Corrosion Resistance of PTFE Packing
Briefly introduces the strong corrosion resistance and applications of PTFE packing.
Corrosion Resistance of PTFE Packing
Polytetrafluoroethylene (PTFE) is the most corrosion-resistant material among plastic fillers, earning it the title of "King of Plastics." It maintains extremely high chemical inertness in almost all chemicals, and its corrosion resistance range far exceeds that of other plastics such as PVDF and PP.
Material Characteristics
Features | Parameters |
Operating Temperature | -200℃ to 260℃ |
Density | 2.1-2.2 g/cm³ |
Mechanical Strength | Low (reinforcement required) |
Coefficient of Friction | Extremely Low |
Corrosion Resistance
PTFE is virtually unaffected by any chemicals:
Corrosion Resistance Range: Concentrated sulfuric acid (98%), concentrated nitric acid (>60%), aqua regia, fuming sulfuric acid, hydrofluoric acid, strong alkalis, aromatic hydrocarbons, chlorinated hydrocarbons, ketones, esters, oxidants (chlorine, ozone), and almost all salts.
Only not resistant to: molten alkali metals and high-temperature chlorine trifluoride.
Medium | PP | PVDF | PTFE |
Concentrated Sulfuric Acid (98%) | No | No | Yes |
Aqua Regia | No | No | Yes |
Fumigating Sulfuric Acid | No | No | Yes |
Key Limitations
Low mechanical strength; pure PTFE is easily deformed, requiring fiber reinforcement.
Strongly hydrophobic surface; difficult liquid film spreading; low mass transfer efficiency.
Extremely high cost (10-20 times that of PP).
Large coefficient of thermal expansion; expansion space required.
Typical Applications
Fumigating sulfuric acid systems
Concentrated nitric acid (>60%) treatment
Aqua regia contact equipment
Ultra-low temperature conditions (below -100℃)
Selection Recommendations
Operating Conditions | Recommendation |
Concentrated sulfuric acid, fuming sulfuric acid | PTFE |
High-temperature hydrochloric acid, wet chlorine (<150℃) | PVDF |
General acids and alkalis, organic solvents (<100℃) | PP |
Summary
PTFE packing's performance can be described as follows: top-tier corrosion resistance (withstanding aqua regia and fuming sulfuric acid), and an extremely wide temperature range (-200℃ to 260℃), but it has low mechanical strength and extremely high cost. It is only used in extremely corrosive media that even PVDF cannot withstand, serving as a "last resort" among plastic packings. For the vast majority of corrosive conditions, PVDF can meet the requirements and offers better cost-effectiveness.