Passivation Time & Temperature Calculator
Calculate required contact time and temperature for stainless steel passivation. Supports citric acid and nitric acid methods per ASTM A967, AMS 2700, and pharmaceutical requirements.
Calculate Passivation Parameters
Enter your specifications to determine required contact time, temperature range, and complete procedure
⚗️ Passivation Parameters
Disclaimer: This calculator is provided for informational purposes only. Always verify parameters with applicable specifications and perform validation testing.
Ready to Calculate
Enter your passivation parameters on the left and click "Calculate" to see required contact time, temperature range, and complete specifications.
Every 10°F increase roughly doubles the reaction rate. Optimize your parameters for faster cycles without compromising quality.
Citric vs. Nitric Acid Passivation
Compare the two primary passivation methods to choose the best approach for your application
- Environmentally friendly & biodegradable
- No NOx fumes or hazardous disposal
- Excellent for pharmaceutical applications
- Works well on all 300-series alloys
- Better rouge removal capability
- Lower equipment corrosion risk
- Traditional industry standard method
- Strongly oxidizing for thick oxide layer
- Required by some legacy specifications
- Effective scale and smut removal
- Lower chemical cost per gallon
- Faster brightening effect
Alloy Passivation Guide
Passivation difficulty and recommended parameters by alloy type
ASTM A967 Standard Parameters
Minimum requirements by method per ASTM A967 specification
| Method | Chemical | Concentration | Temperature | Time | Best For |
|---|---|---|---|---|---|
| Citric 3 | Citric Acid | 4-10% w/w | 70-160°F | 4-30 min | All 300 series, general use |
| Citric 7 | Citric + Additives | 4-10% w/w | 120-140°F | 10-30 min | Enhanced cleaning, rouge removal |
| Nitric 5 | Nitric Acid | 20-25% | 70-130°F | 20-30 min | 304, 304L, 321, free-machining |
| Nitric 6 | Nitric Acid | 20-25% | 120-130°F | 20-30 min | 316, 316L, 317L, high-Mo alloys |
| Nitric 7 | Nitric + Dichromate | 20% + 2-3% | 120-160°F | 20-30 min | 300 + 400 series, aggressive |
| Chelant | Proprietary | Per mfg | 100-140°F | 15-60 min | All grades, specialty applications |
Related Calculators & Resources
More tools to help with your passivation projects
Chemical Dilution Calculator
Calculate exact chemical volumes and concentrations for citric acid, nitric acid, and cleaning solutions.
Use Calculator →Piping Volume Calculator
Calculate pipe volumes, surface areas, and chemical requirements for system passivation.
Use Calculator →Flow Rate Calculator
Determine GPM requirements and Reynolds number for effective chemical circulation.
Use Calculator →ASTM A967 Guide
Complete reference for passivation methods, testing requirements, and acceptance criteria.
Read Guide →Frequently Asked Questions
How does temperature affect passivation time?
Temperature has an exponential effect on reaction rate. Every 10°F increase roughly doubles the rate, allowing shorter contact times. At 140°F, citric acid may need only 10-15 minutes vs. 25-30 minutes at 70°F. However, temperatures above 160°F can cause etching or decomposition.
What happens if contact time is too short?
Insufficient time results in incomplete chromium oxide formation, leaving free iron that will corrode. This leads to copper sulfate test failures, early corrosion, and potential product contamination. Always meet or exceed minimum times.
Why does 316L need different parameters than 304?
316L has higher nickel and molybdenum content, changing passivation kinetics. It typically requires higher temperatures (120-130°F minimum) for nitric acid. Citric acid works well at moderate temperatures. The higher alloy content makes 316L more forgiving.
Can I use higher concentration to reduce time?
Yes, within limits. Increasing citric from 6% to 10% can reduce time by 30-40%. However, above 10% provides no additional benefit. For nitric, above 25% causes excessive etching. It's often better to increase temperature slightly instead.
Do contaminated parts need longer time?
Yes. Parts with heavy rouge, weld scale, or iron contamination may need 2-3× normal time, or pre-cleaning before passivation. Some cases require an initial derouging step at 10-15% citric for 30-60 minutes before final passivation.
Which method is better for pharmaceutical applications?
Citric acid is strongly preferred for pharmaceutical and biotech. It's safer to handle, environmentally friendly, produces no hazardous fumes, and is easier to validate. Most pharma facilities have moved away from nitric acid entirely.
Need Professional Passivation Services?
CXP Solutions provides ASTM A967 and AMS 2700 compliant passivation with validated procedures, complete documentation, and nationwide service. We handle all aspects from pre-cleaning through final testing.