In pharmaceutical manufacturing, food processing, and healthcare facilities, ordinary plant steam is not good enough. Equipment sterilisation, humidification in cleanrooms, and direct contact applications require clean steam — steam that meets stringent purity standards to ensure product safety, sterility, and regulatory compliance.

What Is Clean Steam?

Clean steam (also called pure steam) is steam generated from high-purity feedwater (typically purified water or WFI — Water for Injection) using a dedicated clean steam generator. Unlike plant steam which may contain:

• Chemical treatment additives (amines, oxygen scavengers, phosphates)
• Scale inhibitors and corrosion inhibitors
• Dissolved solids from hard water
• Pipe scale and corrosion products

Clean steam condensate meets the quality requirements of purified water or WFI, making it safe for direct product contact and sterile surface contact.

When Is Clean Steam Required?

• Autoclave / steriliser sterilisation (EN 285, ISO 17665) — steam contacts the product load and vessel interior
• Clean-in-Place (CIP) and Steam-in-Place (SIP) — direct steam injection for pipeline sterilisation
• Vial and ampoule washing machines — steam contacts sterile primary packaging
• Cleanroom HVAC humidification — steam injected directly into classified air
• Food contact applications — direct steam injection into food products (e.g., UHT processing, steam peeling)
• Surgical instrument sterilisation in hospitals (HTM 01-01, AS/NZS 4187)

Relevant Standards for Clean Steam

Clean Steam Generator Design

A clean steam generator (CSG) is essentially a heat exchanger — plant steam heats the shell side, while purified water on the tube side is converted to clean steam. The two streams never mix, so no plant steam contaminants enter the clean steam.

Key design features:

• 316L stainless steel construction — all parts in contact with clean steam and condensate
• Electropolished internal surfaces — Ra ≤ 0.5 µm for cleanability and reduced biofilm risk
• Purified water or WFI feedwater — generated by RO + EDI or distillation
• Continuous blowdown — to remove concentrated dissolved solids from the evaporator
• ASME BPE or EN 13480 construction — with full material and weld documentation

Clean Steam Distribution System

The distribution system must maintain steam quality from generator to point of use:

• 316L SS orbital welded pipework with full weld map documentation
• Sanitary steam traps — designed for CIP/SIP, with no crevices or dead legs
• Slope to drain — minimum 1:100 slope to prevent condensate accumulation and bacterial growth risk
• Insulated pipework — to maintain steam quality and prevent condensation
• No dead legs — maximum 6D rule (dead leg length ≤ 6× pipe diameter)

Steam Quality Testing

EN 285 and pharmacopoeia standards require periodic testing of clean steam quality. Tests include:

• Dryness fraction — measured by calorimeter test; should be ≥ 0.95
• Superheat — temperature above saturation; should be ≤ 25K
• Non-condensable gases — measured by gas trap method; should be ≤ 3.5% by volume
• Condensate conductivity — ≤ 4.3 µS/cm at 20°C
• Endotoxins — ≤ 0.25 EU/mL for WFI-grade steam condensate

Clean Steam Equipment from PureSys India

PureSys India supplies clean steam generators, sanitary steam traps, and pharmaceutical grade steam equipment for the pharma, biotech, food, and healthcare sectors in India. We work with leading manufacturers and can support validation documentation (IQ/OQ/PQ protocols).

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