Gas pipeline pressure testing: leak testing

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One of the most important stages in organizing the gasification of a private house is to pressurize the gas pipeline, making it possible to make sure that the system is done correctly even before it is connected to the main gas main.

Control tests carried out by representatives of the gas service. However, the owner of the house does not hurt to know the order and rules of work, do you agree? Information will help to better understand the design features of the pipeline, timely identify weak points and possible failures in the pipeline.

The article describes in detail the procedure for conducting a technical inspection, the requirements for documenting the connection of the pipeline and the nuances of crimping a private gas network.

The content of the article:

  • Performing a technical check
  • Preparatory work and activities
  • Monitoring the tightness of the pipeline
  • Example of crimping a private gas pipeline
  • Some significant moments
  • Conclusions and useful video on the topic

Performing a technical check

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The control pressure testing of gas networks is performed not only before the launch of the new branch, but also after its repair. Routine pressure testing is performed before the gas pipeline is put into operation.

The same procedure is repeated during scheduled inspections of the system state. In the course of its implementation, it is possible to detect defects that already existed in the pipes and flaws allowed in the course of welding. Only after the complete elimination of all deficiencies is it allowed to use the gas system.

Before starting the procedure it is recommended to perform a technical check of the state of the pipeline. There are instructions and devices that allow such an examination with the help of technical means.

The inspection is carried out by a team, two operators investigate and assess the condition of the insulation coating, another specialist fixes the places of possible leakage.

At the same time, it is necessary to examine not only pipes and fittings, but also wells and gas pipes, to ensure that there is no gas contamination. If even the slightest leak is detected, the condition of the structure is declared emergency and immediately begins to fix the problem.

Operators who carry out pipe line inspections must follow certain safety rules:

  • inspectors should wear special vests, especially when working near highways;
  • scheduled inspections near the roads are carried out during periods when traffic intensity is minimal;
  • If destruction of the insulation layer is detected, the damaged area should be immediately examined, paying attention not only to the insulation condition, but also to the integrity of the gas pipe.

For a detailed survey, it may be necessary to dig a hole. In some places, due to the availability of infrastructure, the use of research equipment can be difficult. In such a situation, the creation of the pit will be required to ensure the integrity of the insulation coating or to identify the places of its destruction.

Technical inspection of the pipeline

Before starting the crimping test, it is necessary to check the state of the pipeline and the equipment with the help of technical means in order to preliminarily identify the places of possible damage.

Another way to study the state of the pipeline is to drill a well. Instruments that analyze the state of the air and make it possible to detect a possible gas leak are introduced into such an opening.

During such procedures, it should be remembered that the use of open fire is closer than three meters away from communications filled with gas, is unacceptable.

Preparatory work and activities

Crimping a gas network section is considered the most technologically advanced method for identifying design flaws. Before beginning this procedure, you must perform preparatory activities. This is required in accordance with safety requirements.

Technical documentation

Before proceeding with the pressure test of the gas system, the person responsible for the work must examine the technical documentation and verify it with the actual location of the gas pipeline (+)

First, you should examine in detail the technical documentation relating to the surveyed object.

Based on this information, the location of such elements as:

  • plug;
  • set of instrumentation;
  • a set of special sensors;
  • compressor.

Discussion procedures for upcoming procedures are conducted with staff performing pressure testing, as well as instructions on how to observe the necessary safety rules. All control measures before a new gas pipeline system is put into operation are carried out by employees of the local gas industry.

The basis for pressure testing before launching a new gas pipeline is the corresponding statement of the owner of a private house or other gasified object. All other work on gas line connection also performed by gas service workers.

Gas pipeline purge

Before starting the pressing operation, the gas system is first flushed with a stream of air under pressure to remove accumulated contaminants from the pipes.

Pressing operations should be carried out in the presence of gas industry employees, as well as Representatives of enterprises performing installation work on the arrangement of external and internal gas network.

Specialists should have an executive design drawing. All activities are carried out in accordance with the instruction manual of the pipeline. Before crimping it is necessary to blow the gas line with air in order to clean it of possible contamination.

Permission to launch a new gas network can only be obtained after a successful crimp. The entire procedure should be managed by only one person who is responsible for the safe conduct of work. This specialist must have the appropriate qualifications.

For the installation and removal of gas plugs, responsibility is usually borne by the master of the gas section, and these operations are performed by employees with an appropriate permit and qualification not lower than the fourth discharge.

The specialist responsible for the crimping works first performs a verification of the provided executive drawings and the actual location of the network elements, all devices and gas pipes. Data must match.

Then a control inspection of gas equipment is carried out, it is checked how well they work measuring devices.

After that, you should make sure that the protective devices work normally, the alarm is properly connected, and the system is locked in accordance with the settings. The condition and operation of the slam-shut valve of the boiler, burners, etc. are also checked.

All operations on the test pressure testing of a gas pipeline must be executed by issuing an admission order, which is issued additionally. Such a document may be issued only to qualified professionals.

Monitoring the tightness of the pipeline

Only after obtaining a satisfactory result according to the procedures described above, it is possible to proceed with the pressing operations. To do this, the system is connected to a special compressor and the pipes are filled with air under pressure. Then the design is examined for deficiencies.

Gas pipeline pressure test

Air is injected into the system to perform pressing operations. If the required pressure level is held for a certain time, the result of the test can be considered positive.

If deficiencies are identified, they are eliminated; if the system is completely sealed, it is connected to a common gas main. In the process of preparation, you will have to remove and install special plugs, the swiveling elements can be replaced with threaded connections.

In general, the procedure for pressing operations should consist of the following operations:

  1. To disconnect from the main line of the section to be subjected to the procedure, it is necessary to close the high pressure valve and the low pressure network valve.
  2. After that, plugs are inserted.
  3. When the flange ruptures, shunt jumpers are used.
  4. To release the gas inside the system, you must use a special hose from rubberized cloth or perform this operation through a candle, which is usually set to condensate collector.
  5. The gas is burned, and if there is no way to do it safely, it is moved for safe storage.
  6. Now you need to install adapters for connecting pressure gauges and compressor.
  7. For pressure testing systems increased length is recommended to use hand pumps.

Typically, the test pressure test is performed under a working pressure of 0.2 MPa. The recommended pressure limit is 10 daPa / h. In some industries, it is recommended to use a pressure of 0.1 MPa for pressure testing the internal gas pipeline, and the permissible level of the index drop is 60 daPa / h or less.

Pressure testing gas pipes inside the house

Pressure testing of gas pipes inside the house is carried out along the entire length of the system from the valve at the entrance to the house to connection to gas consumers, for example, to the boiler

At non-production facilities, including the construction of gas pipelines in residential premises, test pressure testing is performed under a pressure of 500 daPa / h. The allowable pressure drop in these cases is 20 daPa in five minutes. Tanks intended for the storage of liquefied gas are pressurized at 0.3 MPa / h.

If a pressure inside the system remains stable during the test time, the result of crimping is considered positive. If this situation is achieved, then the specialists remove the hoses connecting the system with the air duct.

At the same time, it is necessary to check the status of shut-off communications installed in the area between the air duct and the gas pipeline. After that install the plugs on the fittings.

If during pressure testing it was not possible to achieve stable indicators of pressure in the system, the result of the procedure is considered negative. In this case, perform a technical inspection of the system to identify deficiencies and eliminate them. After this procedure is repeated to verify the quality of the work performed.

Pressure gauge for gas pipeline testing

It is recommended to use pressure gauges with a sufficiently high degree of accuracy for pressure testing in order to obtain correct results during the pipeline leak test.

Only after a stable pressure has been established in the system, can the pressure testing be considered complete. If the system status check is unsatisfactory, permission to connect to the trunk will not be issued.

The reason for the refusal to enter the pipeline into operation may also be violations committed during the pressure test.

After the pressure test is completed, the pressure inside the structure is reduced to the atmospheric level. Then install the necessary valves and equipment, after which you need another 10 minutes to keep the system under operating pressure. To check the tightness in places of detachable joints at this stage use soap emulsion.

To eliminate the detected defects, in accordance with the rules, you must first reduce the pressure in the system to atmospheric. If after unsuccessful crimping welding works were performed, their quality should be checked by physical methods.

Connection to the gas pipeline

After completing the pressing operations, a corresponding certificate is issued, on the basis of which the gas supply specialists will connect to the main gas pipeline

The procedure is recorded in the journal with operational documentation. At the end of the test and pressure testing, the results of the work are reflected in the acceptance report. This document should be stored together with other technical documentation related to the pipeline. In addition, the results of crimping are recorded in the construction passport.

Example of crimping a private gas pipeline

The working documentation indicates the diameter and design features of the gas pipeline, in accordance with which fittings necessary for tapping control equipment are selected. The part of the pipe located underground is cut so that some stock remains.

After that, the compressor is connected to the pipe and the gas pipeline is first blown through. A powerful stream of air blows particles of debris, water and other extraneous contents out of the system.

After that you need to install plugs on the ends of the gas system. At one end of the pipe, where there is a basement, you should put a special adapter that allows you to attach metal equipment to the plastic construction.

gas pressure testing

Compression operations provide an opportunity to ensure the tightness of the gas pipeline system and ensure its trouble-free operation for a long time.

Here is installed the pressure gauge and tap. After all the necessary devices are mounted, air is supplied to the system so that the pressure inside reaches the desired limit. Now you need to withstand control time to ensure that the pressure remains stable. Manometer readings are recorded.

This is the easiest procedure to check a private gas pipeline for leak tightness. To perform such operations on high and medium pressure communications, it is required to use special high-precision equipment, and to invite specialists with appropriate qualifications.

Some significant moments

The air pressure in the gas system should be kept constant until the system is connected to the main gas pipeline. Air is usually used for pressure testing, but the procedure can also be carried out with an inert gas.

If a gas pipeline is being connected at an enterprise, the procedure should be documented with relevant documents, such as an acceptance certificate, order appointing the person in charge of the procedure, the instruction manual of the network and equipment, safety instructions, etc.

The pipeline, which is subjected to pressure testing, in some cases it is considered expedient to split into several sections, which are checked separately. To do this, install special plugs. It is possible for the same purpose to use linear armature in combination with locking devices.

The procedure of pressing

Although the procedure for performing work during pressure testing does not look too complicated, it may take several days to complete all the necessary procedures.

It is necessary to correlate the type of valve selected and the pressure drop that is permissible for it. If this figure is lower than the required for testing, you should use plugs.

The network in residential buildings, as well as in administrative buildings, boiler rooms, change houses and other similar objects is checked by the entire length: from the locking device at the entrance of the network to the building where it is connected to the equipment for which it is used gas.

To perform the gas line tightness test, the accuracy of pressure gauges is 0.15, although devices with an accuracy of 0.4-0.6 are allowed. If the test should be carried out at a pressure of less than 0.01 MPa, it is recommended to use V-type liquid devices.

The part of the pipeline located under the ground should be pressurized after the structures are laid in a trench and drowned. If full filling is considered inexpedient for some reason, then the pipes should be covered with a layer of soil of at least 20 cm. Welded connections of steel communications should be carefully insulated.

Crimping gas pipes underground

Pressure testing of gas pipes, located underground, is performed only after the trench is completely filled up, or if the soil layer is at least 20 cm.

Before starting the pressure test, you need to wait until the air inside the structure under test pressure acquires the same temperature as the surrounding soil.

If it is necessary to check the tightness of the network, laid in cases through barriers of various origins, then this must be done three times: directly after welding the communications, after putting it into the case and filling it with soil, and also after this segment is connected to the general gas pipeline the system.

Pipe condition check

If after unsuccessful pressure testing of the gas pipeline, welding of metal pipes was performed, then all the places of such connections should be checked for leaks using a soap emulsion

Sometimes the last stage can be abandoned if there are no objections from the operational enterprise. If the transition was performed using directional drilling, or if the welds under transitions are absent, it is possible to carry out pressure testing of this site already after connecting to the main gas pipeline.

In the same way perform pressure testing, if for welding of polyethylene pipes In the transition area, high-precision automatic equipment or a system of embedded heaters was used.

Additional requirements, features, methods and order of tie-in to the gas pipeline are described in the articles:

  1. How to crash into a gas pipeline: technical requirements and features of the work
  2. Gasification of a country house: the stages of connecting the cottage to the main gas pipeline

Conclusions and useful video on the topic

Detailed information on the procedure of this type is presented here:

Pressure testing is a necessary measure before launching the gas pipeline system, as well as after its repair. It must be performed in accordance with the instructions and requirements in order to ensure a sufficient level of safety and reliability of the gas pipeline.

Is there anything to supplement, or have any questions on the topic of gas pipeline pressure testing? Please leave comments on the publication and participate in discussions. The form for communication is in the lower block.

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