Published on 07/12/2025
Pure Steam & Clean Steam Validation: Quality, Sampling & Testing Guidelines
Steam is a critical utility in pharmaceutical manufacturing, especially for sterilization, SIP (Sterilization-in-Place), and cleaning. When steam directly contacts product surfaces or sterile equipment, it must meet stringent purity and quality standards. This is where pure steam and clean steam validation becomes essential to ensure compliance with global GMP and pharmacopoeial standards.
This article provides an end-to-end tutorial on how to validate pure steam and clean steam systems in pharma, including qualification stages (DQ, IQ, OQ, PQ), steam sampling methods, and essential quality tests.
Definitions: Pure Steam vs Clean Steam
- Clean Steam: Steam generated using clean feed water (typically purified water) and used for indirect contact or equipment sanitization.
- Pure Steam: Steam derived from Water for Injection (WFI), used in direct contact with sterile components or product-contact surfaces. It must condense to WFI standards.
Regulatory Expectations and Guidelines
- EU GMP Annex 1
- FDA Guidance on Process Validation
- ICH Q9 – Risk Management
- WHO TRS 970 Annex 2
- EN 285 – Sterilization Standard for Steam Sterilizers
System Qualification Approach (DQ → IQ → OQ → PQ)
Design Qualification (DQ)
- Define feedwater source (WFI or Purified Water)
- Specify
Installation Qualification (IQ)
- Verify installation of pressure gauges, temperature sensors, and safety valves
- Confirm steam generator calibration and system integration
- Weld documentation and passivation records
- Insulation verification and sample valve tagging
- Review of manufacturer documents and utility supply connections
Operational Qualification (OQ)
- Check alarm functions (low feed pressure, high pressure cutoff)
- Conduct empty chamber runs in sterilizers to assess uniformity
- Temperature mapping of distribution headers
- Steam pressure and flow testing under various load conditions
- Condensate drain response test at lowest point
Performance Qualification (PQ) – Steam Quality Tests
Steam must meet the following 3 critical parameters based on EN 285 and USP standards:
1. Non-Condensable Gases (NCG) Test
- Measure gases like air, nitrogen in steam via collection in a submerged container
- Acceptance limit: ≤ 3.5% v/v of total condensate
- High NCG can prevent proper sterilization by insulating microbes
2. Dryness Fraction (Steam Dryness)
- Indicates the moisture content of steam. Value should be ≥ 0.95
- Wet steam can cause ineffective sterilization and corrosion
3. Superheat Test
- Ensures steam is saturated and not superheated beyond sterilization threshold
- Acceptance: Saturated steam ≤ 25°C above boiling point at measured pressure
- Superheated steam may not condense, impairing heat transfer
Additional Quality Tests
| Parameter | Test Method | Acceptance Criteria |
|---|---|---|
| pH | USP | 5.0 – 7.0 |
| Conductivity | USP | WFI limits |
| Total Organic Carbon (TOC) | USP | ≤ 500 ppb |
| Endotoxins | USP | ≤ 0.25 EU/mL |
| Microbial Count | USP | ≤ 10 CFU/100 mL |
Sampling Methods
- Use cooled sampling devices with sterile condensate collection tubes
- Collect samples post 5-minute purge to remove condensate
- Ensure sterilized sample ports and aseptic technique
- Samples analyzed within validated hold times (e.g., TOC ≤ 2 hours)
Validation Report Contents
- DQ/IQ/OQ/PQ reports with raw data
- Steam quality test results and acceptance criteria
- Sample locations and rationale
- Deviation reports and CAPA (if any)
- Sterilizer validation linkage if steam used for autoclaves/SIP
Common Deviation Examples
- NCG > 3.5% → Check for vacuum leaks or poor degassing
- Dryness fraction < 0.95 → Revalidate traps or adjust generator controls
- TOC spike in condensate → Possible organic contamination in feed water
Routine Monitoring and Revalidation
- Annual requalification recommended
- Routine monitoring: condensate TOC, conductivity, and microbial tests
- Review alarm logs and event trends monthly
Conclusion
Pure steam and clean steam systems are critical for sterilization and hygienic operations in the pharmaceutical industry. Their validation must confirm consistent steam quality through physical tests like dryness, NCG, superheat, and chemical/microbial analyses. Incorporating robust qualification protocols and regular monitoring ensures sterility assurance and GMP compliance.
Download validation SOPs, steam test templates, and qualification protocols at PharmaSOP.in. For expert guidance on full utility system qualification, visit PharmaValidation.in.