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Commonly used materials for chemical equipment-the characteristics of graphite materials
- 2020-06-15-

Commonly used materials for chemical equipment-the characteristics of graphite materials

The technological conditions of the chemical production process are very complicated, the pressure ranges from vacuum to high pressure or even ultra high pressure; the temperature ranges from cryogenic to high temperature; the medium is corrosive, flammable, explosive, toxic and even highly toxic.

In order to ensure the safe operation of chemical equipment, the design has high requirements on the reliability of the selected chemical equipment materials. Commonly used materials for chemical equipment can be divided into two categories: metal and non-metal. Among them, the most widely used are metal materials. There are many factors to consider when selecting materials.

The general requirements for materials are as follows:

①Should have sufficient strength and rigidity; good plasticity and toughness.
②It has certain corrosion resistance in the medium.
③Good processing performance
④ Extensive resources, sufficient supply and reasonable economy.

Graphite materials include natural graphite and artificial graphite.
Natural graphite mineral has a large impurity content and is not easy to select. It can be used as surface coating and colloidal lubricant.
Artificial graphite is made of impermeable graphite after special processing (such as carbonization and graphitization with organic materials). It is made of general artificial graphite products as the matrix and impregnated with resin to fill the pores in the matrix, or graphite powder and resin are used for adhesion. Binder, pressed or cast, also called plastic graphite.
Impermeable graphite has the characteristics of superior corrosion resistance, good thermal conductivity, low linear expansion coefficient, strong thermal shock resistance, and good processing performance; but it is low in strength and brittle. Commonly used in chemical equipment, such as block, tube and radialGraphite heat exchanger, Falling film graphite absorber, concentrated sulfuric acid graphite diluter, graphite synthesis furnace and corrosion-resistant pipes, pipe fittings and bed plates, graphite explosion-proof discs, etc.
The chemical properties of impermeable graphite vary with the performance of the impregnating resin. In addition to strong oxidizing media and strong alkalis, phenolic impregnated graphite is resistant to corrosion by various organic acids, inorganic acids, salt solutions and various organic solvents. Furan resin impregnated is more resistant to alkalis and strong oxidizing acids. Polytetrafluoroethylene impregnated graphite Can withstand the corrosion of various media.