Advantages and Disadvantages of Various Lining Materials

1. Rubber Lining (Soft Lining, Widest Application)

1.1 Natural Rubber:

Characteristics: Good elasticity, wear resistance, erosion resistance, resistant to weak acids and alkalis, poor aging resistance.

Applications: Wastewater containing silt, slurry, seawater, freshwater, neutral water at room temperature; mostly used in slurry applications.

1.2 Butyl Rubber (IIR):

Core Advantages: Resistant to strong inorganic acids, resistant to chloride ion penetration, excellent airtightness.

Operating Temperature: -30～90℃

Applications: Concentrated hydrochloric acid, dilute sulfuric acid, hydrofluoric acid, brine, chlorine-containing aqueous solution, brine, wastewater containing chloride ions; pickling pipelines, brine valves in the chlor-alkali industry.

Contraindications: Nitric acid, strong alkalis, aromatic solvents.

1.3 Chloroprene Rubber (CR):

Ozone resistant, seawater resistant, resistant to weak acids, wear resistance superior to natural rubber.

Applications: Seawater, seawater desalination, saline wastewater, mild acid and alkali media.

1.4 Ethylene Propylene Diene Monomer (EPDM) Rubber: 

Resistant to acids and alkalis, steam, aging, and hot water; not resistant to oils.

Temperature: -50～120℃

Applications: Hot water, steam, pure water, weak acids and alkalis, drinking water, food processing water, high-temperature water bodies for wastewater treatment; HVAC hot water valves, pure water systems.

1.5 Fluororubber (FKM): 

A high-temperature resistant and corrosion-resistant rubber material, resistant to acids and alkalis, oils, and some solvents.

Suitable for high-temperature acids and alkalis, oily acid and alkali waste liquids, maximum temperature 180℃, high cost.

2. Fluoroplastic Lining (Corrosion-resistant Ceiling Panels, Mainstream in Strongly Corrosive Chemicals)

2.1 PTFE (Polytetrafluoroethylene):

Features: Resistant to almost all strong acids and alkalis, strong oxidants, and organic solvents; non-stick to media; Disadvantages: High cold flow rate, low hardness, not resistant to negative pressure, poor thermal conductivity.

Operating temperature: -60～180℃

Applications: Hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, caustic soda, aqua regia, organic solvents, and highly corrosive chemical media of any concentration; valves for strong acids and alkalis in chemicals, pesticides, and fine chemicals.

Limitations: Prone to collapse and deformation under vacuum negative pressure conditions; not suitable for high-speed scouring of hard granular slurries.

2.2 FEP Fluorinated Ethylene Propylene (F46):

Modified PTFE, can be hot-melt molded, no cold flow issues, better toughness, and superior weldability compared to PTFE.

Temperature: -60～150℃, operating conditions are basically the same as PTFE, commonly used in negative pressure valves and lined diaphragm valves.

2.3 PFA Soluble Polytetrafluoroethylene:

Performances are very close to PTFE, can be melt-processed, excellent toughness, resistant to negative pressure, creep resistant, and high temperature resistant.

Temperature: -60～200℃

Applications: High-temperature highly corrosive media, high-purity reagents, high-purity semiconductor chemicals, negative pressure corrosion conditions; preferred for high-purity chemicals.

2.4 ETFE (Ethylene Tetrafluoroethylene, F40):

High hardness, wear-resistant, erosion-resistant, negative pressure resistant; mechanical strength far exceeds PTFE.

Temperature: -60～150℃

Applications: Corrosive slurries containing fine solid particles, mineral slurries, pickling slurries, high-speed erosion corrosive media; hydrometallurgical, tailings slurry valves.

3. General-purpose plastic linings (economical corrosion protection)

3.1 PP (Polypropylene):

Resistant to weak acids, weak alkalis, and salt solutions; not resistant to concentrated strong oxidizing acids (concentrated nitric acid, concentrated sulfuric acid).

Temperature: ≤80℃

Applications: Room temperature dilute acid and alkali wastewater, electroplating wastewater, brine, food wastewater; low-cost civilian corrosion-resistant valves.

3.2 PVC/CPVC:

PVC is resistant to dilute acids at room temperature; CPVC is resistant to high temperatures (≤95℃); however, it is not resistant to ketones and ester solvents.

Applications: Electroplating industry, handling hydrochloric acid at room temperature, pickling wastewater, and chemical wastewater.

3.3 PVDF (Polyvinylidene Fluoride):

Resistant to acids and alkalis, resistant to some solvents, wear-resistant, and high-strength.

Temperature: -40～130℃

Applications: Lithium battery electrolytes, fine chemical corrosive media, and fluids containing small amounts of particulate matter.