In ventilation engineering construction, the installation of air duct is a major point, and the correct installation method should be paid attention to when installing air duct:
1. Find out the position and direction of the air duct according to the design drawings, and determine the bottom elevation of the air duct with reference to the reference line given by civil engineering.
2, after the elevation is determined, according to the location of the duct space and the surrounding environment, determine the duct, hanging, bracket form.
3. Setting lifting points: according to the form of hanger, arrange lifting points, and install boom and crosspiece bracket with expansion bolts. Supports and hangers shall not be installed in tuyeres, valves, inspection holes, etc. , so as not to interfere with the operation, hanger shall not be directly hung on the flange.
4. The air duct to be installed is connected to the ground for a certain length, and then hoisted in place; You can also put the air duct on the bracket section by section and connect it section by section. General installation sequence is main pipe first, then branch pipe.
5, when in place on the duct bracket, should dial the position, adjust the horizontal and vertical duct, and then fixed according to the requirements of atlas.
Second, the air duct installation matters needing attention
1, when the air duct is connected to the fan, soft connectors should be added at the air inlet and air outlet, and the cross-sectional dimensions of the soft connectors should be consistent with the air inlet and air outlet of the fan. Hose joints can generally be made of canvas, artificial leather and other materials. The length of the hose is not less than 200, and the tightness is appropriate. The flexible hose can buffer the vibration of the fan.
2. Before the air duct is connected with dust removal equipment and heating equipment, it should be prefabricated and installed according to the actual surveying and mapping drawings after the equipment installation is completed.
3. When the air duct is installed, the inlet and outlet should be opened when the air duct is prefabricated. If it is necessary to open an air outlet on the installed air duct, the interface should be tight.
4. When conveying gas containing condensed water or high water content, the horizontal pipeline should be provided with a slope and connected with a drainage pipe at the low point. When installing, there should be no longitudinal seam at the bottom of the air duct, and the bottom seam should be sealed.
5. For the steel plate air duct conveying flammable and explosive gases, jumpers should be installed at the connecting flange of the air duct and connected with the electrostatic grounding grid.
Three, duct installation specification requirements?
1. Before installing the air duct, check the drawings with the construction site to see if it can be installed according to the design elevation and position.
2, using infrared positioning pay-off, ensure the spacing and straightness of the air duct, and according to the center line of the air duct, find out the installation position of the hanger and install the hanger.
3. After the dimensions and angles of each part of the air duct system are confirmed, the assembly and installation shall be started. The connection of air ducts should be straight and without distortion, and the nuts of connecting flanges should be on the same side.
4. The gasket between the air duct and the air duct flange shall be made of heat-resistant rubber sheet with a thickness of 3 mm or more. Gaskets shall not extend into the pipeline or protrude from the flange. Gaskets shall not contain asbestos and other harmful components, and shall be resistant to oil, moisture and acid and alkali corrosion.
5. When installing the air duct, the center line of the air duct must be kept horizontal. After installing a section of air duct, use a level meter to measure the level; When the length of air duct exceeds 20m, anti-sway brackets must be set, with at least one pair for each system.
6. When the air duct passes through the fire-proof and explosion-proof wall or floor to be closed, an embedded pipe or protective sleeve shall be set, and the thickness of the steel plate is 2mm. Between the air duct and the protective sleeve, flexible materials which are non-combustible and harmless to human body should be used for plugging.
7, the installation of all kinds of duct parts and operating mechanism, first check whether the valve shape and operating mechanism are in good condition, check the flexibility of action, confirm that the valve is normal in all aspects before installation, the installation direction and position should be correct, and the valve operating mechanism side should have at least 350mm of net space for operation and maintenance; Fire dampers on both sides of the fire partition wall should not be more than 200mm away from the wall.
8. The supports and hangers of fire prevention and smoke exhaust pipes must be set separately, and the supports and hangers of branch pipes, pipe silencers, muffler elbows and fire dampers must be set separately.
9. After the installation of air duct, leak test shall be conducted according to the system pressure grade.