Surface Roughness in Pure Steam Systems — GMP Rule or Industry Best Practice?

In pharmaceutical manufacturing, pure steam plays a vital role in sterile and aseptic operations, particularly for sterilizing equipment, containers, and pipelines. A common debate centers on whether the internal surface roughness (Ra) of pipes—often specified as Ra < 0.8 µm—is a GMP requirement or simply an industry design standard.

Regulatory guidelines, such as EU GMP Part 1 (Sections 3.38–3.39), emphasize that equipment must prevent contamination and not adversely affect product quality. However, neither EU GMP nor FDA regulations define specific surface roughness criteria for pure steam systems. Instead, they focus on cleanability, suitability, and contamination prevention.

The Ra < 0.8 µm specification is thus not a direct GMP mandate but rather an industry best practice, adapted from WFI and PW system standards. Electropolishing may delay rouging but could cause particle flaking, making its use debatable.

Since rouge particles cannot be fully avoided, point-of-use filters (0.1–10 µm) are recommended to capture residues and stabilize pressure.

Conclusion: While not a regulatory requirement, maintaining Ra ≤ 0.8 µm demonstrates adherence to current best practices, ensuring both process integrity and product protection.

02-11-2025