Test pressure of thermal networks. Rules for pressure testing of heating networks

General information

Based on the Rules technical operation thermal power plants (approved by order of the Ministry of Energy of the Russian Federation dated March 24, 2003 N 115), heating network enterprises during the operation of thermal network systems must ensure the reliability of heat supply to consumers, the supply of heat carriers (water and steam) to them with a flow rate and parameters in accordance with temperature chart regulation and differential pressure at the inlet.

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

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

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

The minimum value of the test pressure during a hydraulic test 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) within the limits between the minimum and maximum values.

Hydraulic tests are carried out by the person responsible for safe operation heating networks together with personnel authorized to operate heating networks.

Hydraulic tests

When conducting hydraulic tests for the strength and density of heat networks, the equipment of heat networks (stuffing box, bellows compensators, etc.), as well as sections of pipelines and connected heat-consuming power plants that are not involved in the tests, should be turned off 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 section of the pipeline under test (after filling it with water and venting), set the test pressure (control by pressure gauge);

the pressure in the pipeline should be increased smoothly;

the rate of pressure rise must be specified in the regulatory and technical documentation (NTD) for the pipeline.

Strength and density tests 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 at least 1.5 with a case diameter of at least 160 mm. The pressure gauge must be selected from the condition that the measured pressure value is within 2/3 of the instrument scale; test pressure must be provided at the top point (mark) of the pipelines; water temperature should not be lower than 5 °C and not higher than 40 °C; 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 pipelines along their entire length is carried out.

The test results are considered satisfactory if during the test there was no pressure drop and no signs of rupture, leakage or fogging were found in the welds, as well as leaks in the base metal, in valve bodies and glands, 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 their implementation there was no pressure drop, no signs of rupture, leakage or fogging in welds, as well as leaks in the base metal, flange joints, fittings, compensators and other elements of pipelines , there are no signs of shear or deformation of the pipeline and fixed supports.

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Hydraulic testing of 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, the power of the water source (river, pond, lake, water supply), working conditions, terrain, etc.

During hydraulic testing of heating networks, the sequence of work is as follows:
- carry out cleaning of heat pipelines;
- install pressure gauges, plugs and taps;
- connect water and Hydraulic Press;
- Fill pipes with water 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.

For filling pipelines with water and good removal from the air pipes, the water supply is connected to the lower part of the heat pipe. Near each air crane it is necessary to put a duty officer. First, only air enters through the air vents, then the air-water mixture and, finally, only water. When the outlet is only water, the valve is closed. Then the tap is periodically opened two or three 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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Hydraulic testing of pipelines of heating networks (pressure testing) is carried out with water with a temperature not lower than + 5 ° C. Pipelines and their parts must be subjected to a hydraulic test with a test pressure equal to 1.25 working pressure, but not less than 1.57 MPa (16 kgf / cm 2 ) for supply pipes and 1.18 MPa (12 kgf / cm 2) for return pipes.

According to the Rules for Technical Operation (PTE) of heating networks and heating points of the MZHKH RSFSR, water heating networks from boiler houses equipped with cast iron boilers, are tested with a pressure equal to 1.25 working pressure in the supply manifold, but not less than 0.59 MPa (6 kgf / cm 2). The pressure must be measured using two tested pressure gauges with an accuracy class of at least 1.5.

Hydraulic tests of heat networks with channel and channelless laying are carried out in two stages (preliminary and final). The preliminary test is done on small areas- up to 1 km, final - when performing all construction and installation works. Both are carried out after the installation and welding of the movable supports, installation and backfilling of the fixed supports, but before the pipes and fittings are covered with thermal insulation. When installing pipelines from seamless pipes, hydraulic testing of pipelines can also be carried out after the pipes are insulated, but on condition that the welded joints are free from insulation, not covered with waterproofing and located in places accessible for inspection.

If no pressure drop is detected during the test pressure tests, the pressure in the tested section of the pipeline is reduced to the working one and at this pressure the welded joints are tapped with a hammer with a rounded head 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 150 mm from the weld on both sides. The test results are considered satisfactory if during the test the pressure did not decrease, and no signs of rupture, leakage or sweating were found in the pipe welds.

Drainage of water after testing or detection of defects should be carried out immediately with a final air purge of the emptied heat pipelines, and it should be checked whether water has remained at the lowest points of the pipeline.

Hydraulic test individual pipes produced according to GOST 3845-75. For hydraulic testing of pipes of small diameters and lengths of sections, manual hydraulic pumps are used, and for large diameters piston pumps with mechanical and electrical drive.

Pneumatic testing of pipelines. According to SNiP III-30-74, testing of pipelines for strength and tightness instead of hydraulic can be done pneumatically at the discretion of the building organization (heating network enterprises) if it is difficult to carry out hydraulic test (winter time, lack of water at the test site, etc.). Pneumatic tests must be carried out in accordance with the rules of SP 298-65 of the Gosstroy of the USSR. According to the rules, pneumatic testing of pipelines of heating networks with a coolant temperature above 120 ° C, steam pipelines with a pressure above 0.098 MPa (1 kgf / cm 2) should be carried out with a test pressure equal to the working pressure with a coefficient of 1.25, but not less than 1.57 MPa (16 kgf / cm 2) for supply and 0.98 MPa (10 kgf / cm 2) for return pipelines.

Considering that in installation conditions it is practically impossible to create such a test pressure, and also that with such a large test pressure with air, a great danger would be created for personnel, and in urban conditions and for the population, replacing a hydraulic test with a pneumatic one should be avoided if possible. In the absence of water, it is allowed to carry out a preliminary test of pipelines with air pressure of 0.59 MPa (6 kgf / cm 2). Under this pressure, the pipeline is maintained for 30 minutes, then the pressure is reduced to 0.29 MPa (3 kgf / cm 2) and the pipelines are inspected. Air leakage is detected by soaping the joints, by sound, odorization or smoke in the air in the pipeline. After the preliminary pneumatic test, the final test is carried out hydraulically.

There are 4 types of heat network tests:

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

Q = cG(t 1 - t 2) £ Q norms = q l *l,

where q l - heat loss 1m pipeline, determined by SNiP " Thermal insulation pipelines and equipment”.

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

Strength and tightness tests.

There are 2 types of tests:

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

Hydraulic tests.

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

Order of conduct:

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

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

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

Devices: 2 pressure gauges, pressure source - compressor.

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

Safety precautions:

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

Design Temperature Tests

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

Tests to determine thermal and hydraulic losses

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

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