Pipes

Hydraulic testing of pipelines: stages of checks, drawing up an act

March 30, 2020

Hydraulic testing of pipelines is a set of measures, which can be carried out at various stages of pipeline operation, but most often these tests are performed immediately after laying the communication, before its launch. Networks, working under pressure, must be checked (in accordance with the provisions of SNiP) on various defects. This is necessary for that, to prevent an emergency.

Hydraulic testing is a check of the condition and operability of the pipeline using pressure, which exceeds the work

What are hydraulic tests for??

During hydraulic tests, the strength and tightness of the structure is determined, its volume is also determined. All types of pipelines undergo similar inspections at various operational stages.

There are three options, when hydraulic checks are mandatory, regardless of the direction of communication:

  • in the process of production of pipes, a quality check is carried out without fail. Also, other components for pipelines undergo corresponding tests;
  • appropriate tests are also carried out after the installation of the pipeline structure, checking communication for operability;
  • testing of pipelines is also carried out during operation for preventive purposes.

Such tests can reveal certain inconsistencies of pipes or their components with quality standards, prescribed in laws. Conducting verification measures is a necessary point of equipment operation, working under pressure.

Usually, the verification procedure includes several important points. Extreme conditions are created for hydraulic testing, to accurately determine the reliability of the pipeline. The test pressure in this case may be more than usual 1,25-1,5 times.

Peculiarities of hydraulic tests

The test pressure is pumped into the pipeline slowly and smoothly, so as not to cause water hammer or other emergency situations. Pressure indicators, as mentioned above, exceed standard operating norms.

The test equipment is equipped with devices, that allow you to control the pressure in the system

The force of liquid supply is fixed on the measuring devices (manometers), therefore, it is possible to control and regulate the process. For SNiP, the supply of liquid is accompanied by the accumulation of gas at various points of communication. This is a very important point, which must be controlled, to avoid unforeseen situations.

After filling the pipeline structure with water, the equipment is under elevated pressure, test pressure. This period is called the exposure time.

Importantly! There is one important rule — during the exposure of the equipment, it is necessary to exclude the possibility of jumps in the test pressure. The test pressure readings should be unchanged.

After the exposure period, work is carried out to reduce the pressure to normal values. During the inspection, it is forbidden for anyone to be in the immediate vicinity of the tested pipeline. The working staff is located in a safe place.

When the hydraulic test is done, the communication is inspected for damage and the information received is evaluated in accordance with the SNiP.

Under what conditions should hydraulic testing of pipelines be carried out?

Hydraulic testing of pipelines is a complex activity, which requires some preparation. Tests must comply with building codes and regulations, therefore, such inspections are carried out only by highly qualified specialists.

The tests are carried out strictly according to the accepted norms and rules, and the process is managed by specialists

In order to carry out such a pipeline inspection, the following conditions must be observed:

  • points of use in the riser are activated simultaneously for testing, however, this provision is not always mandatory and is determined individually depending on the specific case;
  • characteristics of towel drying devices are checked when testing hot water supply systems;
  • temperature measurements are performed only at the extreme points in the structure;
  • after testing, it is necessary to completely remove water from the system;
  • communication is filled from the bottom up. This rule is necessary for the correct displacement of air and allows you to avoid emergency situations, associated with excess pressure, as well as air traffic jams.
  • the initial stage of filling the communication refers only to the main riser, and only at the next stages, the risers are filled, that branch off from the main one.
  • during hydraulic tests, the ambient temperature should not be lower, than +5 ° C.

These conditions must be observed regardless of the type of pipeline and working environment, which he transports.

Hydraulic checks are carried out for the following equipment:

  • internal fire water pipes;
  • hot and cold water supply systems;
  • heating systems.

Various types of pipelines are tested, including heating and domestic hot water networks

Sequence of works

Hydraulic inspection measures are performed in a certain sequence. Let's consider the main stages of this process:

  1. Cleaning of the pipeline network.
  2. Installation of cranes, plugs and measuring equipment (manometers).
  3. Connection of water and hydraulic press.
  4. Filling the communication with water to the required level.
  5. Inspection of the pipeline structure for damage (deformed places are noted).
  6. Repair of problem areas.
  7. Performing a recheck.
  8. Disconnection from the pipeline and removal of liquid from the system.
  9. Dismantling of cranes, plugs and manometers.

All these manipulations must be carried out in accordance with building regulations and rules, to exclude negligence and emergency situations.

Preparatory work

Before conducting hydraulic tests, it is necessary to perform a number of preparatory stages. Let's consider the sequence of preparatory work:

  1. The pipeline is divided into conventional parts.
  2. A superficial visual inspection of the communication is carried out.
  3. Technical documentation is being checked.
  4. The structure is fixed in (places of conditional distributions) valves, as well as the necessary plugs.
  5. A temporary communication is attached to the Press machines and fillers.
  6. The tested section is disconnected from the main line and equipped with the necessary shut-off valves (plugs).
  7. Next, the tested pipeline segment is disconnected from the equipment.

For work, equipment is used to increase the pressure in the pipes - pumps, compressors and other devices

Importantly! It is strictly forbidden to equip the tested section of the communication with a shut-off valve of the same pipeline.

To check the strength indicators of the pipeline structure, it is connected to various hydraulic equipment (compressors, pumping stations, etc. D.), Which is able to create the necessary pressure in the pipeline at a distance of two valves.

Testing for strength and tightness

A preliminary check of communication for strength and tightness indicators is carried out in the following sequence:

Durability check. For this purpose, a test room is created in the pipeline, increased pressure and withstand it closely 10 minutes. As mentioned above, during exposure can be allowed, to lower the pressure. Usually, the check is broken, if the pressure decreases by more than 0,1 MPa. At the end of the time, the test pressure is reduced to standard values ​​and maintained by continuous pumping of liquid. After that, a design review is performed, which is aimed at detecting damage. If no defects are found, a second strength test is performed. When deformations are detected in the pipeline structure, they are eliminated and repeated testing is carried out. Separate parts of pipeline communication are checked at different times. The duration of the hydraulic test cannot be less, than 10 minutes.

Check for tightness. After, how communication passed the durability test, the pipeline is tested for tightness. Airtightness is checked as follows:

  1. The time of the start of the inspection is recorded.
  2. The initial liquid level is determined in the measuring tank.
  3. When the first two points are fulfilled, monitoring of the decrease in the pressure indicator in the structure begins.

Strict pressure control is required during the test, its indicator should not change during the entire exposure period

This sequence must be strictly followed during hydraulic testing of pipelines.

Determination of additional volume of water

After performing the leak test, usually, the calculation of the additional volume of liquid in the system follows. This process takes place in the following sequence:

  1. The pressure level in the structure is increased again by pumping liquid from the measuring tank. The pressure indicator should be the same, as with hydraulic testing, that is, to exceed the standard indicators in 1,25-1,5 times.
  2. Time, when the tightness test is over, must be remembered.
  3. At the third stage, the final water level in the measuring tank is measured.
  4. Next, the time period is determined, which was occupied by the communication check (in minutes).
  5. Calculation of the volume of liquid, pump from the measuring tank (for 1 case).
  6. Calculation of the difference between pumped and removed from the pipeline liquid (for 2 cases).
  7. Calculation of the actual consumption of additionally injected liquid according to the formula: qn = Q / (Tk-Tn).

drawing up an act

After conducting hydraulic tests, it is necessary to draw up an act, which indicates, that inspections were carried out taking into account building regulations and rules, and also contains an account of that, that the pipeline structure has withstood them. This document is drawn up by the inspector.

Based on the results of the tests, an act is drawn up, which confirms the serviceability of the pipeline and the safety of its operation

Act, required, should include the following items:

  • the name of the pipeline;
  • company name, which carries out technical supervision;
  • necessary data, which tell about the indicators of the test pressure and the duration of the tests;
  • pressure reduction data;
  • description of defects, detected during the inspection or a record of their absence.
  • the date of the tests;
  • conclusion of the commission.

Hydraulic checks can be carried out in two ways:

  1. Gauge. The check is carried out using special measuring devices. They record pressure readings during all test manipulations.

The manometric method of pipeline inspection allows the inspector to make the necessary calculations and measure the pressure in the structure during testing.

  1. Hydrostatic. Checking by this method shows, exactly how communication will behave in non-standard operating conditions (with increased pressure, etc. P.). This method is the most popular.

Testing of internal fire water mains

Ready and already in use fire water mains are checked by creating a test pressure. Conditions for testing the fire water supply system, correspond to hydraulic conditions.

Fire water mains are also tested under high pressure

Importantly! Hydraulic checks of the finished fire pipeline must be carried out no less 2 once a year.

Such tests are also carried out in already operated buildings, therefore, a reduced pressure indicator is used to check fire communication. exept this, the test procedure includes measurements on a special tap, which is called dictates.

Inspections are also carried out, which determine the water output in the fire protection system, they are necessary for fire hydrants furthest from the water source. An inspection is mandatory, which is aimed at detecting possible leaks in the fire protection system. All received data are first entered in the test log, and then into the act. After that, they are compared with the standards prescribed in SNiP.

Testing of water supply systems

Inspection of water supply systems is also carried out in accordance with building regulations and rules. Hydraulic tests are carried out: after laying the communication, before filling the canal, after filling the channel (to the installation of the corresponding components). Inspection of pipeline communications, which refer to pressure, is conducted in accordance with SNiP U III-3-81.

Pipes, made of cast iron material or asbestos cement, are checked in case, if the length of the pipeline does not exceed 1 kilometers (for 1 trial). Polyethylene (PE) pipelines are tested by segments of 500 meters. Pipelines made of any other materials are checked by sections, which have a length of 1 kilometers.

The exposure time depends on the material, from which the pipes of the tested pipeline are made

And also worth noting, that the exposure time for metal and asbestos-cement pipes is no less 10 min, and for PE pipes - not less than 30 min.

Testing of heating systems

Hydraulic tests of heating communications are performed immediately after their installation. The communication is filled with water from the bottom up. This contributes to the quiet withdrawal of air from the system. It is important to know, that filling the system with water should not happen very quickly, otherwise air jams may occur.

Inspections of heating communications are performed taking into account SNiP and involve the involvement of the following pressure indicators:

  • standard, working pressure, which is 100 kPa;
  • test pressure with value 300 kPa.

The important point is that, that the testing of heat network pipelines should be carried out with the boiler disconnected. It is also necessary to disconnect the expansion tank in advance. Verification measures, aimed at identifying and eliminating defects in heating systems, are not held in the winter period. If the heating network functioned normally during 3 months — it can be operated without hydraulic checks. Inspection of the closed heating pipeline is performed before the trench is filled, as well as for the installation of heat-insulating material.

pay attention! Measuring equipment must be checked before starting hydraulic tests.

According to building regulations and rules, after carrying out all stages of tests, the heat network is washed and a special connecting element — a coupling — is installed at its lower point (with the intersection from 60 to 80 mm). Fluid is removed from the system through this coupling. The heating communication is flushed several times with cold water.