What material should a diaphragm valve for Nitric Acid (HNO₃) be?

SS 304L (Excellent): Standard for all concentrations of HNO₃. More resistant than 316L due to lower Mo content. SS 316L (Good): Slightly lower corrosion resistance than 304L for HNO₃ due to molybdenum - but still widely used. Aluminium alloys (Good): Good for dilute HNO₃ - used in food-grade applications. PTFE (Good): Acceptable for dilute and concentrated HNO₃ at ambient temperature. Verify for fuming acid.

Nitric Acid (HNO₃) service

Service Selection

Diaphragm Valves for Nitric Acid (HNO₃) Service

Which diaphragm valves configuration suits Nitric Acid (HNO₃) (HNO₃), in which material, to which standard — from real service data, with the pitfalls flagged.

Which diaphragm valves for Nitric Acid (HNO₃)?

SS 304L diaphragm valve - Pharmaceutical or food-grade dilute HNO₃ - no dead-legs Typical service window: 1–20 bar, Ambient to 80°C.

Recommended Configurations

SS 304L diaphragm valve

Pharmaceutical or food-grade dilute HNO₃ - no dead-legs

Body Material for Nitric Acid (HNO₃)

Rated from real compatibility data - click any material for the full decision page.

SS 304LStandard for all concentrations of HNO₃. More resistant than 316L due to lower Mo content.Excellent SS 316LSlightly lower corrosion resistance than 304L for HNO₃ due to molybdenum - but still widely used.Good Aluminium alloysGood for dilute HNO₃ - used in food-grade applications.Good PTFEAcceptable for dilute and concentrated HNO₃ at ambient temperature. Verify for fuming acid.Good Carbon SteelOnly for >65% concentration at ambient temperature - passivation layer forms.Fair Hastelloy C-276Not ideal for HNO₃ - SS 304L is preferred due to Mo susceptibility.Fair Rubber (natural/NBR)Nitric acid attacks most rubbers and organics rapidly.Not Recommended

Governing Standards for Nitric Acid (HNO₃) Service

ASME B16.34 EN 1092 ISO 15848 (for toxic concentrated service)

What to Avoid in Nitric Acid (HNO₃) Service

Rubber-lined valves (nitric acid attacks all common rubbers)
Hastelloy C-276 for hot concentrated HNO₃ (Mo susceptibility)
Carbon steel for dilute HNO₃

Service Considerations

Fuming nitric acid (>85%) - extreme oxidiser, full PPE and emergency protocols required
All-welded construction preferred - no threaded joints in concentrated HNO₃
Stagnant acid in dead-legs causes localised attack - full-bore valves only
ATEX rating required where NOₓ fumes are present

Other valve types for Nitric Acid (HNO₃)

Ball Valves for Nitric Acid (HNO₃)Butterfly Valves for Nitric Acid (HNO₃)

Diaphragm Valves for other services

Diaphragm Valves for Sulphuric Acid (H₂SO₄)Diaphragm Valves for Hydrochloric Acid (HCl)Diaphragm Valves for Phosphoric Acid (H₃PO₄)Diaphragm Valves for Slurry - Abrasive Pulp / Mineral Slurry Diaphragm Valves for Demineralised Water (DM Water / Deionised Water)Diaphragm Valves for Ethanol / Industrial Alcohol (C₂H₅OH)Diaphragm Valves for Urea Solution (Carbamide / DEF / AdBlue)Diaphragm Valves for Acetic Acid (CH₃COOH)

Reviewed by Process Engineering, Vajra Industrial SolutionsDiscipline: Process & Fluid Service EngineeringLast reviewed: 20 June 2026

Connected Engineering

Standards

ASME B16.34

Products

Diaphragm Valves

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Relevant Products

Vajra Diaphragm Valves

Engineering references

Nitric Acid (HNO₃) service guideFull compatibility, standards & considerations Vajra Diaphragm ValvesFull range, specs & standards Spec Check engineValidate this spec before the RFQ