Nitric Acid (68%) vs Polypropylene Compatibility
Verified chemical resistance rating (Incompatible — Immediate Failure Risk), thermal boundary limits (Not recommended at any temperature or concentration), and material specification guide for Polypropylene exposed to Nitric Acid (68%) in Strong Oxidizing / Mineral Acid service.
Nitric Acid (68%) vs Polypropylene: D-Severe Effect
Exposing Polypropylene to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2) carries an official rating of D-Severe Effect (Incompatible — Immediate Failure Risk). Maximum recommended thermal operating limit: Not recommended at any temperature or concentration. Best Grade A alternative materials for continuous or high-temperature service: Stainless Steel, Viton, PTFE, 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 | Polypropylene |
| Official Resistance Rating | D-Severe Effect (Grade D) |
| Engineering Service Verdict | Incompatible — Immediate Failure Risk |
| Max Temp and Concentration Limit | Not recommended at any temperature or concentration |
| Best Grade A Alternatives | Stainless Steel, Viton, PTFE, 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 Polypropylene: D – Severe Effect (Do Not Use)
Summary Verdict: Polypropylene (PP Homopolymer & Copolymer) is rated D-Severe Effect (Incompatible — Immediate Failure Risk) when exposed to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). PROHIBITED for wetted service. Immediately substitute with an A-rated material shown in the cross-material comparison table below.
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 | Polypropylene (PP Homopolymer & Copolymer) (Semi-Crystalline Polyolefin Thermoplastic) |
| Official Resistance Rating | D – Severe Effect (Do Not Use) (Grade D) |
| Recommended Temperature Window | Not recommended at any temperature or concentration (Material limit: 32°F to 180°F (0°C to 82°C)) |
| Top Grade-A Alternatives | Stainless Steel, Viton, PTFE, 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 Polypropylene, engineers must account for both concentration-dependent chemical attack and thermal stress:
- Reaction & Failure Mechanism: Causes rapid, catastrophic material failure—including severe dissolution, stress cracking, extreme volumetric blowout (>25% swell), or rapid pitting corrosion (>50 mpy).
- Material Profile (Polypropylene): Broad resistance to aqueous acids, caustics, plating baths, and inorganic salt solutions without stress-corrosion cracking. However, susceptible to oxidative chain scission in strong oxidizing acids (fuming nitric/oleum) and rapid swelling/softening in chlorinated or aromatic hydrocarbons.
- Application Scope: Common wetted components include bulk chemical storage tanks, AODD pump manifolds, Schedule 80 piping, filter housings, and laboratory labware.
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 Polypropylene against 8 other common industrial engineering materials:
| Wetted Material | Compatibility Rating | Service Recommendation | Material Temp Range |
|---|---|---|---|
| Polypropylene (PP Homopolymer & Copolymer) (Current Page) | 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) | 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 Polypropylene compatible with Nitric Acid (68%)?
Polypropylene is rated D-Severe Effect (Incompatible — Immediate Failure Risk) with Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). Causes rapid, catastrophic material failure—including severe dissolution, stress cracking, extreme volumetric blowout (>25% swell), or rapid pitting corrosion (>50 mpy). PROHIBITED for wetted service. Immediately substitute with an A-rated material shown in the cross-material comparison table below.
What is the best alternative material for handling Nitric Acid (68%)?
If Polypropylene does not meet your temperature or pressure requirements for Nitric Acid (68%), the highest-rated Grade A alternatives are Stainless Steel, Viton, PTFE, PVDF. Always verify O-ring elastomers and metallic fasteners separately before full-scale deployment.
Technical Engineering FAQs: Nitric Acid (68%) vs Polypropylene
Click any question below for chemical failure-mode specifics, thermal derating limits, and material selection rules: