Characteristics and Application Properties of FRP Winding Process

 

Winding Process

The winding process is to wind the continuous fiber soaked in resin glue onto the core mold according to a certain pattern, and then solidify and demold it to obtain the product. According to the different physical and chemical states of the resin matrix during fiber winding, it is divided into three types: dry winding, wet winding and semi-dry winding. Among the three winding methods, wet winding is the most commonly used.

 

Dry Winding

The biggest feature of the dry winding process is high production efficiency, winding speed can reach 100-200m/h, winding machine is clean, and product quality is high. The disadvantage is that the winding equipment is expensive and pre-impregnated yarn manufacturing equipment needs to be added. Therefore, in addition to the large investment, the interlayer shear strength of the dry winding product is low.

 

Wet Winding

The advantages of wet winding are: the cost is 40% lower than that of dry winding; the product has good airtightness because the winding tension causes the excess resin glue to squeeze out the bubbles and fill the gaps; the fiber arrangement has good parallelism; the resin glue on the fiber can reduce fiber wear; the production efficiency is high; the disadvantages of wet winding are: large resin waste, poor operating environment; difficult to control the glue content and finished product quality; and fewer resin products available for wet winding.

 

Semi-Dry Winding

Compared with the dry method, it eliminates the pre-impregnation process and equipment; compared with the wet method, it can reduce the bubble content in the product.

 

Application Field

Currently, FRP winding products are used in both military and civilian applications. Military products are characterized by high performance and precise winding structure. The main civilian products are storage tanks, pipes and pressure vessels.

 

FRP Storage Tank

For the storage and transportation of chemical corrosive liquids such as alkalis, salts and acids, steel tanks are prone to rot and leakage and have a short service life. If stainless steel is used instead, the cost will be higher and the effect will not be as good as composite materials. The use of fiber-wound underground oil glass fiber reinforced plastic storage tanks can prevent oil leakage and protect water sources. Double-wall composite fiber-reinforced plastic storage tanks made by fiber-wound technology have been widely used in gas stations.

 

 

FRP Pressure Vessels

FRP pressure vessels are mostly used in military applications, such as solid rocket engine casings, liquid rocket engine casings, FRP pressure vessels, deep-water external pressure casings, etc. At present, there are corresponding standards and specifications for the application of FRP winding technology on solid rocket engine casings.

 

 

Characteristics

Among them, FRP pipe tanks have some excellent performance characteristics, which are analyzed and described as follows to promote the development of FRP pipe tanks;

 

Good Corrosion Resistance

Metal pipe tanks are very easy to react with the medium when transporting chemicals, while the wound glass pipe tank is structurally divided into an inner lining layer and a protective layer. Whether the medium corrodes the pipe tank mainly depends on this. Corrosion can be avoided by carefully selecting the medium used for the inner lining layer and the outer protective layer.

 

LightWeight and Easy To Transport

The density of wound FRP pipe tanks is only 1/4-1/5 of that of steel products. Although its wall thickness is slightly thicker than that of steel products of the same specification, its total weight is lighter. The light weight not only saves fuel consumption during transportation, but also reduces the requirements for traffic roads, and the loading and unloading and installation processes are also faster.

 

Low Thermal Conductivity and Good Insulation Effect

The thermal conductivity of wound FRP is much lower than that of steel products. In addition, the wall of FRP products is thicker, and the insulation effect is particularly obvious. The use of FRP pipe tanks can significantly reduce the insulation cost.

 

Flexible Connection Methods

There are many connection methods for FRP pipes and accessories, mainly including: flat end butt joint, flange connection, threaded connection, etc., which can be flexibly selected according to specific construction conditions.

 

Good Electrical Insulation and Anti-Puncture

The resistivity of FRP pipe tanks is higher than that of steel products. They are insulators and can be safely used in areas with dense power transmission and wire routes or frequent thunderstorms.

 

Strong Designability

The winding angle during winding can be designed, the wall thickness can be designed, the material can be designed, the joint can be designed, and the product shape can be designed.