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SS316 for product contact

SS316 for product contact

SS316 for product contact

Does anyone know what the acceptable limits are for surface finish on Stainless steel 316 that is used to carry sterile products? Suppliers of SS suggest a Ra 5-9 but what is the FDA standard?

RE: SS316 for product contact

The FDA does not give specific standards like this for piping.  If you use Ra10 or less for tubing 4" and less and Ra20 for greater than 4", you will be fine.

RE: SS316 for product contact

For sterile products you have standards for 316SS for type of products (food, Farma)and thsy specify the polish or preparation of the wetted surfaces required, and also the reduction of dead spaces created in the product.

RE: SS316 for product contact

ISPE will issue later this year a
Biopharmaceuticals Baseline® Guide

More info at

I have seen the draft, which states on page 47:

"The finish of surfaces that contact product or related media shall support the cleaning regimen required to maintain consistent processing and maintain product specifications.

There are no maximum or minimum degrees of surface finish. However the surface finish used shall be able to be consistently measurable as specified.

As a guideline, the above criteria typically translates into 316L stainless steel or alloys being mechanically polished to 25 micro-inch Ra, as the roughest finish that supports cleaning qualification.

For process steps that are prone to fouling (such as fermentation) a higher level of surface finish may be advisable to facilitate cleaning."

Electropolish is not required, but can be considered to further improve cleanability and corrosion resistance.
<end quote>

for the record : 25 micro-inch = 0.625 mu meter

I suppose basically this means that by following the above guideline, no problems should be expected with the FDA, whereas if exceeding the limit, it may also be accepted, provided one can give a good reason.

Hope this helps


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