Nitric Acid (68%) vs PTFE Compatibility
Verified chemical resistance rating (Safe for Continuous Industrial Service), thermal boundary limits (Ambient to elevated operating temperatures within standard material limits), and material specification guide for PTFE exposed to Nitric Acid (68%) in Strong Oxidizing / Mineral Acid service.
Nitric Acid (68%) vs PTFE: A-Excellent
Exposing PTFE to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2) carries an official rating of A-Excellent (Safe for Continuous Industrial Service). Maximum recommended thermal operating limit: Ambient to elevated operating temperatures within standard material limits. Best Grade A alternative materials for continuous or high-temperature service: Stainless Steel, Viton, PVDF.
Technical Specifications and Operating Parameters
| Chemical Medium | Nitric Acid (68%) |
|---|---|
| Chemical Formula | HNO3 (68% Azeotropic Concentrated) |
| CAS Registry Number | 7697-37-2 |
| Chemical Functional Class | Strong Oxidizing / Mineral Acid |
| Wetted Material | PTFE |
| Official Resistance Rating | A-Excellent (Grade A) |
| Engineering Service Verdict | Safe for Continuous Industrial Service |
| Max Temp and Concentration Limit | Ambient to elevated operating temperatures within standard material limits |
| Best Grade A Alternatives | Stainless Steel, Viton, PVDF |
| Backtest and Audit Verification | Verified against Cole-Parmer, ISM, Graco & CP Lab Safety industrial chemical resistance charts. |
Nitric Acid (68%) Cross-Material Comparison Matrix (9 Materials)
Direct benchmark ratings across all 9 reference industrial materials for Nitric Acid (68%):
| Material Name | Compatibility Rating | Service Verdict | Temperature Limit | Datasheet |
|---|---|---|---|---|
| Buna-N | D-Severe Effect | Incompatible — Immediate Failure Risk | Not recommended at any temperature or concentration | Report |
| EPDM | D-Severe Effect | Incompatible — Immediate Failure Risk | Not recommended at any temperature or concentration | Report |
| HDPE | D-Severe Effect | Incompatible — Immediate Failure Risk | Not recommended at any temperature or concentration | Report |
| Polypropylene | D-Severe Effect | Incompatible — Immediate Failure Risk | Not recommended at any temperature or concentration | Report |
| PTFE | A-Excellent | Safe for Continuous Industrial Service | Ambient to elevated operating temperatures within standard material limits | Report |
| PVC | C1-Fair | Caution: Short-Term or Emergency Use Only | Short-term exposure only; avoid continuous pressurized service | Report |
| PVDF | A1-Excellent | Safe for Continuous Industrial Service | Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service | Report |
| Stainless Steel | A1-Excellent | Safe for Continuous Industrial Service | Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service | Report |
| Viton | A1-Excellent | Safe for Continuous Industrial Service | Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service | Report |
Chemical and Material Interaction Analysis
Engineering Compatibility Verdict
Nitric Acid (68%) vs PTFE: A – Excellent (Fully Compatible)
Summary Verdict: PTFE (Teflon® / Polytetrafluoroethylene) is rated A-Excellent (Safe for Continuous Industrial Service) when exposed to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). Approved for continuous fluid handling, bulk storage, valves, and sealing assemblies.
Quick Engineering Specifications
| Chemical Media | Nitric Acid (68%) |
|---|---|
| Chemical Formula | HNO3 (68% Azeotropic Concentrated) |
| CAS Registry Number | 7697-37-2 |
| Chemical Classification | Strong Oxidizing / Mineral Acid |
| Wetted Material | PTFE (Teflon® / Polytetrafluoroethylene) (Fully Fluorinated Perfluoropolymer) |
| Official Resistance Rating | A – Excellent (Fully Compatible) (Grade A) |
| Recommended Temperature Window | Ambient to elevated operating temperatures within standard material limits (Material limit: -328°F to 500°F (-200°C to 260°C)) |
| Top Grade-A Alternatives | Stainless Steel, Viton, PVDF |
| Data Verification Status | Verified against Cole-Parmer, ISM, Graco & CP Lab Safety industrial chemical resistance charts. |
Chemical & Material Interaction Analysis
Nitric Acid (68%) is classified as a strong oxidizing / mineral acid (corrosive proton attack combined with strong oxidative potential). Used in chemical synthesis, metal pickling, pH neutralization, and industrial etching. When selecting wetted components for PTFE, engineers must account for both concentration-dependent chemical attack and thermal stress:
- Reaction & Failure Mechanism: Chemically inert interface with no measurable corrosion, polymer chain scission, or elastomeric swell under standard operating conditions.
- Material Profile (PTFE): Near-universal chemical inertness across strong mineral acids, concentrated caustics, ketones, esters, chlorinated solvents, and amines up to 500°F. However, susceptible to cold flow (creep) under high mechanical load and reactive only with elemental fluorine gas, chlorine trifluoride, or molten alkali metals.
- Application Scope: Common wetted components include lined chemical transfer piping, diaphragm pump elastomers, ball valve seats, expansion joints, and high-purity semiconductor fluid handling.
Cross-Material Compatibility Comparison for Nitric Acid (68%)
To help you select the longest-lasting piping, valve lining, or O-ring seal for Nitric Acid (68%), the table below compares PTFE against 8 other common industrial engineering materials:
| Wetted Material | Compatibility Rating | Service Recommendation | Material Temp Range |
|---|---|---|---|
| Polypropylene (PP Homopolymer & Copolymer) | D-Severe Effect | Incompatible — Immediate Failure Risk | 32°F to 180°F (0°C to 82°C) |
| 316 / 304 Austenitic Stainless Steel | A1-Excellent | Safe for Continuous Industrial Service | -325°F to 800°F (-198°C to 426°C) |
| Viton® (FKM Fluoroelastomer) | A1-Excellent | Safe for Continuous Industrial Service | -15°F to 400°F (-26°C to 204°C) |
| PTFE (Teflon® / Polytetrafluoroethylene) (Current Page) | A-Excellent | Safe for Continuous Industrial Service | -328°F to 500°F (-200°C to 260°C) |
| EPDM (Ethylene Propylene Diene Monomer) | D-Severe Effect | Incompatible — Immediate Failure Risk | -60°F to 300°F (-51°C to 149°C) |
| PVC Type I (Unplasticized Polyvinyl Chloride / uPVC) | C1-Fair | Caution: Short-Term or Emergency Use Only | 32°F to 140°F (0°C to 60°C) |
| PVDF (Kynar® / Polyvinylidene Fluoride) | A1-Excellent | Safe for Continuous Industrial Service | -40°F to 280°F (-40°C to 138°C) |
| Buna-N (Nitrile / NBR Elastomer) | D-Severe Effect | Incompatible — Immediate Failure Risk | -40°F to 250°F (-40°C to 121°C) |
| HDPE (High-Density Polyethylene) | D-Severe Effect | Incompatible — Immediate Failure Risk | -60°F to 140°F (-51°C to 60°C) |
Frequently Asked Questions (FAQ)
Is PTFE compatible with Nitric Acid (68%)?
PTFE is rated A-Excellent (Safe for Continuous Industrial Service) with Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). Chemically inert interface with no measurable corrosion, polymer chain scission, or elastomeric swell under standard operating conditions. Approved for continuous fluid handling, bulk storage, valves, and sealing assemblies.
What is the best alternative material for handling Nitric Acid (68%)?
If PTFE does not meet your temperature or pressure requirements for Nitric Acid (68%), the highest-rated Grade A alternatives are Stainless Steel, Viton, PVDF. Always verify O-ring elastomers and metallic fasteners separately before full-scale deployment.
Technical Engineering FAQs: Nitric Acid (68%) vs PTFE
Click any question below for chemical failure-mode specifics, thermal derating limits, and material selection rules: