How are hydraulic tests of heating mains carried out. Hydraulic tests What are the hydraulic tests of heating networks for?

General information

On the basis of the Rules for the technical operation of thermal power plants (approved by order of the Ministry of Energy of the Russian Federation of March 24, 2003 N 115), enterprises of heating networks during the operation of heating network systems must ensure the reliability of heat supply to consumers, the supply of heat carriers (water and steam) to it with a flow rate and parameters in accordance with with temperature control curve and pressure drop at the inlet.

During operation, all operating heating networks must be tested for strength and density to identify defects no later than two weeks after the end of the heating season.

Hydraulic tests of pipelines of water heating networks in order to check the strength and density should be carried out with test pressure with the results being entered into the report.

Test pressure - the overpressure at which a hydraulic test of thermal power plants and networks for strength and density should be carried out.

The minimum test pressure during hydraulic testing is 1.25 working pressure, but not less than 0.2 MPa (2 kgf / cm 2).

The maximum value of the test pressure is set by the strength calculation according to the normative and technical documentation agreed with the Gosgortekhnadzor of Russia. The value of the test pressure is chosen by the manufacturer (design organization) in the range between the minimum and maximum values.

Hydraulic tests are carried out by the person responsible for the safe operation of heating networks together with personnel approved for the operation of heating networks.

Hydraulic tests

When conducting hydraulic tests for the strength and density of heating networks, the equipment of heating networks (stuffing boxes, bellows expansion joints, etc.), as well as pipeline sections and connected heat-consuming power plants that are not involved in the tests, should be disconnected with plugs.

Strength and density tests are carried out in the following order:

disconnect the tested section of the pipeline from the existing networks;

at the highest point of the tested pipeline section (after filling it with water and bleeding air), set a test pressure (control by a pressure gauge);

the pressure in the pipeline should be increased smoothly;

the rate of pressure rise should be indicated in the normative and technical documentation (NTD) for the pipeline.

Tests for strength and density are carried out in compliance with the following basic requirements: pressure measurement during testing should be carried out using two certified spring pressure gauges (one - control) of class not less than 1.5 with a case diameter of not less than 160 mm. The pressure gauge should be selected so that the measured pressure value is within 2/3 of the scale of the device; test pressure must be provided at the highest point (mark) of the pipelines; the water temperature should be at least 5 ° С and not higher than 40 ° С; when filling with water, air must be completely removed from the pipelines; the test pressure must be maintained for at least 10 minutes and then reduced to working pressure; at operating pressure, a thorough inspection of the pipelines along their entire length is carried out.

The test results are considered satisfactory if during the test there was no drop in pressure and no signs of rupture, leakage or fogging in the welds, as well as leaks in the base metal, in the bodies and glands of valves, in flanged joints and other pipeline elements. In addition, there should be no signs of shear or deformation of pipelines and fixed supports.

An act of the established form is drawn up on the results of testing pipelines for strength and density.

The results of hydraulic tests of the pipeline for strength and tightness are considered satisfactory if during the tests there was no pressure drop, no signs of rupture, leakage or fogging in the welded seams, as well as leaks in the base metal, flange joints, fittings, expansion joints and other pipeline elements were found , there are no signs of shear or deformation of the pipeline and fixed supports.

There are 4 types of tests for heating networks:

1. Strength and tightness (crimping). Performed at the manufacturing stage before applying insulation. When used annually.
2. Design temperature... Carried out: in order to check the operation of compensators and fix their working position, to determine the integrity of fixed supports (1p. In 2 years). Tests are carried out during the manufacture of networks before applying insulation.
3. Hydraulic... They are carried out in order to determine: the actual water consumption of consumers, the actual hydraulic characteristics of the pipeline and the identification of areas with increased hydraulic resistance (once every 3-4 years).
4. Thermal tests... To determine the actual heat losses (once every 3-4 years). The tests are carried out according to the following dependence:

Q = cG (t 1 - t 2) £ Q norm = q l * l,

where q l is the heat loss of 1m of the pipeline, determined according to SNiP “Thermal insulation of pipelines and equipment”.

Heat loss is determined by the temperature at the end of the section.

Strength and tightness tests.

There are 2 types of tests:

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

Hydraulic tests.

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

Order of conduct:

1. Disconnect the test area with plugs. Replace stuffing box expansion joints with plugs or inserts. Open all bypass lines and valves if they cannot be replaced with plugs.
2. The test pressure is set = 1.25P slave, but not more than the operating pressure of the pipeline P at. Exposure 10 minutes.
3. The pressure is reduced to working pressure, while the inspection is carried out at this pressure. Leaks are monitored by: pressure drop on the pressure gauge, obvious leaks, characteristic noise, pipe fogging. At the same time, the position of the pipelines on the supports is monitored.

Pneumatic tests it is prohibited to carry out for: Overhead pipelines; When combined with laying with other communications.

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

Instruments: 2 pressure gauges, pressure source - compressor.

1. Filling at a rate of 0.3 MPa / hour.
2. Visual inspection at pressure P ≤ 0.3P is tested. , but not more than 0.3 MPa. R isp = 1.25R slave.
3. The pressure rises to P tested, but not more than 0.3 MPa. Exposure 30 min.
4. Decrease in pressure to P slave, inspection. Leaks are identified by signs: a decrease in pressure on manometers, noise, bubbling of soapy water.

Safety precautions:

• during the inspection, it is forbidden to go down into the trench;
• do not come under a jet of air.

Design temperature tests

Heating networks with d ≥100mm are tested. At the same time, there should be a design temperature in the supply pipeline and no more than 100 0 С in the return line. The design temperature is maintained for 30 minutes, while the increase and decrease in temperature should not be more than 30 0 С / hour. This type of test is carried out after pressure testing of the networks and elimination of gaps.

Tests for determination of heat and hydraulic losses

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

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

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

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

Content of the article

Why and when to carry out hydraulic tests?

Hydraulic testing is a type of non-destructive testing that is carried out to check the strength and tightness of pipeline systems. All operating equipment is subjected to them at different stages of operation.

In general, there are three cases in which tests must be carried out without fail, regardless of the purpose of the pipeline:

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

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

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

Features of hydraulic tests

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

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

This possibility should be ruled out at the initial stage.

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

While the test is in progress, no one should be near the pipeline.

The operating personnel must wait in a safe place, as checking the system functionality can be explosive. After the end of the process, the results are evaluated in accordance with SNiP. The pipeline is inspected for, metal explosions, deformations.

Hydraulic test parameters

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

1. Pressure.
2. Temperatures.
3. Exposure time.

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

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

The water temperature should not fall below 5˚С and not rise above 40˚С. The only exceptions are those cases when the temperature of the hydro component is specified in the technical specifications of the object under study. Be that as it may, the air temperature during the test should not fall below the same 5˚С.

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

Testing fire hydrants and water mains

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

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

Pipes made of cast iron and asbestos are tested with a pipeline length of no more than 1 km at a time. Polyethylene water mains are checked in 0.5 km sections. All other water supply systems are checked in sections of no more than 1 km. The holding time for water supply pipes made of metal must be at least 10 m, for polyethylene pipes - at least 30 m.

Heating systems testing

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

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

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

Heating networks are checked only when the boiler and expansion tank are disconnected.

Heating systems are not monitored during winter. If they have worked without breakdowns for up to about three months, then the acceptance of heating networks into operation can be carried out without hydraulic tests. When checking closed heating systems, the control work must be carried out before the furrows are closed. If insulation of heating networks is planned, then - before its installation.

According to SNiP, after the end of the tests of heating systems, they are washed, and at their lowest point, a coupling with a cross section of 60 to 80 mm2 is mounted. Water is drained through it. Washing heating networks carried out with cold water several times, before acquiring transparency. Heating systems are approved if, within 5 minutes, the test pressure in the pipeline does not change by more than 20 kilo Pascal.

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

Hydraulic testing of heating networks and water supply systems

After the completion of hydraulic tests of heating systems in accordance with SNiP, an act of hydraulic tests of heating networks and water supply systems is drawn up, indicating the compliance of the pipeline parameters.

According to SNiP, its form contains the following information:

• title of the position of the head of the enterprise that provides maintenance of heating networks;
• his signature and initials, as well as the date of verification;
• information about the chairman of the commission, as well as its members;
• information on the parameters of heating networks: length, names, etc .;
• conclusions about the control, the conclusion of the commission.

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

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

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

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

On the basis of the regulatory documentation given below, a crimping act has been developed, which is one of the main documents for the delivery of works to the Customer at the facility.

Heating networks must undergo annual hydraulic tests for strength and density (pressure tests) to identify defects after the end of the heating season and carry out repair work. Pressure testing of pipelines accessible for inspection during operation is allowed to be performed 1 time after the end of installation.

Hydraulic pressure testing is carried out with a test pressure of 1.25 working pressure, but not less than 1.6 MPa (16 kgf / cm2). The pipelines are kept under test pressure for at least 5 minutes, after which the pressure is reduced to working pressure. At operating pressure, a thorough inspection of the pipelines is carried out along their entire length. The results of the pressure test are considered satisfactory if during the test no pressure drop occurred and no signs of rupture, leakage or fogging were found in the bodies and stuffing boxes of the valves, in flange joints, etc.

Before the start of the heating season, after the completion of the repair, the heating and hot water supply systems must be subjected to hydraulic pressure testing for strength and density:

Elevator units, air heaters and water heaters for heating and hot water supply - with a working pressure of 1.25, but not less than 1 MPa (10 kgf / cm2);

Heating systems with cast-iron heating devices - working pressure of 1.25, but not more than 0.6 MPa (6 kgf / cm2);

Panel and convector heating systems - with a pressure of 1 MPa (10 kgf / cm2);

Hot water supply systems - with a pressure equal to the working pressure in the system plus 0.5 MPa (5 kgf / cm2), but not more than 1 MPa (10 kgf / cm2).

The hydraulic test should be carried out at positive outdoor temperatures. At outside temperatures below zero, the density check is only possible in exceptional cases.

Systems are considered to pass the test if, during their performance:

No "sweating" of welds or leaks from heating devices, pipelines, fittings and other equipment was found;

When pressurizing water and steam heat consumption systems for 5 minutes. the pressure drop did not exceed 0.02 MPa (0.2 kgf / cm2);

During pressure testing of panel heating systems, the pressure drop within 15 minutes. did not exceed 0.01 MPa (0.1 kgf / cm2);

When pressure testing hot water supply systems, the pressure drop within 10 minutes. did not exceed 0.05 MPa (0.5 kgf / cm2).

The results of the check are documented in an act of pressure testing. If the results of the pressure test do not meet the specified conditions, it is necessary to identify and eliminate the leaks, and then re-check the system for tightness. During hydraulic testing, spring-loaded pressure gauges with an accuracy class of at least 1.5, with a body diameter of at least 160 mm, a scale for a nominal pressure of about 4/3 of the measured pressure, with a scale of 0.01 MPa (0.1 kgf / cm2), which have been verified and sealed by the sovereign.

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Normative documentation, rules and SNiP for pressure testing of the heating system

Brief excerpts from regulatory documents, rules and SNiP for heating pressure testing .

Analyzing the statistics of the questions you ask and realizing that many questions about the pressure testing of the heating system for the majority of our audience remain incomprehensible to you, we decided to make a selection from the necessary points and the Pressure Testing Rules approved by the Ministry of Fuel and Energy of the Russian Federation and SNiP.

All SNiPs and rules contain information on more than 100 pages, which is sometimes difficult to understand, therefore, in order to facilitate the task for you, so that you can look at, and, if necessary, refer to the necessary paragraph of a specific regulatory document, we have processed the applicable regulatory documents and in a short form posted on the site. Explanations to the Rules and SNiP can be found in the article: "Norms and rules for pressure testing the heating system"

1.Rules of technical operation of thermal power plants.

Developed and approved by the Ministry of Fuel and Energy of the Russian Federation. No. 115 dated March 24, 2003.

p. 9.2 Heating, ventilation, air conditioning, hot water supply systems.

Hydraulic tests of the equipment of heat points and heating systems should be carried out separately.
Heat points and heating systems must be tested at least once a year, with a test pressure equal to 1.25 of the operating pressure at the heating network input, but not less than 0.2 MPa (2 kgf / cm 2).

9.2.11 To protect against internal corrosion, heating systems must be constantly filled with deaerated, chemically purified water.

9.2.12 Tests for the strength and density of the equipment of the systems are carried out annually after the end of the heating season to identify defects, as well as before the start of the heating period after the end of the repair.

Clause 9.2.13 tests for strength and density of water heating systems are carried out with test pressure, but not lower:

- Elevator unit, water heaters for heating systems, hot water supply - 1MPa (10kgf / cm 2 or 10Ati.)

- Heating systems with cast-iron heating devices, steel stamped radiators - 0.6 MPa should be taken (6 kgf / cm 2 or 6Ati)

- panel and convector heating systems - 1.0 MPa (10 kgf / cm 2 or 10Ati).

- For heaters of heating and ventilation systems - depending on the operating pressure established by the manufacturer's specifications.

The minimum value of the test pressure during the hydraulic test should be 1.25 of the working pressure, but not less than 0.2 MPa (2 kgf / cm 2 or 2Ati).
Tests of pipelines are carried out in the following order should be performed in compliance with the following basic requirements:

"__7__" __JUNE ________ 2000

for conducting hydraulic tests for strength and density of heating networks,

heat points and heat consumption systems,

on the balance sheet of consumers

Developer: Thermal Inspection

I. ^ GENERAL PART.

1. In accordance with the "Rules for the operation of heat-consuming installations and heating networks of Consumers" and "Safety regulations for the operation of heat-consuming installations and heating networks of consumers", annual hydraulic tests for strength and density must be carried out: heating networks, elevator nodes, air heaters, heating systems and hot water supply on the balance sheet of consumers.
2. Individual tests of hot water supply systems, heating, ventilation are carried out in accordance with the requirements of SNiP 3.05.01-85 "Internal sanitary systems", heating networks - according to the instructions of SNiP 3.05.03-85 "Heating networks", technological heat-consuming installations - in accordance with with the requirements of SNiP 3.05.05-84 "Process equipment and process pipelines".
3. Work on testing the heating network, its individual elements and structures and heat-consuming systems (TPS) should be carried out:

• the personnel of a specialized organization licensed by the State Energy Supervision Authority for the right to carry out such work, at the expense of the consumer, according to a special program agreed with the head of the thermal inspection "Khabarovskgosenergonadzor";
• specialized personnel of the consumer, according to a special program approved by the chief engineer of the enterprise and agreed with the head of the heat inspection "Khabarovskgosenergonadzor".

1.4. The test program should contain:

1.4.1. The document on the basis of which the work on pressure testing is carried out: a work permit signed by the chief engineer of the enterprise, on the balance sheet of which the tested sections of the heat supply system are located.

1.4.2. A diagram of the tested sections of heating networks and heating units with an indication of the pressure tapping points.

1.4.3. The surname list of the persons conducting the tests, indicating the person in charge from the enterprise-consumer of thermal energy.

1.4.4. The layout of the personnel involved in the tests and the means of communication between them.

1.4.5. Methodology for conducting and processing test results.

1.5. For hydraulic pressure testing, use spring pressure gauges with an accuracy class of at least 1.5 with a body diameter of at least 160 mm, a scale for a nominal pressure of about 4/3 of the measured pressure and a graduation rate of at least 0.1 at (0.1 kgf / cm 2) 0, 01 MPa.

The pressure gauges must be sealed by the state certifier. The use of pressure gauges with expired seals and stamps is not allowed.

1.6. Based on the test results, a technical report is drawn up, approved by the head of the thermal inspection "Khabarovskgosenergonadzor".

1.8. Legal entities and individuals carrying out hydraulic tests for the strength and density of heating networks, heating points and heat consumption systems that are on the balance sheet of consumers should be guided by the requirements of this Methodology in their activities.

2. Rules for crimping heating networks,

and heat consumption systems.

A. Tests of heating networks.

2.1. Preliminary hydraulic pressure testing of underground heat pipelines is carried out in sections after they are welded and laid on permanent supports, before equipment is installed on them and channels are closed or trenches are backfilled.

Along the entire length of the test section, free access to the pipelines must be ensured.

Pressure testing is performed in the following order:

a) the tested section of the pipeline is isolated from the existing networks by installing blind flanges or plugs; the use of valves to disconnect the tested section from the operating network is not allowed;

b) the supply and return pipelines, after filling with water and bleeding air, are put under a test pressure equal to 1.25 working pressure, but not lower than 16 kgf / cm 2 and held under this pressure for the time necessary for a thorough inspection and knocking the joints, but not less than 10 min. Tapping is performed with a hammer with a rounded striker weighing no more than 1.5 kg with a handle length of no more than 500 mm; blows must be applied at a distance of at least 100 mm from the weld.

The pressure at the lowest points should not exceed one and a half times the nominal pressure (P y), for which the pipes used for laying the network are designed.

The working pressure for the supply and return pipelines of water heating networks is the highest water pressure, taking into account the operation of pumping substations on the route and the terrain, which may occur during operation or shutdown of network and booster pumps.

If there are automatic pressure regulators and protective devices (safety valves) in the network, the operating pressure is taken to be the highest pressure in the network at the upper limit of setting the protective and regulating devices.

2.2. The test of the valves should be carried out, before their installation on the pipeline with the excess hydraulic pressure set for this pipeline, but not less than 16 kgf / cm 2 for the valves on the supply pipeline and 12 kgf / cm 2 on the return pipeline.

The tests are carried out with two positions of the O-rings:

a) in the open position with a plugged valve flange - to check the tightness of the stuffing box;

b) in the closed position - to check the tightness of the lapping of the rings.

The valve is considered to have passed the test if no pressure drop occurs within 5 minutes.

2.3. The final hydraulic pressure test of the entire heat pipe is carried out together with the installed equipment (valves, expansion joints, drain and air taps, etc.) at an overpressure of 1.25 working pressure, but not less than 16 kgf / cm. All sectional valves and valves on the branches of the tested network must be open.

The duration of the final pressure test is determined by the time required to inspect the network, but must be at least 10 minutes.

2.4. The test results are considered satisfactory if during the test there was no pressure drop across the pressure gauge and no signs of rupture, leakage or sweating were found in welded seams, valve bodies and stuffing boxes, in flange joints, etc.

Note : Testing of pipeline sections that are accessible for inspection during operation (laid in through channels, collectors, as well as aboveground) can be performed 1 time after the installation is complete.

2.5. When the outside air temperature is below 1C, the pipelines are filled with water heated to 50-60C, and pressure testing is performed after the water temperature has dropped to 40C. If defects are found that require a significant time to be eliminated, the pipeline should be immediately emptied, and it should be checked whether there is still water in the lower points of the pipeline.

2.6. At low outdoor temperatures or in the absence of water at the test site, in agreement with the heating network company (power plants, boiler houses), the hydraulic pressure test can be replaced with a pneumatic one, while the test pressure value must be agreed with the Gosgortekhnadzor.
^

B. Tests of heat points, systems

2.7. The equipment of heating points and all underground pipelines of intra-quarter and intra-yard networks after central heating points, as well as pipelines and equipment of heat consumption systems, are subjected to hydraulic pressure testing at an overpressure of 1.25 working pressure, but not lower:

a) for elevator units, heaters of heating and ventilation systems, water heaters of heating and hot water supply systems - not less than 1 MPa (10 kgf / cm 2);

b) for water heating systems with cast iron heating devices - no more than 0.6 MPa (6 kgf / cm 2);

c) for panel and convector heating systems with a pressure of 1 MPa (10 kgf / cm 2);

d) for hot water supply systems with a pressure equal to the working pressure in the system plus 0.5 MPa (0.5 kgf / cm 2), but not more than 1 MPa (10 kgf / cm 2)

The hydraulic test should be carried out at positive outdoor temperatures. At outside temperatures below zero, the density check is only possible in exceptional cases.

2.8. Testing of the equipment of heating points, heat pipelines from central heating points and heat consumption systems is carried out in the following order:

but at least 10 minutes;

b) if during this time no defects or leaks are found, the pressure is brought up to the test pressure (see clause 2.7).

2.9. Steam heating systems should be tested at an overpressure at the top of the system of 2.5 kgf / cm 2, and if the operating overpressure of the system is more than 0.7 kgf / cm 2 - at a pressure equal to the operating pressure plus 1 kgf / cm 2, but not less 3 kgf / cm 2 at the top point of the system.

2.10. Systems are considered to pass the test if, during their performance:

a) no "sweating" of welds or leaks from heating devices, pipelines, fittings and other equipment was found;

b) during pressure testing of water and steam heat consumption systems for 5 minutes, the pressure drop did not exceed 0.02 MPa (0.2 kgf / cm 2);

c) during pressure testing of panel heating systems, the pressure drop within 15 minutes. did not exceed 0.01 MPa (0.1 kgf / cm 2);

d) during pressure testing of hot water supply systems, a drop in pressure within 10 minutes. did not exceed 0.05 MPa (0.5 kgf / cm 2).

The results of the check are documented in an act of pressure testing. If the results of the pressure test do not meet the specified conditions, it is necessary to identify and eliminate the leaks, and then re-check the system for tightness.

The Test Report is signed by the consumer and the Khabarovskgosenergonadzor inspector based on the report (see clause 1.5). The report is attached to the act. A test report without a report is invalid.

3. Safety precautions.

3.1. Before testing the heating network for the design pressure, it is necessary to carefully remove air from the pipelines to be tested.

3.2. During the test of the heating network for the design pressure, heating points and local consumer systems must be disconnected from the tested network.

In case of violation of the density of the shut-off valves at the heating point, consumers should be disconnected by valves located in the chambers of their connection to the heating network, or by valves installed at heating points.

3.3. During the testing of the heating network, a constant watch should be organized at heating points and in consumer systems. Particular attention should be paid to sections of the network in places where pedestrians and vehicles move, sections of channelless laying, sections where there were cases of corrosive destruction of pipes, etc.

3.4. When testing the heating network for the design parameters of the coolant, it is prohibited:

a) perform work on test sites that is not related to testing;

b) stay and descend into chambers, canals, tunnels;

c) be located against the flange connections of pipelines and fittings;

d) eliminate the identified malfunctions.

When testing the heating network for the design pressure of the coolant, it is FORBIDDEN to sharply raise the pressure and increase it above the limit provided for by the test program.

3.5. Simultaneous testing for design pressure and design temperature is prohibited.

3.6. It is allowed to get into the pipeline for inspection and cleaning it from foreign objects only on straight sections with a length of not more than 150 m with a pipeline diameter of at least 0.8 m. in this case, a free exit from both ends of the pipeline section to be inspected and cleaned must be ensured.

The branches, jumpers and connections with other pipelines available on the site must be reliably disconnected.

To inspect and clean the pipeline, at least 3 people should be assigned, of which two should be at both ends of the pipeline and observe the worker.

Work in the pipeline should be in a canvas suit and gloves, boots, knee pads, glasses and a helmet. The end of the life rope of the safety harness must be in the hands of the observer from the side of the pipeline entrance. The observer from the side of the exit from the pipeline must have a lantern illuminating its entire section.

Reliability and energy efficiency of heating networks

-1. The quality of maintaining the technical condition (resource) of heating networks
——1.6. Crimping

Experience in pressure testing of pipelines of heating networks

Experience in pressure testing of pipelines of heating networks

V . M . Lipovskikh , main engineer, Thermal the network JSC Mosenergo

Mosenergo heating networks carry out high pressure hydraulic tests of pipelines. Why and how did we come to this? Let me give you an example. In 1969, in winter, there was a major accident on a pipe with a diameter of 1200 mm on the first line in the Kuzminki area. The factory seam has burst. She was eliminated within a week. Even the sick were taken out of unheated hospitals. Then we began to wonder how to operate heating networks with diameters of 1000 mm, 1200 mm and 1400 mm, when the shutdown of any heating network affects up to 1000-1500 buildings. Today there are attempts to diagnose heating networks, but so far there is no such diagnostics that gives 100% data on the state of a pipeline laid in a non-passable channel or without a channel. We have come to the conclusion that the main method for detecting corroded pipe thinning is hydraulic testing.

Methodology hydraulic trials

Earlier, the Ministry of Energy issued instructions that recommended that tests be carried out twice, and the use of pumps that are in power plants is the second stage pumps. At the same time, the return valve was closed, the pressure rose in both pipes, and a pipeline or heating network with a length of 20-25 kilometers was tested. Of course, the quality of the tests was very, very low. When damage occurred, it was necessary to turn off everything, repair this damage and again raise the pressure. Of course, this approach was wrong, and we abandoned these hydraulic tests.

In 1979, we began to install permanently on heating networks (at power plants and at pumping stations) separate pressure-testing pumps, and with these pumps we began to carry out hydraulic tests. Specialists from VNIIST (Pipeline Institute of the Ministry of Gas Industry) were invited, they worked with us for several years and made the following recommendations.

When calculating and designing heat networks, the factor of repeated loading is not taken into account, although heat pipelines are constantly under conditions of repeated static loads. The main reason for the high damageability of heating networks is the external corrosion of pipes. Failures due to corrosion account for about 95% of all failures. One of the main directions of increasing the reliability of heating networks is the improvement of systems for preventive testing of pipelines by internal pressure. The main purpose of the tests is to identify in the summer those damages that would be potential sources of failure during the period of operation. Tests at standard values ​​of their parameters do not fulfill their main purpose - rejection of weakened places, which leads to heat pipe failures during operation. A method has been developed for determining the test pressure level, based on the requirement that there are no corrosive failures during one operation cycle. It is shown that the required minimum test pressure depends on the working pressure, corrosion rate, pipeline diameter and temporary resistance of the pipe material. From the standpoint of the proposed method for determining the magnitude of the test pressure, the levels of the standard and increased test pressures are analyzed as far as their ability to ensure reliable operation of heat pipelines. The possibility of testing heating networks with a frequency of more than one year is considered. It is shown that if only the corrosion factor is taken into account, then, in principle, it is possible to switch to testing pipelines with a diameter of more than 600 mm with a two-year interval. However, the adoption of such a recommendation can be carried out only after studying the effect on the performance of pipelines of a complex of other factors characteristic of heat pipelines. Polygon experimental studies of the effect of repeated loading by internal pressure of a certain level on the operability of pipelines have been carried out. Sections of new pipes with a diameter of 1200 and 500 mm were tested with an internal pressure of 33 kgf / cm 2 with a number of loading cycles up to 500. After testing, no signs of ruptures and leaks in the pipe walls were found. Laboratory studies to determine the mechanical properties of the base metal of pipes and welded joints of cyclically tested pipes and a comparison with the corresponding indicators of metal maps taken before testing showed that repeated loading at a given level of test pressure and at a given number of loading cycles had practically no effect on the strength , plastic and ductile properties of the base metal of pipes and welded joints, and, consequently, on the operability of pipelines from these pipes. On the basis of the research carried out, a draft manual has been developed for determining the parameters of testing heat networks by internal pressure for strength. The value of the test pressure during strength testing should be taken depending on the purpose of the pipeline - supply or return and its diameter: diameter 1400-900 mm, it is recommended to press the supply pipeline by 28 kgf / cm 2, return - by 20 kgf / cm 2, 800 mm - 33 kgf / cm 2, 700-600 mm - 33 kgf / cm 2, 500 mm - up to 40 kgf / cm 2 and 400-150 mm - 40 kgf / cm 2.

Organization repairs and hydraulic tests

We received such recommendations from the institute, and we began to pressurize at the recommended pressures, but at the same time, a lot of ruptures were found due to poor-quality welding of pipelines at factories, and these pipelines could function for some time, therefore, over time, the pressure testing was reduced. The second point: we have already begun to install axial bellows expansion joints and at high pressures could not withstand the guide supports, i.e. expansion joints bulged, guide supports broke.

Since 1983 we have been extruding pipelines with a diameter of up to 1400 mm at a pressure of 24 kgf / cm 2, reverse - 20 kgf / cm 2, pipelines with a diameter of 800-600 mm at 26 kgf / cm 2 and 500 mm and lower by 28-30 kgf / cm 2.

In order to carry out hydraulic tests, it was necessary to select pumps that could raise the pressure. Were selected pumps CNS-300, CNS-180 and CNS-60. CNS-300 were permanently installed at all power plants, at pumping stations and in a number of areas in separate pavilions. The head that they develop is 400 m, i.e. 40 kgf / cm 2. And at the same time, we have now made 10 mobile presses with CNS-180 pumps. The drive is a YaMZ-240 engine with a capacity of 300 horsepower. This engine is used in heavy duty vehicles.

Pressure testing is carried out separately for each pipe. Separate supply and return pipelines are pressed. Why is that? If we raise the pressure in two pipes simultaneously, then we get off-design loads on dead (fixed) supports. And it was decided to press one pipe at a time. The networks of each district are now divided into sections up to 15-20 km long. A schedule is drawn up for each section, and from May 10 to August 25, each district presses these networks, carries out current repairs.

The organization of repairs and hydraulic tests begins basically already somewhere in November. The heating season has begun, and we are already starting to make up the repair schedule for the next year. First of all, these schedules are coordinated with the power plants. Because the stations are also planning their own major overhauls. After that, the schedule also envisages that the two districts do not press adjacent (neighboring) networks at the same time. If a rupture occurs on a large-diameter pipeline, and it will require major repairs, then we put plugs and power the consumer from the neighboring area. This schedule is approved by Mosenergo, then agreed in the prefectures, in the UTEC. As a rule, we receive this approval in March. The district chiefs transfer these schedules to the councils, prefectures, which carry out their repairs together with us. Among other things, during such hydraulic tests, since they are carried out on crowded streets where there is an active movement of cars, it is very important to draw up a test program. The program is prepared, as a rule, by the leadership of the districts, coordinated with the station, with the services and approved. This program is accompanied by a diagram of the heating networks that are included in the pressure test. According to this scheme, there are control points, as a rule, these are on the final highways, along which the head of the district monitors the pressure during hydraulic testing. This takes into account the piezometric marks of heating networks and, taking into account the marks, the pressure in each pipeline.

As a rule, it is forbidden to put patches on heating networks in the summer. Damage is repaired from start to finish, from good pipe to good. We have such damage in the summer, somewhere up to 4500-5000.

In this case, of course, safety issues are also very important. There were very unpleasant cases, when the slabs were lifted, when the hatches fell off when they burst. When analyzing these cases, it turned out that air from heating networks is not always very thoroughly released. Therefore, always, before turning on the pump again, the head of the district or the person responsible for pressure testing asks his people whether the air vents have been blown everywhere. When the air vents are purged, such explosions, of course, do not happen. In some cases, where hydraulic tests are carried out in especially crowded places, as a rule, we carry out these hydraulic tests at night, so that there are no accidents with people during ruptures.

Perspectives

Of course, pressure testing is not the best way to check. I would say the method is barbaric. Simultaneously with the ruptures, soil reclamation appears in the channels; when one section is replaced, adjacent sections begin to corrode. Now we are trying to eliminate a number of damages, without waiting for hydraulic tests, in advance.

We pin great hopes on the pre-insulated pipelines in polyurethane foam insulation, which we have begun to operate. These pipelines have systems for monitoring the state of thermal insulation. Of course, there is no point in pressing these pipelines, because there is no moisture and no external corrosion, and damage from internal corrosion does not always appear during hydraulic tests. But so far there are instructions that recommend us to press and prepare heating networks annually, and we act according to these instructions.

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Energy saving technologies and methods go to section

Heating network tests are starting and operational. Start-up tests are carried out after the construction of new networks or major repairs. They are intended to determine the suitability of a structure for operation. During operation, sludge accumulates in pipes and equipment, pipelines corrode, and the protective properties of thermal insulation change. The permissible variation of the various characteristics of the structure is periodically verified by operational tests. Start-up and operational tests are divided into pressure tests, hydraulic and thermal tests, and tests for the maximum temperature of the coolant.

Crimping designed to determine the density and mechanical strength of pipelines, fittings and equipment. Start-up pressure testing of channelless networks and in non-passable channels is carried out in two stages: preliminary and final. Pre-pressure testing is carried out as the work is completed in short sections until the installation of stuffing box expansion joints, gate valves on the pipelines and before the closure of the channels or backfilling of trenches. The purpose of the pressure test is to check the strength of the welding under a test overpressure of 1.6 MPa for the time required to inspect and tap the joints. Tapping is carried out with hammers weighing 1.5 kg on a handle with a length of 500 mm, blows are applied on both sides of the seam at a distance of about 150 mm from the joint.

The final pressure testing is done after the completion of all work and installation of all equipment elements on the pipelines, but before applying thermal insulation. When installing networks of seamless pipes, thermal insulation is allowed before testing, 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 the crimping is determined by the time required to inspect the networks.

Pressure testing of the equipment of substations, heat points together with local systems is carried out in two stages. The equipment and pipelines disconnected from the networks are filled with water from the city water supply system, the required test pressure is created by the pressure of pressure testing pumps with manual or mechanical drive. Initially, the system is pressurized to check the tightness of welded and flanged joints of equipment, fittings and pipelines. Then the overpressure is brought to 1.25 of the working pressure, but not lower than the standards established for each type of equipment necessary for checking the strength. The duration of testing of heat points and pipelines outgoing 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 testing, no pressure drop is detected above the established limits, and there are no ruptures, water leaks and fogging in welds, flanged joints and fittings. If breaks and other damage are detected, the water is drained (from the networks in a time not more than 1 hour); defective seams are cut out and digested; leaks are eliminated by tightening the bolts, changing the packing. Then the crimping is repeated. Existing heating networks are pressurized annually at the end of the heating season to identify defects and after major repairs.

Hydraulic tests are intended to determine the actual hydraulic characteristics of the new network and equipment of points or to change 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 the control points, standard manometers, mercury thermometers with a graduation of 1 ° C and normal measuring diaphragms are installed. Tests are carried out with disconnected heating points at maximum and reduced to 80% of the maximum water flow rates. The circulation of water in the networks and branches is ensured by switching on the end jumpers.

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

where P 1, P 2- readings of manometers at the beginning and end of the section, Pa;

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

- the density of the coolant at the appropriate temperature, kg / m 3.

Based on the data of pressure measurements in the supply and return pipelines, a valid piezometric graph is built, and the calculated pressure graph is determined from the water flow rates in the sections. By comparison, deviations of the actual and calculated piezometric graphs are established.

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

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.

Actual specific heat losses are determined by the formulas

; (14.3)

, (14.4)

where q ф1, q ф2- actual specific heat losses in the supply and return pipelines, kW / m; G 1, G p-. average consumption of heating 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 for the return pipeline; l- section length, m

The insulation quality is established by comparing the actual heat loss with the calculated one. For comparison 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 ambient temperature. Heat losses of steam pipelines are determined by the change in enthalpy, steam humidity and the amount of condensate that falls out. Thermal and hydraulic tests of networks are carried out after 3 - 4 years.

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

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 the maximum temperature is maintained for at least 30 minutes.

As the pipelines warm up, at regular intervals, the movements of fixed points on the pipes, U-shaped arms and glasses 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 the pipelines exceeds 25% of the calculated elongation, then a search for places of pinching of pipes, subsidence or shear of fixed supports and other reasons should be undertaken that caused this difference.