, fittings and linear equipment (stuffing expansion joints, mud collectors, etc.) are checked. The heat pipe is tested twice: preliminary and final.

During the preliminary test check the strength and tightness of the welds and the walls of the pipeline before installing fittings and linear equipment. If the heat pipeline is made of pipes with a longitudinal or spiral seam, then the test is carried out before the installation of thermal insulation on the pipeline.

If the heat pipeline is made of seamless seamless pipes, then during testing it can be insulated, while only welded joints remain open. Before the preliminary test, the heat pipe must not be closed building structures and fall asleep.

The length of the section during the preliminary test is determined depending on the local conditions, the accepted organization of work, the availability of test facilities (hydraulic presses, piston pumps), the timing of construction in individual sections, the capacity of the water source for filling the heat pipeline, the availability of filling facilities, terrain, etc.

At the final test, the construction of the heat pipeline must be fully completed in accordance with the project. During testing, they check the junctions of individual sections (if the heat pipeline was previously tested in parts), welds, fittings and linear equipment, the tightness and strength of flange joints, housings of linear equipment, etc.

The hydraulic test is performed in the following sequence: mount the test rig; clean the heat pipe from the inside from scale, soil and other objects; install plugs, pressure gauges and taps; attach plumbing and press; fill the pipeline with water set pressure; inspect the pipeline and mark defective places; eliminate the detected defects; re-test; disconnect the water supply and drain the water from the heat pipe; remove plugs and gauges.

To force air out of the pipes, the water supply is brought to the lowest point of the pipeline, all air valves are opened, and the drain valves are closed. Near the air taps should be on duty, who block them when water appears.

The spring pressure gauges used in the test must be checked and sealed by the organizations of the State Standard; plugs must match technical requirements. It is not allowed to use valves to disconnect the test section from existing networks.

The test pressure is maintained for 5 min.. The manometer checks for a drop in pressure, after which the pressure is reduced to the working one. At operating pressure, the pipeline is inspected and the welds are tapped with a hammer with a handle no longer than 0.5 m. The weight of the hammer should not exceed 1.5 kg. Blows are applied not to the seam, but to the pipe (no closer than 100 mm from the seam).

The test results are considered satisfactory if there is no pressure drop on the gauge and no leakage or sweating of the joints is detected.

At the final hydraulic test with fittings and equipment installed, the test pressure is maintained for 15 minutes. Then, welded and flanged joints, fittings and line equipment are inspected, and then the pressure is reduced to working pressure. If, in this case, the pressure drop during 2 hours does not exceed 10%, then the heat pipeline is considered to have passed the test.

AT winter time hydraulic tests of heat pipelines should be carried out in short sections, while for testing it is necessary to use water heated to a temperature of 60 ° C. In addition, lowering devices are installed that ensure that water is drained from the pipes for 1 hour.

Pneumatic testing of heat pipes carried out only in cases where a hydraulic test cannot be applied. The length of the test section is assumed to be no more than 1000 m.

Pneumatic testing is carried out in the following sequence: clean and purge the pipeline; install plugs and pressure gauges; attach a compressor to the pipeline; fill the pipeline with air to a predetermined pressure; prepare a soap solution; inspect the pipeline, smearing the joints with soapy water, and note the defective places; eliminate the detected defects; second test the pipeline; disconnect the compressor and bleed air from the pipeline; remove plugs and gauges.

Leaks in the pipeline are determined in several ways.: by the sound of escaping air; bubbles that form at the leak when joints and other welded joints are covered with soapy water; by smell, if ammonia, ethyl and other gases with a pungent odor are added to the air supplied from the compressor to the pipeline. The most common method is using a soap solution, which includes water -1 l and laundry soap - 100 g. If during the test the outside temperature is below 0 ° C, then in soapy water water is partially (up to 60%) replaced with alcohol or other non-freezing liquid that dissolves soap.

During preliminary testing of the pipeline kept under test pressure for 30 minutes, then the pressure is reduced to 3 kgf/cm2 and the pipeline is inspected. If during the inspection no leaks, defects in welds, violation of the integrity of the pipeline, as well as no shear or deformation of the structures of fixed supports are found, then the pipeline is considered to have passed the preliminary pneumatic test.

Defects identified during inspection of the pipeline are eliminated after the excess pressure in it drops to zero.

During the final pneumatic test, the pressure in the pipeline is brought to the test pressure and maintained for 30 minutes. If the integrity of the pipeline is not violated, then the pressure is reduced to 0.5 kgf / cm2 and the pipeline is maintained at this pressure for 24 hours. Then a pressure of 3000 mm of water is set. Art. and note the start time of the test and the barometric pressure.

Hydropneumatic flushing is more efficient than hydraulic flushing. In this case, air is supplied by the compressor to the pipeline, the cross section of which is not completely filled with water. Turbulent water movement is created in the pipes, which contributes to good flushing.

The pipelines are washed until the water is completely clarified.

Flushing the pipeline. In the pipeline after installation may remain various kinds impurities: scale, stones, soil, etc. To remove them, the pipeline should be flushed with water (hydraulic flushing) or a mixture of water and air (hydropneumatic flushing).

The heat pipe is usually flushed twice: the first washing is rough, the second is finishing.

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Hydraulic testing of heating networks are needed to test pipelines, constituent elements, seams, for strength and their density. This is done due to the fact that over time, even with good maintenance, equipment can wear out and, as a result, fail. And to prevent emergencies, for the timely detection of defects that can cause an irreversible process, a number of activities are carried out, consisting of network testing and testing.

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One of which is hydraulic, required to identify:

  • actual consumption of water by consumers;
  • determination of pipeline hydraulic characteristics;
  • to find areas with increased hydraulic resistance;
  • testing for strength and tightness.

When is hydrotesting required?

  • At the end of the installation work of the pipeline, which was carried out due to the replacement of pipes or the assembly of a new section heating system before putting it to work.
  • In case of replacement or repair of the components of the heating network.
  • During the execution of scheduled maintenance of the network, which is carried out in order to start the heating system for the autumn and winter periods.

The cost of hydraulic testing of heating networks

What is used to measure the characteristics of the pipeline

When carrying out measures for measuring flow rates and pressures, devices are used that are metrologically certified:

  • One of them is a deformation manometer or pressure sensors, which have an accuracy class of at least 0.4. These instruments are used to measure pressure.
  • When measuring water flow, standard devices are used, which are installed on heat source and with the help of flow meters that are part of the accounting unit. In the absence of one of the listed devices, an ultrasonic flow meter is used, the sensors of which are attached. The value of its error should be no more than 2.5 percent.

Test steps

Activities consist of preparation, direct verification and analysis of indicators obtained as a result of tests.

  • The first stage is preparation. During this period, the initial data on the network are clarified and recorded, after which the measurement program is developed and agreed upon. At this stage, preparatory actions are also underway to create conditions for testing. This includes:
    • Before starting the process, you need to check whether all welding, installation, installation of gaskets in joints, tightening of these joints have been completed.
    • You also need to check whether all the equipment is in order, the presence and operability of the drain with air valves.
    • Connecting the hydraulic press to the water supply and to the pressure pipe pipeline. Performing a connection check.
    • Disconnecting the section of the pipeline where the test will be carried out from equipment that has not yet been fully installed or is already in use.
    • Installation of the necessary devices for testing.
  • The second stage is the verification under appropriate conditions. Tests must be carried out in compliance with all requirements regarding temperature regime environment. In case of violation, this can lead to inaccurate data received.
  • The necessary conditions:
    • The ambient temperature during the events should be above zero.
    • The temperature of the water used in the test must be between +5 and +40.
    • Provision of viewing platforms, with an above-ground location of the heating system.
    • Smoothness of pressure increase. It should be higher than the nominal by about 40%. To increase it, the use of compressed air is prohibited.
    • It is necessary to maintain the test section of the pipeline under test pressure for at least 15 minutes.
    • Upon completion, the entire area must be carefully examined and, if defects are found, the measures necessary to eliminate them must be taken.
  • And the last step, this is an analysis of the results obtained and the compilation of a table indicating all the parameters. If deviations from the norm are detected, measures are taken to eliminate them, such as:
    • Pipeline cleaning and flushing.
    • Pipeline relocation.
    • In case of serious problems, repairs and elimination of detected defects are carried out.

At the end of the measures to eliminate the causes due to which deviations occur, the tests must be carried out again.

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