Suzhou Qiaohui Warm Communication Sharing: Installation and construction requirements of ventilation pipes in underground garages?

The installation of ventilation pipes in underground garages should strictly follow the principles of safety, standardization and practicality, and the core should focus on pipe material selection, installation accuracy, fire prevention and explosion protection and system adaptability, so as to ensure that the ventilation efficiency reaches the standard and meets the fire and building safety standards.

First, preliminary preparation: lay the foundation for construction.

The preliminary preparation needs to clarify the construction basis and the state of materials and equipment to avoid subsequent rework.

Drawing checking and site investigation: Before construction, it is necessary to check the direction, diameter, tuyere position and distance from other pipelines (such as fire pipes and cable bridges) of ventilation pipes against the design drawings to ensure no space conflict; At the same time, explore the underground garage site, confirm the ground flatness, verticality of the wall surface, and the position and size of reserved holes (such as through walls and floor openings). If there is any deviation, it is necessary to communicate and adjust in advance, and the size of the hole should be 100-200mm larger than the outside diameter of the pipeline to facilitate subsequent plugging.

Inspection of materials and equipment: the galvanized steel plate is preferred for ventilation pipes (the thickness is determined according to the pipe diameter, for example, the thickness is ≥0.5mm when the pipe diameter is ≤500mm, and ≥0.6mm when the pipe diameter is 500-1000mm). It is necessary to check whether the surface of the steel plate has defects such as zinc layer falling off and scratches, and there should be quality certificates. Fans, air valves, tuyeres and other equipment need to check that the models and specifications are consistent with the design, and power on to test whether the fans operate normally and whether the air valve switch is flexible, so as to ensure trouble-free before entering the site.

Construction scheme and safety disclosure: formulate detailed construction scheme, and define construction sequence, personnel division and schedule; Conduct safety disclosure for construction personnel, and emphasize matters needing attention in underground garage operation, such as temporary electricity consumption specification (using 36V safe voltage lighting), aerial work protection (scaffolding should meet bearing standards), and storage location and use method of fire fighting equipment.

Second, pipeline processing and assembly: ensure the installation accuracy.

Pipeline processing and assembly need to control the dimensional error, ensure the tight interface and reduce the air leakage rate.

Pipeline processing: the galvanized steel plate is cut mechanically, and the cutting edge should be smooth and burr-free; When connecting the pipe bite, the bite width should conform to the specifications (for example, the width of a single bite is 6-10mm, which should be adjusted according to the thickness of the steel plate), and the bite should be closely fitted without gaps; For pipes with larger diameter (such as ≥1200mm), stiffeners shall be installed, and the spacing between stiffeners shall be ≤1.5m to prevent pipeline deformation; The processed pipes shall be visually inspected to ensure that the ovality deviation is less than 1% of the pipe diameter and the straightness deviation is less than 1 mm/m..

Pipeline assembly: before assembly, it is necessary to clean up the impurities (such as iron filings and dust) inside the pipeline to avoid blocking the tuyere later; When flange connection is adopted, the flange gasket should be made of materials with good heat resistance and sealing performance (such as rubber gasket and asbestos gasket), and the thickness of the gasket should be 3-5mm, and it should match the flange size. The bolt should be tightened symmetrically and evenly to ensure that the gasket is compacted without leakage; Flexible short pipe (such as canvas short pipe) should be installed at the connection part between the fan and the pipeline, with the length of 150-200mm, so as to reduce the influence of fan vibration on the pipeline, and the flexible short pipe should not be twisted or deformed.

Iii. On-site installation: compliance with specifications and safety

On-site installation should be combined with the underground garage environment, and the installation position, spacing and coordination with other facilities should be controlled.

Bracket installation: Pipe brackets are made of angle steel or channel steel, and the bracket spacing should be determined according to the pipe diameter (such as pipe diameter ≤800mm time interval ≤3m, pipe diameter > 800 mm time interval ≤2.5m), and shall not be installed at tuyeres, air valves and other equipment; Rubber pads should be installed at the contact part between the bracket and the pipeline to prevent the pipeline from being worn; The fixed bracket shall be firmly welded or bolted to the wall and floor, and the bearing capacity shall be more than 1.2 times of the weight of the pipeline (including the weight of the medium), so as to avoid the pipeline from falling due to the looseness of the bracket.

Pipeline hoisting and positioning: when using crane or hand hoist to hoist the pipeline, the hoisting point should be set at the bracket position, and the pipeline should not be directly tied to prevent the pipeline from deformation; The installation height of the pipeline shall meet the design requirements, and the height from the ground shall be ≥2.5m to avoid affecting the garage traffic; When crossing with fire pipes and cable trays, it is necessary to keep a safe distance (the distance between the fire pipes and cable trays is ≥100mm, and the distance between the fire pipes and cable trays is ≥200mm). If the space is limited, it is necessary to install protective plates to prevent the condensate from dripping and damaging other facilities.

Installation of tuyere and air valve: the installation of tuyere should be flush with the wall and ceiling, the edge should be tight and seamless, and the louver of tuyere should be adjusted flexibly; Air valves (such as fire dampers and smoke exhaust valves) should be installed at locations convenient for operation and maintenance, and the distance between the fire dampers and the firewall should be ≤200mm, and they should be linked with the fire protection system to test whether the valves are open and closed normally by electrifying; The tuyere and pipeline shall be connected by soft connection (such as aluminum foil hose) with a length of ≤300mm to ensure smooth airflow and no obvious resistance.

4. Post-inspection and acceptance: ensure that the system meets the standards.

Post-inspection and acceptance is the key to ensure the normal operation of ventilation system, which needs to cover sealing, performance and safety indicators.

Sealing detection: use light leakage method or air leakage test method to detect pipeline sealing. When detecting by light leakage method, put the light source into the pipeline in a dark environment, and observe whether there is light leakage outside the pipeline. If there is light leakage, mark and repair it (such as applying sealant and replacing gasket); The air leakage test shall meet the specification requirements, and the air leakage of the system shall not exceed 10% of the design air volume.

System performance test: start the fan and test the wind speed and air volume of each tuyere to ensure that the deviation between the actual air volume and the designed air volume is ≤ 15%; To detect the running noise of the fan, the noise of the fan in the underground garage shall be ≤85dB(A), and if it exceeds the standard, a muffler or vibration damping device shall be installed; Test the linkage function of fire damper and smoke exhaust valve. When simulating a fire scene, the fire damper should be automatically closed at 70℃ and the smoke exhaust valve should be automatically closed at 280℃, and the signal can be fed back to the fire control room.

Acceptance and rectification: check the overall acceptance according to the design drawings and construction specifications, and check whether the pipeline installation position, bracket spacing and equipment functions meet the requirements; The problems found in the acceptance (such as air leakage, insufficient air volume at the tuyere and valve failure) shall be rectified in time, and the acceptance report shall be signed after the rectification is completed.

On the whole, the installation of ventilation pipes in underground garages should give consideration to safety, standardization and practicality, and the details should be strictly controlled in each step to ensure that the system can meet the requirements of ventilation and smoke exhaust, and can adapt to the special environment of underground garages to ensure long-term stable operation in the later period.