When to Use PFA-Lined Valves
A Practical Guide to Material Selection for Corrosive Industrial Applications
Selecting the right valve material for corrosive service requires matching material capabilities to actual process conditions. This guide provides practical criteria for specifying PFA-lined valves versus alternatives—focusing on real-world operating limits, not theoretical material properties.
Operating Temperature and Pressure Limits
PFA (Perfluoroalkoxy) as a material can withstand temperatures up to 260°C in laboratory conditions. However, practical valve operating limits are significantly lower due to differential thermal expansion between metal body and PFA liner, seal and seat performance at elevated temperatures, and pressure capability reduction at higher temperatures.
GFT9 Body Material Options:
Our PFA-lined valves are available with two body materials, each suited to different operating conditions:
Cast Carbon Steel (1.0619)
Our standard body material for most industrial applications. Operating range from -20°C to +180°C. Excellent for general chemical service, mining, pulp and paper, and water treatment applications. Available in standard and high-pressure configurations.
Stainless Steel (1.4408)
Our premium body material for extended temperature range and applications requiring enhanced corrosion resistance of the valve exterior. Operating range from -60°C to +180°C. Preferred for clean room environments, pharmaceutical applications, semiconductor manufacturing, and cryogenic service.
Pressure-Temperature Relationship:
Operating pressure capability decreases as temperature increases. Refer to GFT9 pressure-temperature diagrams for specific ratings at your operating conditions. At maximum temperature ratings, pressure capability is reduced from nominal PN values.
Key Point: When evaluating PFA-lined valves, use these practical valve ratings—not theoretical PFA material limits.
Applications Where PFA-Lined Valves Excel
PFA-lined valves provide significant advantages in specific application categories:
Strong Mineral Acids
PFA provides complete resistance to:
• Hydrochloric acid (HCl) – all concentrations
• Sulfuric acid (H₂SO₄) – all concentrations to 98%
• Nitric acid (HNO₃) – all concentrations to 70%
• Phosphoric acid (H₃PO₄) – all concentrations
• Hydrofluoric acid (HF) – the only common polymer fully resistant
Stainless steel corrodes rapidly in these acids; PFA provides extended service life.
Strong Bases and Caustics
• Sodium hydroxide (NaOH) to 50% at temperatures to 120°C
• Potassium hydroxide (KOH)
• Ammonium hydroxide
Hot caustic attacks many polymers; PFA maintains integrity.
Oxidizing Agents
• Chlorine dioxide (ClO₂) – primary advantage over stainless steel
• Sodium hypochlorite (NaOCl)
• Hydrogen peroxide (H₂O₂)
• Wet chlorine and bromine
PFA resists oxidizing attack that causes stress corrosion cracking in stainless steel.
Mixed Chemical Service
Multipurpose plants handling varying chemicals benefit from PFA's universal resistance—one material handles acids, bases, solvents, and oxidizers without equipment changes.
High Purity Requirements
PFA's non-porous surface prevents absorption and contamination:
• Semiconductor manufacturing
• Pharmaceutical production
• Ultrapure water systems
Applications: Where Other Materials May Be Appropriate
PFA-lined valves are not always the optimal choice. Consider alternatives when:
Temperature Exceeds PFA Limits
For continuous service above +180°C:
• Ceramic-lined valves
• Exotic metal alloys (Hastelloy, titanium, tantalum)
• Specialized high-temperature polymers
Example: HPAL autoclaves at 225-250°C require titanium, not PFA.
Abrasive Slurry Service
Heavy solids loading accelerates wear on any polymer lining:
• Ceramic-lined valves for severe abrasion
• Rubber-lined valves for moderate slurry service
• Metal knife gate valves for heavy slurries
PFA handles light solids; severe abrasion requires harder materials.
Cost-Sensitive Standard Service
For common chemicals at moderate conditions, less expensive options exist:
• PTFE-lined valves – similar resistance, lower cost
• Polypropylene valves – suitable for dilute acids, ambient temperatures
• PVC/CPVC valves – limited temperature and pressure, low cost
PFA premium is justified by extended service life in demanding applications.
Non-Corrosive Service
Standard stainless steel or carbon steel valves are appropriate when:
• Media is not chemically aggressive
• Temperature and pressure are within metal valve ratings
• Purity requirements don't mandate polymer contact
Comparing Fluoropolymer Lining Options
GFT9 offers PFA and PVDF lining options. Understanding their differences helps select the optimal material for your application.
PFA (Perfluoroalkoxy) Lining
Maximum operating temperature: +180°C in GFT9 valves. Chemical resistance is excellent and universal—PFA handles virtually all industrial chemicals except molten alkali metals and elemental fluorine. Surface quality is excellent with smooth, non-porous finish. Purity level is the highest available, making PFA the standard for semiconductor and pharmaceutical applications. Cost is higher but justified by superior performance and extended service life.
PVDF (Polyvinylidene Fluoride) Lining
Maximum operating temperature: +120°C in valve applications. Chemical resistance is very good with some limitations—excellent for halogens (chlorine, bromine) but has limitations with strong bases, amines, and ketones. Surface quality is good and suitable for most industrial applications. Purity level is high and acceptable for many applications. Cost is lower than PFA, making it attractive for chlorine service within temperature limits.
Selection Guidance:
Choose PFA when your application requires temperatures above 120°C, involves mixed chemicals including bases, demands highest purity standards, or requires universal chemical compatibility without exception.
Choose PVDF when your application primarily involves chlorine or halogen service, operates consistently below 120°C, has cost constraints that preclude PFA, and doesn't require contact with strong bases or amines.
Quick Selection Criteria
Use this decision framework to evaluate PFA-lined valve suitability:
Step 1: Check Temperature
• Operating temperature continuously above +180°C? → Consider exotic metals or ceramics
• Operating temperature below +180°C? → PFA is suitable, continue evaluation
Step 2: Identify Chemical Environment
• Strong mineral acids, caustics, oxidizers? → PFA provides superior life
• Mixed chemicals or multipurpose service? → PFA universal resistance is advantageous
• Mild chemicals at low temperatures? → Less expensive options may suffice
Step 3: Evaluate Purity Requirements
• Semiconductor, pharmaceutical, ultrapure water? → PFA recommended
• Standard industrial service? → PTFE may be acceptable
Step 4: Consider Total Cost of Ownership
• Frequent replacement of stainless steel or other materials? → PFA reduces total cost
• Long equipment life required? → PFA provides extended service
• Budget-constrained, replaceable application? → Consider alternatives
Step 5: Check Special Requirements
• ATEX zone with flammable media? → Specify anti-static PFA (PFA-AS)
• Abrasive solids present? → Evaluate ceramic or rubber alternatives
• Vacuum service required? → Confirm vacuum rating
Industry-Specific Recommendations
Based on typical process conditions and requirements in each industry, we recommend the following materials. Each industry links to detailed application guidance.
Semiconductor Manufacturing
- Primary recommendation: PFA with stainless steel body (1.4408)
- Key considerations: Highest purity requirements, ultrapure chemicals, contamination prevention
- View Semiconductor Industry Page →
Pharmaceutical & API Production
- Primary recommendation: PFA with stainless steel body (1.4408)
- Key considerations: USP Class VI compliance, cleanability, documentation requirements
- View Pharmaceutical Industry Page →
Chemical Processing
- Primary recommendation: PFA with carbon steel body (1.0619)
- Alternative: PVDF for chlorine-only service below 120°C
- Key considerations: Universal chemical resistance, mixed acid/base service
- View Chemical Processing Page →
Mining & Hydrometallurgy
- Primary recommendation: PFA with carbon steel body (1.0619)
- Key considerations: Acid leaching circuits, solvent extraction, temperature limitations for HPAL
- View Mining Industry Page →
Pulp & Paper
- Primary recommendation: PFA with carbon steel body (1.0619)
- Key considerations: Chlorine dioxide service, documented 10+ year service life in bleach plants
- View Pulp & Paper Page →
Water & Wastewater Treatment
- Primary recommendation: PFA or PVDF depending on chemical service
- Key considerations: Sodium hypochlorite handling, chlorine dosing, ozone compatibility
- View Water Treatment Page →
Energy Sector (Hydrogen, Battery, Oil & Gas)
- Primary recommendation: PFA with material depending on application
- Key considerations: KOH electrolyte in electrolyzers, NMP in battery manufacturing, H₂S service
- View Energy Sector Page →
Need Help Selecting the Right Material?
Our engineering team provides application-specific recommendations based on your actual process conditions. Contact us with:
• Process chemicals and concentrations
• Operating temperature and pressure ranges
• Purity or regulatory requirements
• Any special conditions (ATEX, vacuum, abrasives)
Email: sales@gft9.shop
Phone: +49 2152 9154990
We'll recommend the appropriate material and provide supporting technical documentation.