Stainless steel welded air duct is selected for the installation and ventilation project of Jingdong Logistics Warehouse Center.

The selection of stainless steel welded air duct for the ventilation project of Jingdong Logistics Storage Center needs comprehensive consideration from material selection, design planning, construction points, quality acceptance and other aspects to ensure that the ventilation system is efficient and durable and meets the requirements of storage environment. The following is an analysis of key points:

First, the advantages of stainless steel welded air duct adapt to the storage scene

1. Material characteristics meet the storage requirements.

Strong corrosion resistance: there may be dust, humid air or slightly corrosive gas (such as packaging material volatiles) in the storage environment, and an oxide film is formed on the surface of stainless steel (such as 304/316 material), which can resist corrosion for a long time and prolong the service life of the air duct.

High strength and good sealing performance: the welding process makes the air ducts firmly connected, and can withstand the wind pressure of the ventilation system (such as overcoming the pipeline resistance in warehouse ventilation), so as to avoid air leakage affecting the ventilation efficiency, especially suitable for large-size air ducts (such as rectangular air ducts with side length > ＞1000mm).

Clean and environment-friendly: the stainless steel has a smooth surface, which is not easy to accumulate dust and breed bacteria, and meets the storage hygiene requirements (such as ventilation standards for food and medicine warehouses), and can reduce the later cleaning and maintenance costs.

2. Adapt to the characteristics of storage space

Flexible layout: Welded air ducts can be customized in various shapes (round, rectangular and special-shaped) to adapt to the complex building structure of the storage center (such as air ducts inserted between high shelves), and reduce the occupation of storage space through reasonable design.

High temperature resistance and fire prevention: stainless steel has a high melting point (about 1398-1454℃). If the storage involves high temperature environment (such as defrosting and exhaust of cold chain warehouse) or it needs to meet the fire protection code (the air duct needs to be non-combustible material), stainless steel material is more advantageous.

Second, the design planning points

1. Ventilation system demand analysis

Air volume calculation:

Determine the fresh air volume according to the storage area, the storage density of goods and the number of people (for example, according to the Code for Design of Heating, Ventilation and Air Conditioning of Industrial Buildings, the general ventilation frequency of warehouses is ≥6 times /h).

For special areas (such as charging area and equipment room), it is necessary to increase the exhaust air volume to dilute harmful gases (such as CO in forklift tail gas).

Wind pressure matching:

Calculate the resistance along the pipeline (such as duct length and roughness of inner wall) and local resistance (such as elbow and valve), and select the appropriate fan power to avoid poor ventilation effect caused by insufficient wind pressure.

2. Air duct layout optimization

Avoid the working channel: the air duct is installed along the top or wall of the warehouse, away from the shelf operation area, so as to avoid affecting the passage of forklifts and AGV robots.

Zoning control: Independent air systems are set according to storage functional zones (such as storage area, sorting area and storage area), and the air volume in each zone is adjusted through valves to improve ventilation efficiency.

Coordination with the fire protection system: when the air duct passes through the fire protection zone, it is necessary to set fire dampers, and meet the requirements on the fire resistance limit of the air duct in the Code for Fire Protection Design of Buildings (for example, the wall thickness of the air duct passing through the firewall is ≥1.5mm).

Third, the key links of construction and quality control

1. Duct processing and welding

Plate cutting and groove treatment;

Use plasma cutting machine or laser cutting machine to ensure smooth incision. When the side length of rectangular air duct is more than ＞630mm, angle steel flange or reinforcing rib shall be set to prevent deformation.

Before welding, polish the groove (angle 55-65) to remove oil stain and rust, so as to avoid porosity and slag inclusion in the weld.

Welding process requirements:

Argon arc welding or carbon dioxide gas shielded welding shall be adopted to ensure that the weld seam is full and crack-free. After welding, kerosene leakage test (to detect air duct tightness) or negative pressure air leakage test (according to Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Engineering (GB50243) shall be conducted).

When stainless steel comes into contact with carbon steel parts (such as supports), it needs to be isolated with insulating gaskets to prevent electrochemical corrosion.

2. Installation and bracket fixation

Hoisting and support:

The spacing between air duct hangers is ≤3m (≤2.5m when the side length of rectangular air duct is > ＞1000mm), and the brackets are made of hot-dip galvanized angle steel to avoid corrosion caused by direct contact with stainless steel.

When crossing the floor or wall, a sleeve is set, and flexible incombustible materials (such as mineral wool) are filled between the sleeve and the air duct to prevent vibration transmission.

Valve and equipment connection:

The installation positions of regulating valves and check valves should be convenient for operation and maintenance, and flanges or soft connections (such as rubber shock-proof joints) should be used to connect with the air duct to reduce the influence of fan vibration on the air duct.

3. Anti-corrosion and heat preservation treatment

Surface anticorrosion: welding spatter should be polished clean, and non-processed surfaces can be sprayed with special anticorrosive paint for stainless steel (such as epoxy resin paint) to enhance weather resistance.

Insulation layer selection: If the storage center needs temperature and humidity control (such as a constant temperature warehouse), the outside of the air duct is wrapped with centrifugal glass wool or rubber insulation board (thermal conductivity ≤ 0.03 W/(MK)), and the thickness of insulation layer is determined according to the heat load calculation, and it is covered with aluminum foil moisture-proof layer.

Fourth, suggestions on adaptation to Jingdong logistics warehousing scene

1. Intelligent integration

Wind speed sensors and temperature and humidity transmitters are installed at key nodes of the air duct (such as branches and fan inlets), which are connected to WMS to monitor the ventilation state in real time and automatically adjust the fan frequency, thus realizing energy-saving operation.

Combined with the fire protection system, when the smoke detector gives an alarm, the fire damper is closed and the emergency exhaust is started to reduce the risk of fire smoke diffusion.

2. Meet the challenge of high shelf storage

For high-rise shelf warehouses (height > ＞20m), the installation of air ducts needs the help of lift trucks or temporary scaffolding. Before operation, the safety of aerial work equipment shall be checked, and the operators shall wear safety belts and be supervised by designated personnel.

The air duct is routed as far as possible to avoid the shelf roadway and can be arranged along the warehouse column or roof truss to reduce the interference to the operation of automation equipment.

3. Quick installation and minimal disruption

Prefabricated processing (such as the factory completes the segmental welding and numbering of air ducts) and modular assembly on site, which shortens the construction period and reduces the impact on the normal operation of warehousing.

Isolation zones shall be set up in the construction area, and the sign "Do not approach during construction" shall be hung, and sufficient lighting shall be ensured for night operation to avoid conflict with the peak period of storage operation.

V. Acceptance Criteria and Post-maintenance

1. Quality acceptance points

Visual inspection: there is no obvious scratch or deformation on the surface of the air duct, the weld is smooth, the flange is tightly connected, and the insulation layer is not damaged or peeled off.

Performance test:

Air leakage test: air leakage of medium pressure system (such as exhaust pressure > ＞500Pa) is ≤ 0.07 w/(MH), and that of high pressure system is ≤ 0.03 w/(MH).

System debugging: the deviation between the measured air volume and the designed air volume is ≤10%, and the wind speed uniformity of each tuyere meets the design requirements.

2. Maintenance plan

Regularly clean the dust accumulated on the inner wall of the air duct (the cycle is less than or equal to 6 months), and use robots or high-pressure gas for purging to avoid dust accumulation affecting ventilation efficiency or causing fire.

Check the firmness of the bracket and the tightness of the flange bolts, conduct a comprehensive anti-corrosion inspection once a year, and brush the anti-rust paint on the welded parts and corrosive parts.

summary

Jingdong Logistics Warehouse Center chooses stainless steel welded air ducts, which should focus on the storage function requirements, and ensure that the ventilation system meets the requirements of high-efficiency ventilation, corrosion resistance and low maintenance through accurate system design, standardized construction technology and intelligent management, taking into account the safety of storage operations and the operation efficiency of automation equipment, so as to provide reliable guarantee for the stable operation of logistics warehousing.