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Popularization of gas knowledge-40 gas technology knowledge points

Author: source: Release date: 2017-12-03

  1. Fuels can be divided into three categories: solid, liquid, and gaseous according to their forms, and can be divided into two categories: natural and man-made according to their sources.

  2. The main component of natural gas is methane, and the explosion limit of natural gas is between 5% and 15%. In order to allow users to safely use gas, odor is added to urban gas. The main odorant is tetrahydrothiophene.

  3. Urban gas transmission and distribution systems generally consist of gate stations, gas pipeline networks, gas storage facilities, pressure regulating facilities, management implementation, and monitoring systems.

  4. When the indoor gas pipeline adopts a hose, the maximum allowable working pressure of the hose should not be less than 4 times the design pressure of the pipeline; when the hose is connected to a domestic gas appliance, its length should not exceed 2 meters and there must be no interface; the hose and mobile When connecting industrial gas appliances, the length should not exceed 30 meters, and the interface should not exceed 2.

  5. The installation of indoor gas pipelines using pipes, pipe fittings, pipe accessories, valves and other materials shall comply with the design documents and shall be inspected before installation in accordance with the current national standards. Those who do not pass the test shall not be used.

  6. When installing indoor gas pipelines, the size of the flange gaskets for the flange connection of pipes and equipment should be in accordance with the flange sealing surface. The gasket installation must be placed in the center, and deviations are strictly prohibited. The flange gaskets are not specified in the design documents. When required, oil-resistant asbestos rubber gaskets or PTFE gaskets should be used; oil-resistant asbestos rubber gaskets should be soaked with oil before use.

  7. The clear distance between the ground pipe of the gas pipeline and the external wall of the building should be 100-120mm. The clear distance between the indoor gas pipeline and the wall surface should not be less than 30mm when the pipe diameter is less than DN25; it should not be less than 50mm when the pipe diameter is DN25 to DN40; it should not be less than 60mm when the pipe diameter is equal to DN50; Should not be less than 90mm.

  8. Maximum support distance of steel pipe: Nominal diameter of pipeline is DN15, maximum distance is 2.5m; nominal diameter of pipeline is DN20, maximum distance is 3.0m; nominal diameter of pipeline is DN25, maximum distance is 3.5m; nominal diameter of pipeline is DN32, maximum distance is 4.0m; pipeline The nominal diameter is DN40 and the maximum distance is 4.5m; the nominal diameter of the pipe is DN50 and the maximum distance is 5.0m.

  9. When installing a domestic gas meter at a high position, the bottom of the meter should not be less than 1.4m from the ground; when installing at a low position, the bottom of the meter should not be less than 0.1m; after installation, the gas meter should be horizontal and straight, not inclined; use a high position, multiple meters When hanging on the same wall, the net distance between the tables should not be less than 150mm.

  10. Commercial and industrial enterprise gas meter installation: For gas meters with a rated flow rate of less than 50m3 / h, when installed at a high position, the bottom of the meter should not be less than 1.4m from the indoor floor, and the wall behind the meter should not be less than 30mm, and should be fixed with a table support; When using low-level installation, it should be installed flat on a brick support pier or support with a height of not less than 200mm, and the clear distance from the wall behind the table should not be less than 50mm. A gas meter with a rated flow rate greater than or equal to 50m3 / h shall be installed flat on a brick pier or steel support with a height of not less than 200mm.

  11. Before the installation of gas equipment, the product qualification certificate, product installation manual and quality assurance certificate of the gas equipment should be checked; the product appearance should have the product label and the date of manufacture; the performance, specifications, model and quantity should be checked to meet the requirements of the design documents. Products that do not meet the above inspection conditions must not be installed.

  12. The clear distance between the gas-consuming equipment should meet the requirements for operation and maintenance. The clear distance between the stoves should not be less than 0.5m, the clear distance between the large stoves should not be less than 0.8m, and the oven and other stoves and stoves The clear distance between the platforms should not be less than 1.0m.

  13. The inspection of indoor gas pipelines and gas equipment valves after installation shall meet the following requirements:
    1) The model, specification, strength and tightness test results meet the requirements of the design documents; the installation position and inlet direction are correct, and the connection is firm and tight; the opening and closing is flexible, and the surface is clean;
    2) Inspection quantity: According to different specifications and models, a random inspection of 5%, but not less than 10;
    3) Inspection method: manual inspection and inspection of factory certificate, test list and related record documents.

  14. After the indoor gas pipeline is installed, a strength and tightness test must be performed. The test medium should be air, and water is strictly prohibited. The test pressure gauge should be within the valid period of the inspection, and its range should be 1.5-2 times the maximum pressure measured. The accuracy of the spring pressure gauge should be 0.4.

  15. The indoor gas pipeline strength test pressure should meet the following requirements:
    1) Design pressure is less than 10Kpa, test pressure is 0.1Mpa;
    2) When the design pressure is greater than or equal to 10Kpa, the test pressure is 1.5 times the design pressure and not less than 0.1Mpa.

  16. For gas pipelines with a design pressure of less than 10 Kpa, all joints can be coated with foaming agent during strength test. No leakage is acceptable. For gas pipelines with a design pressure greater than or equal to 10 Kpa, the pressure test should be performed for 0.5h, and all joints should be coated with foaming agent, and no leakage is acceptable; or for 1h, observe the pressure gauge, no pressure drop is acceptable.

  17. The test pressure of low-pressure pipelines should not be less than 5 Kpa. The test time is 15 minutes for residential users and 30 minutes for commercial and industrial users. Observe the pressure gauge and it is qualified without pressure drop. For the tightness test of low-pressure pipelines, U-shaped pressure gauges with a minimum scale of 1mm can be used for pressure measurement.

  18. Urban gas supply units should be equipped with full-time safety management personnel; a 24-hour telephone for repairs should be set up and announced to the society, and emergency repair personnel should be on duty 24 hours.

  19. Direct replacement is the process of replacing air in a gas facility with gas or replacing gas in a gas facility with air.

  20. It is strictly forbidden to bring any kind of flame-proof, non-explosion-proof wireless communication equipment into the production area of the station, and it is strictly forbidden to engage in operations that may produce sparks in the production area of the station without approval.

  21. The operation and maintenance management system shall clearly define the inspection and inspection cycle of gas pipelines, and shall make inspection and inspection records; if problems are found during inspections and inspections, they shall be reported in time and effective measures shall be taken.

  22. Polyethylene plastic pipes for underground gas or medium pressure steel pipes without cathodic protection shall not be less than once every two years.

  23. The inspection content of the pressure regulating device shall include the operation of pressure regulators, filters, valves, safety facilities, instruments, meters and other equipment, and there shall be no abnormal conditions such as leakage.

  24. Inspections of storage tanks in LNG gasification stations should observe changes in liquid level and pressure, and check and record parameters such as liquid level, pressure and temperature of the storage tank.

  25. The gas supply unit shall regularly check the facilities of gas users and publicize the safe use of gas for users.

  26. The gas supply unit shall regularly check the facilities of gas users and publicize the safe use of gas for users.

  27. Rescuers should wear duty signs. Before entering the work area, they should wear antistatic clothing, shoes and protective equipment according to regulations. It is strictly forbidden to put on, take off or take off in the work area. The operation site should be supervised by a person, and it is strictly forbidden to operate alone.

  28. When the polyethylene plastic pipe is broken, cracked, or accidentally damaged, the windproof and heat insulation measures should be taken when the ambient temperature during the repair operation is lower than -5 ° C or the wind (greater than 5).

  29. The urban gas facilities operation, maintenance and emergency repair management department shall submit the operation and maintenance records and materials of emergency repair work to the archives management department.

  30. Polyethylene gas pipelines are strictly forbidden to be used as indoor above-ground pipelines, only for buried pipelines.

  31. Polyethylene gas pipelines shall not pass under buildings and large structures; they shall not pass under sites where flammable, explosive materials and corrosive liquids are piled up; they shall not be laid in the same trench as other pipes or cables.

  32. When the polyethylene gas pipeline is buried under the roadway, the minimum soil thickness of the pipe top should not be less than 0.9m.

  33. Polyethylene gas pipeline connection should adopt electric fusion connection (electric fusion socket connection, electric fusion saddle connection), or thermal fusion connection (thermal fusion socket connection, thermal fusion butt connection, thermal fusion saddle connection). Thread connection is not allowed. And bonding. Polyethylene pipes and metal pipes must be connected by steel-plastic transition joints.

  34. The installation procedures of indoor gas pipelines include construction preparation, surveying and laying out, drilling, piping, installation of pipes and accessories, and pipe fixing.

  35. The inspection of indoor gas pipelines includes visual inspection, inspection and supervision of users.

  36. Gas meter inspection methods include local calibration and regular inspection.

  37. Common faults of gas cookers are tempering, misfire and yellow flame.

  38. Combustion is conditional. It must be the interaction of the three basic conditions of combustible substances, combustion-supporting substances and ignition sources in order to occur.

  39. The basic measures for fire prevention are to eliminate ignition sources, control combustibles and isolate the air.

  40. The sources of ignition can be divided into: open flames, friction and impact, electrical equipment and static electricity.
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