USP Class VI Sanitary Gaskets……What is Available?

January 20, 2014
Platinum Cured Silicone Gaskets Normally do pass USP Class VI Criteria. White Silicone Gaskets do not.

Platinum Cured Silicone Gaskets Normally do pass USP Class VI Criteria. White Silicone Gaskets do not.

We sell tens of thousands of sanitary Tri-Clamp gaskets every year for food, beverage, and personal care and biopharmaceutical applications.  For most food, beverage and personal care applications, sanitary gaskets that are made from FDA CFR Title 21 approved materials are sufficient.  But the biopharmaceutical industry normally requires sanitary gaskets that not only require the material to meet FDA standards but also have passed USP Class VI testing criteria.  We have detailed the USP Class VI requirements in posts previously and will not go into the criteria here. In this post we wanted to explain what sanitary gaskets are easily commercially available with FDA approval and which also have USP Class VI approvals.

FDA CFR Title 21 Approved Only Sanitary Clamp Gaskets

  • Buna Rubber:   These are the least expensive of all sanitary gaskets.  You can get both black and white Buna Gaskets.  Used throughout the dairy industry, they are easily available in sizes ½”-12”
  • EPDM:  Sulfur cured EPDM are also inexpensive and available in a broad size offering.  EPDM has broader chemical resistant and thermal properties than Buna, but is not resistant to fats and oils.
  • White Silicone: To our knowledge these are FDA approved only.  They are readily available ½”-4”

USP Class VI Tested Sanitary Clamp Gaskets

  • Platinum Cured Silicone:  These are available in different durometers.  You also have a choice of gaskets manufactured from LIM material (liquid injected molded) or sheets of silicone resins.  We will address our opinion of the difference in gaskets made from these two processes in a future post.  Platinum cured silicone Tri-Clamp gaskets are readily available in sizes ½”-12”.
  • Teflon (PTFE):  Most Teflon gaskets on the market today have USP Class VI certification.  While Teflon gaskets can present some challenges from a sealing standpoint, they are very invert and resistant to high temperatures. Teflon sanitary gaskets are commercially available in sizes ½”-6”.
  • EPDM:  Peroxide cured EPDM gaskets are available in sizes ½”-12”.  EPDM is used in a lot of biopharmaceutical application where intermittent steam sterilization occurs.  EPDM does not hold up well with fats and oils.
  • Viton (FKM):  Most Viton sanitary gaskets on the market today have passed USP Class VI testing requirements.  Viton can be an excellent choice in high temperature applications and generally has higher chemical resistance than most elastomers.  Sanitary FKM gaskets are commercially available in sizes ½”-12”.
  • Envelope gaskets:   There are envelope gaskets on the market consisting of an outer layer of Teflon with and inner core of either EPDM or Viton.  This gives the gasket the chemical resistance of Teflon will providing more resiliency and better sealing properties that a standard Teflon gasket. These are available in sizes ½”-12”.
  • PTFE/316 Stainless Blend Gaskets:  This is an interesting material made from molds Teflon resins with sintered stainless steel particle.  They have excellent chemical and thermal resistance and meet USP Class VI standards.  They are available ½”-12”
  • Designer materials- perfluoroelstamoers, like Kalrez, offer chemical compatibility and resistance similar to Teflon while provider the elasticity and sealing capabilities of traditional elastomers. Other “designer” products, such as Viton GF and ETP are available and will be the focus of future product posts.

So that was a quick overview of what sanitary gaskets are readily available with USP Class VI certification in today market.  If you are not sure what material is best for your application, contact us and we will walk through your application with you and give our recommendation.  Our people are well schooled in determining the most cost effective material that will meet all of your application criteria.  Remember when you are going through your requirements to include all of process requirements, i.e.  not just the characteristics product you are pumping, but the cleaning criteria as well.