1) first release agent coated on the die forming surface (or die in the outer surface of a layer of transparent glass paper), to be fully dry, plus there will be the initiator (or curing agent) and accelerant additive evenly on the mold surface, then put the cut glass cloth in the upper berth. Then apply the magnesium oxychloride cement on the paved glass cloth and take care to remove the bubbles. A good coating of magnesium oxychloride cement paste then with cut glass cloth, so the operation is repeated, until it reaches the design and specification of thickness.
2) the wind pipe surface thickness of the slurry to flatten the glass fiber mesh cloth texture is appropriate (see:). No dense air holes and grout leaks are allowed on the wall of the pipe to avoid the stress concentration under the bending tensile stress (positive air pressure) and the bending compressive stress (negative wind pressure).
3) there is a transition arc between the pipe body and the flange corner, and the transition arc radius should be 0.8 to 1.2 times the wall thickness, so as to improve the carrying capacity of flange and avoid stress concentration in the cantilever state. Fiberglass mesh shall be extended to the duct at the flange of the duct.
4) glass fiber mesh length and width must take the overlapping method is not enough, in order to improve joint tangential bearing capacity, so as to effectively overcome the radial tensile stress, bending stress and bending shear stress. The lap length of the glass fiber cloth at the joint is generally 50 to 100mm, and the joint of each glass fiber cloth should be at a certain distance from the adjacent joint. The longitudinal and transverse joints between adjacent layers shall be greater than 300mm, and the distance from the same seam shall not be less than 500mm.
5) paste made of circular duct, glass cloth along the radial 45 degree angle to the direction of cut cloth; conical paste products, according to the fan-shaped cloth.
6) when the length of the rectangular duct is greater than 900mm and the length of the pipe is greater than 1250mm, the reinforcement of the duct shall be strengthened. The reinforcement shall be made of bulk material (fiber reinforced plastic) and reinforced plate at the maximum stress, so as to increase the modulus of the section and increase the overall strength of the tube. Strengthening wind pipe is also available in duct production after treated by metal or other corrosion resistant material for reinforcement, the reinforcement should be integrated with the wind pipe, and the same body of cementitious materials and the wind pipe plugging slot.