The installation and use of steel sleeve steel steam direct buried prefabricated insulation pipeline
1. The pipeline installed horizontally of the steel sleeve steel steam pipeline should have an appropriate slope, and the slope direction of the project should be consistent with the steam flow direction, and i = 0 should be adopted according to the design requirementsThe slope of 002, the bend and end of the main pipe should be provided with a trap.
2. The diameter of the steam main pipe and the air supply pipe should be installed at the bottom level, and the diameter of the condensate pipe should be concentric. The diameter of the pipe is greater than or equal to 70mm, and the length of the reducer pipe is 300mm; The diameter of the pipe is less than or equal to 50mm, and the length of the reducer pipe is 200mm.
3. When installing auxiliary devices, valves should be set at the position of the inlet and outlet branches of the equipment, and a trap should be installed at the beginning of the equipment.
4. Before the steel jacket steel steam insulation pipe goes down the ditch, it should be checked whether the elevation and width of the ditch at the bottom of the ditch meet the design requirements, and the insulation pipe should be checked for damage to the insulation layer.
5. The steel jacket steel steam insulation pipeline can be welded in sections on the edge of the ditch first, and the length of each section is within the range of 15 30m. Protective measures should be taken for the insulation layer and the end of the outer protection pipe during welding.
6. When releasing the pipe, one end should be fixed on the ground anchor with a rope, and the other end of the pipe section should be pulled by the coiled pipe, and the pipe section should be moved to the edge of the ditch with a crowbar, and the wooden sliding bar should be placed. In order to avoid bending the pipeline, there should be no less than two ropes, and no one should stand in the ditch.
7. The moisture-drain pipe is welded in the steel casing, and the special well chamber or return to the ground is drawn from the bottom, and the moisture-proof pipe leading out of the ground is set with an elbow opening and bent downward, and the height of the elbow from the ground is not less than 025m。
8. For pipeline welding in the ditch, the pipe cavity must be cleaned before connection, leveled and straightened, and the operation pit should be dug out at the welding place, and its size should be convenient for welding operation.
9. The pipeline valve is flanged to connect the non-packing globe valve, the valve must be insulated, its surface temperature is not more than 60 degrees, and the sealing measures are taken at the insulation end of the pipeline at the connection with the valve. Before the installation of the directly buried bellows compensator, the bottom of the ditch should be tamped and leveled, and the compensator should be kept coaxial with the pipeline, and its directionality should be paid attention to during installation. The soil barrier cover can be processed according to the actual outer diameter and compensation amount of the directly buried pipe selected by the project, and the installation quality should comply with the provisions of 05R410.
10. Valves, fittings, compensator piers, etc., according to the requirements of the design drawings and specification atlases, prefabricate the bracket steel plate in advance, weld it with the steam pipe, and weld the steel casing externally to assist the civil engineering to adjust the position of the bracket steel plate and pour concrete.
11. The anti-corrosion of the steel steam insulation pipeline should be treated in advance, the distance between the two ends of the pipeline should be left at the weld, and the anti-corrosion at the weld should be processed after the pressure test.
12. After the installation of the steel jacket steel steam insulation pipeline is completed, the tightness test and pipeline hydraulic test should be carried out according to the design requirements and specifications, and the hidden inspection and pressure test procedures should be carried out before the pressure test. When the pressure test should be slowly pressurized, when the pressure reaches a certain value, the pipeline should be stopped for inspection, and then continue to pressurize without problems, generally to the test pressure level, when the pressure reaches the test pressure to stop pressurization, keep under the test pressure for 10 minutes. Then the pressure is lowered to the working pressure and kept for a minute inspection, and no pressure drop and no leakage are qualified. The pressure drop should be in accordance with the provisions in GB50235-97.
13. After the tightness test is completed, the steam pressure should be purged with steam, the steam pressure of the blowing should not be greater than 75% of the working pressure of the pipeline, and the flow rate should not be less than 30m s for purging, the number of times should not be less than 3 times, and the time of each time should not be less than 15 minutes.