With the development of phenolic epoxy vinyl ester resin, FRP device has been widely used in wet flue gas desulfurization system, such as slurry spray pipe made of FRP, etc.
1. Winding and bonding
The FRP slurry spray pipe used in the wet FGD project is usually manufactured by sections and parts in order to facilitate transportation in the manufacturing process. When it is installed on site, the winding and bonding process is used to connect the parts. At present, the connection between the slurry nozzle and the FRP spray pipe is basically changed from the previous flange connection to the winding bonding process. The winding bonding process has the advantages of high connection strength, no leakage, simple process, convenient construction and low cost.
The specific size of glass fiber surface felt can be determined according to the actual pressure and diameter. Due to the high thermal expansion rate of FRP, it is required to measure, cut, assemble and bond at the same ambient temperature during construction, and prepare the required glass fiber reinforcement materials, resin mastic, sheet resin, surface resin and contact agent in advance.
2 structure of winding layer
The outer surface structure of the winding part shall be consistent with the outer surface of the pipe, and the performance of the * * winding part shall be consistent with the overall performance of the pipe. In addition, in order to prevent the slurry from causing corrosion to the butt end face of the pipeline, the butt joint needs to be filled with resin mastic, and the resin requirements for the configuration of the mastic are the same as that of the pipeline resin. If necessary, wax the outer layer of * * to prevent air from entering and cracking (cracking).
The winding layer structure is divided into three parts from the outside and the inside:
Wear resistant layer: this part belongs to * * outer layer structure of winding layer, which is composed of glass fiber surface felt, resin and wear-resistant filler, mainly for corrosion resistance and wear resistance. This layer of glass fiber surface felt: resin: wear-resistant filler: 1:57:38 (mass ratio), thickness about 0.5mm.
Corrosion resistant layer: this part is composed of resin rich layer and intermediate layer, glass fiber surface felt and resin, forming * * high corrosion resistance, under the wear-resistant layer. The resin content of rich resin layer is more than 90%, and the thickness is about 0.5mm; the resin content of middle layer is 70% ~ 80%, and the thickness is about 2.0mm.
Reinforcement layer: this part is directly wound on the outer wall of the pipeline, and is mainly designed to bear the pressure and other loads. Its thickness is determined according to the load conditions according to formula (1). The resin content of this layer is 30% - 40%, which is composed of glass fiber, chopped fiber mat and resin.
3 inspection of winding layer
After the winding and bonding construction is completed, the winding layer shall be inspected according to the requirements of Hg / t20696-1999 code for design of FRP chemical equipment. If there is no delamination, delamination, crack, craze, fiber exposure, dry spot, inclusion, bubble, small hole, resin tumor and other defects, it is qualified.