Nitric Acid (68%) vs Stainless Steel Compatibility
Verified chemical resistance rating (Safe for Continuous Industrial Service), thermal boundary limits (Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service), and material specification guide for Stainless Steel exposed to Nitric Acid (68%) in Strong Oxidizing / Mineral Acid service.
Nitric Acid (68%) vs Stainless Steel: A1-Excellent
Exposing Stainless Steel to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2) carries an official rating of A1-Excellent (Safe for Continuous Industrial Service). Maximum recommended thermal operating limit: Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service. Best Grade A alternative materials for continuous or high-temperature service: 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 | Stainless Steel |
| Official Resistance Rating | A1-Excellent (Grade A) |
| Engineering Service Verdict | Safe for Continuous Industrial Service |
| Max Temp and Concentration Limit | Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service |
| Best Grade A Alternatives | 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 Stainless Steel: A1 – Excellent (No Effect up to 120°F / 49°C)
Summary Verdict: 316 / 304 Austenitic Stainless Steel is rated A1-Excellent (Safe for Continuous Industrial Service) when exposed to Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). Approved for primary wetted components including continuous-duty piping, bulk storage tanks, pump manifolds, and static/dynamic seals.
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 | 316 / 304 Austenitic Stainless Steel (Passivated Chromium-Nickel-Molybdenum Alloy) |
| Official Resistance Rating | A1 – Excellent (No Effect up to 120°F / 49°C) (Grade A) |
| Recommended Temperature Window | Up to 120°F (49°C) verified; up to material thermal limit in non-pressurized service (Material limit: -325°F to 800°F (-198°C to 426°C)) |
| Top Grade-A Alternatives | 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 Stainless Steel, engineers must account for both concentration-dependent chemical attack and thermal stress:
- Reaction & Failure Mechanism: Exhibits negligible weight change, zero surface crazing, and minimal dimensional swelling (<1%) across extended immersion testing.
- Material Profile (Stainless Steel): Superior mechanical strength, high-temperature tolerance, and complete immunity to organic solvent swelling in ketones, esters, aromatics, and fuels. However, vulnerable to catastrophic localized pitting, crevice corrosion, and chloride stress-corrosion cracking (SCC) in halide acids (HCl, HBr), ferric/cupric chlorides, and sodium hypochlorite bleach.
- Application Scope: Common wetted components include high-pressure process piping, sanitary food/pharma vessels, centrifugal pump casings, heat exchangers, and valve bodies.
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 Stainless Steel 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 (Current Page) | 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 Stainless Steel compatible with Nitric Acid (68%)?
Stainless Steel is rated A1-Excellent (Safe for Continuous Industrial Service) with Nitric Acid (68%) (Formula: HNO3 (68% Azeotropic Concentrated), CAS: 7697-37-2). Exhibits negligible weight change, zero surface crazing, and minimal dimensional swelling (<1%) across extended immersion testing. Approved for primary wetted components including continuous-duty piping, bulk storage tanks, pump manifolds, and static/dynamic seals.
What is the best alternative material for handling Nitric Acid (68%)?
If Stainless Steel does not meet your temperature or pressure requirements for Nitric Acid (68%), the highest-rated Grade A alternatives are Viton, PTFE, PVDF. Always verify O-ring elastomers and metallic fasteners separately before full-scale deployment.
Technical Engineering FAQs: Nitric Acid (68%) vs Stainless Steel
Click any question below for chemical failure-mode specifics, thermal derating limits, and material selection rules: