The structure of FRP tank mainly includes the following parts:
Inner lining layer: The inner lining layer is the innermost layer of FRP tank, which has the function of airtightness and inner frame. Its thickness is usually 2.5~3mm, and it uses resins with good toughness, high elongation and low curing shrinkage, such as bisphenol A type unsaturated polyester resin or vinyl ester resin. The reinforcing materials are glass fiber surface felt, glass fiber chopped strand felt and glass fiber untwisted yarn, etc. The inner lining layer can also be divided into inner surface layer, sub-inner layer and inner lining outer layer.
Strength layer: The strength layer is the main bearing layer of the tank body and is formed by winding process. This layer is wound by glass yarn and uses high-strength and high-toughness resins, such as general-purpose unsaturated polyester resin. Its thickness is determined according to the diameter, pressure and safety factor of the tank body.
Exterior layer: The exterior layer is located at the outermost layer of the tank body, with a thickness of about 0.5mm. It has the effects of anti-aging and anti-ultraviolet radiation, and prevents the infiltration of external media. This layer uses unsaturated polyester resin with excellent weather resistance, and the resin content is greater than 80%.
Top cover: The top cover of the FRP vertical tank cannot be too thin. It is usually designed according to a uniform load of 1kPa, and vertical and horizontal cross reinforcement ribs are appropriately arranged to prevent local collapse of the top cover.
Tank wall thickness: The tank wall gradually thickens from the top to the bottom of the tank. The bottom reinforcement ring not only strengthens the bottom cylinder of the tank, but also serves as an anti-seepage structure. The wall thickness at the top of the tank is generally no more than 5mm. The use of a gradient thickness vertical tank can reduce the material consumption by 30%.