Impermeable graphite is an ideal material with good corrosion resistance and thermal conductivity in chemical production. It can be used to make heat exchangers, reaction tanks, absorption towers, gas combustion towers, hydrochloric acid synthesis furnaces, graphite centrifugal pumps, jet pumps, and various pipelines and joints. Impermeable graphite is divided into three categories:

1. Impregnated impermeable graphite products - This is made by impregnating the graphite matrix. Impregnating agents not only reduce the porosity of graphite, but also increase the compressive strength and tensile strength of graphite materials by 1-2.5 times and 4-5 times respectively; Increase bending strength by 2-3 times; Increase the impact strength by 2-2.5 times. Commonly used impregnating agents include phenolic resin, furfural ketone resin, furfural alcohol resin, organic silicon resin, water glass, paraffin, divinylbenzene, asphalt, etc.

2. Pressed impermeable graphite product - is a material made by mixing artificial graphite powder and synthetic resin in a certain proportion and forming it under a certain pressure. The mechanical strength of this product is 1-1.3 times higher than that of pure carbon graphite materials and impregnated graphite materials. Its disadvantage is that its thermal conductivity is only 1/3 of that of impregnated graphite material, and its linear expansion coefficient is large. This material can be made into pipes, plates, tees, pumps, etc.

3. Pouring impermeable graphite products - This is made by using thermosetting resin as the adhesive, graphite powder as the filler, adding a hardening agent, and pouring at room temperature (or heating) and normal pressure. This product has good chemical stability, heat resistance, and high compressive strength. Its disadvantages are low impact strength, poor thermal conductivity, and high brittleness. Mainly used for manufacturing pump casings, pump impellers, three-way valves, pickling tanks, etc.