【Haichuan Construction Technology】Construction Technology for Inner-insulated Metal Ducts
Thread Content
Inner-insulated metal ducts are produced by attaching insulation material to the inner wall of traditional galvanized thin-steel-plate flanged ducts; the diameter of the duct is determined by the inner diameter after the insulation material is attached, and full-automatic production is achieved through CNC production lines. The use of this technology eliminates the need for on-site insulation work on air ducts, thereby improving the efficiency of air duct installation at the site. Moreover, the air ducts are manufactured using fully automated production lines, ensuring consistent product quality. Scope of application: Suitable for the fabrication and installation of air ducts in low- and medium-pressure air conditioning systems, excluding clean air conditioning systems and smoke control systems.
Technical details: Construction process. Compared to the standard manufacturing process for flanged ducts made from thin steel plates, after the duct joints are formed and the flanges are shaped, three additional steps are required to apply the internal insulation material: spraying glue, applying cotton, and driving nails. After that, the sheets are bent and joined together; all other steps remain identical in both cases. These three processes have been integrated into a complete production line, resulting in a production efficiency almost on par with that of thin-steel plate flanged ducts. To prevent the insulation material from being dispersed, it is required that the adhesive coating coverage on the inner wall of the metal ducts be over 90%, and the airflow velocity inside the ducts must not exceed 20.3 m/s. In addition, the construction of internally insulated metal air ducts has the following key points, as shown in the table below. 1. Before installing the lining for the air duct, it is first necessary to check whether there are any damages to the coating on the duct lining or if it is contaminated. If such issues are found, repairs must be carried out or a section of intact duct should be used for installation. 2. The installation of lined air ducts follows a process similar to that of thin-steel-plate flanged air ducts: first, the supports and hangers for the air ducts are installed, with the spacing between them being determined in accordance with relevant regulations. The air ducts can be lifted section by section depending on the actual conditions on site, or they can be assembled on the ground over a certain length before being lifted as a whole. 3. When connecting internal insulation air ducts to external insulation air ducts, equipment, and air valves, etc., the flange height can be adjusted according to the requirements in the table on the previous page, or elbow connections can be used. 4. After the installation of the air ducts is complete, a leak rate test should be conducted. It should be noted that the main factors leading to inadequate airtightness of the air ducts are the misalignment of the wind-blocking strips with the flange edges, as well as the use of flange gaskets of inappropriate width or improper application of those gaskets. 5. During the transportation and installation of air ducts, care should be taken to prevent moisture and dust.
Technical specifications: 1. The strength and airtightness requirements of the ductwork system shall meet the provisions of the \"Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Engineering\" GB50243； 2. The thermal insulation and fire resistance performance requirements for duct systems shall meet the specifications set out in the \"Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Projects\" GB50243 and the \"Technical Regulations for Ventilation Ducts\" JGJ141, respectively ； 3. For the fabrication and installation of insulated metal air ducts, reference shall be made to the relevant provisions in the **Building Standard Design Manual: Fabrication and Installation of Non-metallic Air Ducts 15K114** ； 4. The insulation cotton for the lining and its surface coating shall be made of non-flammable materials, and the adhesives used should be environmentally friendly and non-toxic.
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