Brief Introduction of valve anti-corrosion lining materials

Brief introduction of valve anti-corrosion lining materials (F4/F46/PFA/PO, etc.)

1. Polytetrafluoroethylene PTFE (F4)

Polytetrafluoroethylene (Teflon or PTFE), commonly known as "Plastic King", is a polymer compound formed by polymerization of tetrafluoroethylene. It has excellent chemical stability, corrosion resistance, sealing, high lubricating Insulation and good aging resistance.

Applicable medium: strong acid, strong alkali, strong oxidant, etc.; operating temperature -200～180℃;

Features: It has excellent chemical stability, high heat resistance and cold resistance; low friction coefficient, it is an excellent self-lubricating material, but has low mechanical properties, poor fluidity and large thermal expansion.

Polytetrafluoroethylene (F4, PTFE) has a series of excellent performance: 

high temperature resistance - long-term use temperature of 200~260 degrees, 

low temperature resistance - still soft at -100 degrees; 

corrosion resistance - resistance to aqua regia and all organic solvents; 

Weather resistance—best aging life among plastics; 

high lubricity—with the smallest coefficient of friction (0.04) among plastics; 

non-stick—with the smallest surface tension among solid materials without sticking to anything; 

non-toxic—with physiological inertness; 

Excellent electrical properties, it is an ideal Class C insulating material, a thick layer of newspaper can block high voltage of 1500V; it is smoother than ice. 

PTFE materials are widely used in important departments such as national defense and military industry, atomic energy, petroleum, radio, electrical machinery, and chemical industry. Products: PTFE rods, tubes, sheets, turned sheets.

2. Polyperfluoroethylene propylene FEP (F46)

Fluoroplastic 46, the English name is Hexafluoropropene-tetrafluoroethylene copolymer, the CAS number is 25067-11-2, the molecular formula is (C3F6·C2F4)x, it is copolymerized by tetrafluoroethylene and hexafluoroethylene, and is used to make electronic insulation parts and wires Insulation layer, chemical pump, corrosion-resistant lining of valve, anti-stick sleeve of light textile industry drum, etc.

Applicable medium: any organic solvent or reagent, dilute or concentrated inorganic acid, alkali, ketone, aromatic hydrocarbon, chlorinated hydrocarbon, 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.

3. Soluble polytetrafluoroethylene (PFA)

The English name of PFA is: Polyfluoroalkoxy, the Chinese name is: tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer (also known as: perfluoroalkyl compound, soluble polytetrafluoroethylene).

The chemical properties of PFA FEP PTFE are similar, but FEP can only be used below 200 degrees, and PTFE cannot be injected. PFA has a melting point of about 580F and a density of 2.13-2.16 g/cc (grams per cubic centimeter). PFA is similar to PTFE and FEP, but has slightly better mechanical properties than FEP above 302T, can be used at temperatures up to 500F, and has comparable chemical resistance to PTFE. The product forms of PFA are granular products for molding and extrusion, powder products for rotational molding and coatings; its semi-finished products are films, sheets, rods and pipes.

4. Polyolefin (PO)

PO material, also known as P0 material or P0 plastic, is a polyolefin copolymer, the English name is polyolefin (referred to as P0); polyolefin, as the name suggests, is a polymer made from olefin monomers. Synthetic materials such as propylene and ethylene can be called polyolefins. Commonly used polyolefins are polypropylene, polyethylene, EVA, POE and so on. For example, in the south, HDPE material is used to be called PO material, commonly known as low pressure material. Applicable medium: various concentrations of acid and alkali salts and some organic solvents; 

operating temperature: -58 ~ 80 ℃;

Features: It is the most ideal anti-corrosion material in the world at present, and has been widely used in the lining of large-scale equipment and pipe fittings for rotational molding.

Steel-lined fluoroplastic valves usually use the above four materials, and the following materials are usually all-plastic lining valve fittings. The overview is for a simple understanding.

5. Polytrifluoroethylene PCTEF (F3)

Applicable medium: various organic solvents, inorganic corrosive liquids (oxidizing acids);

Operating temperature: -195～120℃;

Features: Heat resistance, electrical properties and chemical stability are second only to F4, mechanical strength, creep properties and hardness are better than F4.

6. Polyvinylidene fluoride PVDF (F2)

Applicable medium: resistant to most chemicals and solvents;

Operating temperature: -70～100℃;

Features: Tensile strength and compressive strength are better than F4, bending resistance, weather resistance, radiation resistance, light resistance and aging, etc. The biggest feature is good toughness and easy molding.

7. Polypropylene RPP

Applicable medium: aqueous solution of inorganic salt, dilute or concentrated solution of inorganic acid and alkali;

Operating temperature: -14～80℃;

Features: One of the lightest plastics, its yield, tensile and compressive strength and hardness are better than low-pressure polyethylene, with outstanding rigidity; good heat resistance, easy to form, and inexpensive. After modification, the dynamic impact, fluidity and flexural modulus of elasticity are improved.

8. Polyvinyl chloride (rigid) PVC

Applicable medium: water resistance, concentrated alkali, non-oxidizing acid, chain hydrocarbon, oil and ozone, etc.;

Operating temperature: 0～55℃;

Features: High mechanical strength, excellent chemical stability and dielectric properties, good oil resistance and aging resistance, easy welding and bonding, and low price.

All kinds of lined pipeline valves have the same housing and connection dimensions with the same nominal diameter, but the lining materials can be used in the following different lining materials according to different media: modified polyolefin PO, polypropylene RPP, polyperfluoroethylene propylene F46 , Teflon F4, Teflon F3, Polyvinylidene F2.