Lined valves adopt the lining process for all the places where the medium in the valve body can reach. The lining materials are generally made of fluoroplastics such as FEP (F46) and PCTFE (F3), which can be applied to various concentrations of sulfuric acid, hydrochloric acid, hydrofluoric acid, and Various organic acids, strong acids, strong oxidants, and other corrosive media pipelines, but the fluorine-lined valves are subject to relatively large temperature limitations (only suitable for media between -50°C and 150°C), and it is possible to make fluorine-lined valves. Plastic valves include fluorine-lined butterfly valve, fluorine-lined ball valve, fluorine-lined globe valves, fluorine-lined diaphragm valves, fluorine-lined gate valves, fluorine-lined plug valves, etc.
Commonly used lining materials include the following:
1. Polyperfluoroethylene FEP (F46) applicable medium:
Any organic solvents or reagents, dilute or concentrated mineral acids, bases, ketones, aromatic hydrocarbons, chlorinated hydrocarbons, etc.
Operating temperature: -85~150℃
Features: Mechanical, electrical properties and chemical stability are basically the same as F4, but the outstanding advantages are high dynamic toughness, excellent weather resistance and radiation resistance
2. Polytrifluoroethylene PCTEF (F3)
Applicable medium: various organic solvents, oxidizing acids
Operating temperature: -195~120℃
Features: Compared with PTFE, the heat resistance, electrical properties and chemical stability are slightly worse, but the mechanical strength, creep performance and hardness are better
3. Polypropylene: RPP
Applicable medium: aqueous solution of inorganic salts, dilute or concentrated solutions of inorganic acids and alkalis
Operating temperature: -14~80℃
Features: One of the lightest plastics, its yield, tensile and compressive strength, hardness are better than low-pressure polyethylene, rigidity, good heat resistance
4. Polyvinyl chloride: hard PVC
Applicable medium: resistant to water, concentrated alkali, non-oxidizing acid, chain hydrocarbon, oil and ozone, etc.
Use temperature: 0-55℃
Features: low price, good chemical stability and dielectric properties, good mechanical strength, oil resistance and aging resistance, easy to process and shape
5. Polytetrafluoroethylene PTFE (F4)
Use medium: strong acid, strong alkali, strong oxidizing agent, etc.
Operating temperature: -200~180℃
Features: Excellent chemical stability, high heat resistance, cold resistance, low friction coefficient, excellent self-lubricating material, but low mechanical properties, poor fluidity, large thermal expansion
6. Polyvinylidene chloride PVDF(F2)
Use medium: resistant to most chemicals and solvents
Operating temperature: -70~100℃
Features: Tensile strength and compression strength are better than PTFE, the biggest feature is good toughness, easy processing and forming
7. Polyolefin: PO
Applicable medium: various concentrations of acid-base salts and certain organic solvents
Operating temperature: -58~80℃
Features: It is the most ideal anti-corrosion material in the world, and has been widely used in the lining of large-scale equipment and pipe fittings for rotational molding