What is equipment hygienic design?

  • John Zabkowicz
  • November 9, 2016

Equipment design is a critical part of the hygienic design process.  Hygienic equipment design focuses on all items that have direct or indirect contact with the manufactured products. They include items such as:

  • Material selections
  • Surface finishes
  • Joints
  • Ability for inspection
  • Drainage
  • Radii

Material selection for equipment design should focus on both physical, mechanical and operations properties. These products should be inert, non-toxic, non-corrosive. They should also be durable, smooth and free from any cracks or crevices. Finally, these products must be easily cleaned and maintained to reduce processing costs.

Stainless steel alloys 304 & 316L offered by Sanitary Fittings provide an excellent hygienic choice for your processing needs.

Surface finishes are also critical for hygienic design.  Typical steel products, which may appear smooth to the naked eye and touch most likely contain microscopic rough edges and pockets.  In order to eliminate these imperfections abrasive grinding and sanding procedures are applied to the surface.  3A Standards call for a final surface to be less than 32 Ra.  Think of this rating in terms of sandpaper grits.  The smoother the sandpaper the less gauge that is denoted.  Through extensive testing and experimentation, 3A has discovered that at this level of surface finish the material on surfaces does not lend it nooks or pockets which may breed bacteria and other germs.

Permanent joints within the process lines can either be cleanable or non-cleanable.  Non-cleanable joints should not  come in contact with product during processing.  This type of design requires manual cleaning processes to take place after each production run to insure proper hygienic procedures are followed.  This cleaning process adds to manufacturing costs and should be avoided through proper hygienic design.

All process line surfaces need to be made available for inspection and cleaning.  Regardless of cleaning method such as clean-in-place (CIP) or clean-out-of-place (COP).  The only exception to accessibility is a continuous run including welds.  These lines are still open for inspection as it relates to product testing for quality.  The simple rule of “if you cannot see it, you cannot clean it” applies to this design feature.

Standards require that all systems shall be self draining to avoid pooling and collection of product material in lines.  The current recommendation is 1/8″ per foot of run.

It’s nearly impossible to have a product line that does not contain bends or corners.   However, these bends in process lines open the potential for pooling or collection of products.  Sharp bends are harder to clean and are more susceptible to contamination versus large sweeping bends.  A 1/4″ radius is recommended for all bends.  However, certain industries like food and beverage typically go with a 1″ – 2″ radius for easier cleaning capabilities.