US FDA
21 CFR 211.65 - Equipment Construction - Contact Surfaces
Plain-language explanation, inspection context and common violation patterns.
What it says
Equipment surfaces that contact components, in-process materials or drug products must not be reactive, additive or absorptive so as to alter the safety, identity, strength, quality or purity of the product beyond official or established requirements.
Paraphrased for plain-language clarity. Always verify against the current published regulation text.
What it means in practice
- This provision covers the material science of equipment, not just its overall design - the specific alloys, coatings, gaskets and seals that actually touch product matter individually.
- A surface that was appropriate for one product or process can become inappropriate when the product formulation, cleaning agent, or process condition changes, requiring reassessment.
- Absorptive surfaces are a particular risk for potent or low-dose products, where even small amounts of product retained in a surface can create carryover or cross-contamination risk.
What FDA inspectors look for
- Documented material compatibility assessment for all product-contact surfaces, not just an assumption based on the equipment being generically pharmaceutical-grade.
- Whether surface condition is monitored over time for degradation, pitting or coating breakdown that could change its reactivity or absorptive properties.
- Whether cleaning validation data accounts for the specific contact surface materials actually in use.
Most common violation
Equipment surfaces assumed to be compatible based on general pharmaceutical use without product-specific or process-specific material compatibility documentation, particularly after a formulation or cleaning agent change.
Want a deeper, interactive breakdown?
GMPify's Regulation Explainer tool gives subscribers an AI-powered analysis of any 21 CFR, EU GMP, USP or ICH reference, with live inspection context.
Try the Regulation Explainer →