Sanitary gasket sealing solutions for UV, SIP and CIP sterilisation processes

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The food and beverage industries are under increased pressure by customers demanding a reduction in chemical additives and preservatives, resulting in an increased risk of bioburden on sanitary equipment.

Common sterilisation methods used by food and beverage producers include steam-in-place (SIP) and clean-in-place (CIP). However, an increasingly regulated and safety-conscious market has seen ever more stringent quality standards, resulting in producers turning to new methods.  Behind the scenes lies an innovative technology that is leading-the-way in efficient equipment sterilisation at an industrial scale. 

Ultraviolet germicidal irradiation (UVGI) is a method already accepted in food and beverage industries, yet recently gaining in popularity, as it offers a cost effective alternative to short-term process lines.  Highly effective at permanently eliminating the DNA of microorganisms, UVGI is low maintenance and environmental friendly.  With no toxins or residues released into the manufacturing process it does not affect the chemical composition, taste, odor or pH of the product.

UV-C lamps deliver precise medium-pressure ultra violet short-wavelengths of 254nm that travel through sanitary pipework, coming into contact with sanitary fittings such as tri-clamp connectors.  When it comes to the elastomer gaskets in tri-clamps connectors, understanding the application parameters of UV-sterilisation is important to ensuring seal longevity. 

Another dominant factor moving into UV-C technology is UV degradation of elastomer components. The UV interacts with the carbon bonds in the molecular chains of the elastomer. This produces free radicals which then react with oxygen to produce carbonyl groups, in other words a stress-induced chemical attack.

UV damaged o-ring sealThe earliest sign on exposed surfaces of elastomer gaskets will be discolouration, with excessive exposure in prone materials leading to subsequent cracking and, in extreme cases, disintegration.  To combat this, chemical UV stabilisers can be introduced into the formulation and carbon black is generally recognised as one of the most effective UV protection systems for use with elastomers.

For UV-sterilisation applications Precision Polymer Engineering offer a wide range of standard and custom elastomer gaskets, ranging from EDPM, VMQ, NBR, HNBR, FKM and FFKM material grades. As every sealing application is unique, PPE advise producers to contact our team with specific application requirements, in order to provide relevant technical guidance in selecting the right elastomer gasket.

On the other hand if UV is not the preferred method, SIP and CIP methods will still require a high performance elastomer material, as these cleaning regimes can shorten seal life if the elastomer is not compatible.

SIP stands for Steam-In-Place. The process uses thermal energy of condensing steam to sterilise, eliminating 99.9% of bioburden. Typical SIP cycle temperature parameters are 120°C to 135°C, at corresponding saturated steam pressure, with exposure time dependent on system design and complexity.  

Elastomeric seals installed in a SIP application are exposed to a combination of load, pressure and high temperature, this is when deterioration can be dramatically intensified.  As a rule of thumb, the speed of chemical reaction doubles with each kelvin rise in temperature.  Before selecting an elastomer gasket for SIP applications, producers should consider the grade of steam they require.

Clean-in-place (CIP) is another common sterilisation method, using a mix of chemicals, heat and water to sanitise equipment. Caustic Soda, Phosphoric and Nitric acids, Sodium Hypochlorite (Hypo) and Peracetic Acid (PAA) are a few chemicals used to remove in-process residues, control bioburden and reduce endotoxin levels. Complex formulations of chemicals can rapidly cause severe damage to elastomeric seals, especially in applications of load and pressure.  Chemical resistance will be the main factor producers will need to consider in CIP applications, however steam sterilisation at 140°C is commonly used after these fluids and solvents.

Perlast® Perfluoroelastomers (FFKM) have been designed to combat both high temperature and resist chemicals used in SIP and CIP procedures.

FDA-approved white Perlast® G74S (Hardness 71 IRHD, operating temperature of -15 to +260°C, UV Class I, EC 1935/2004 and EC 2023/2006) or FDA-approved white Perlast® G75S (Hardness 75 IRHD, operating temperature of -15 to +310°C, UV Class I, EC 1935/2004 and EC 2023/2006) are just two examples of high performance Perlast® grades suitable for SIP and CIP sterilisation processes.

As the food and beverage industries are seeing more stringent processes being introduced, getting the seal specification right for process equipment could save producers from the high risk of costly and damaging recalls and product liability.

Precision Polymer Engineering (PPE) design and manufactures Hyclamp® sanitary elastomer gaskets, in standard and custom sizes including ISO 2852, DIN 32676 and BS 4825.  A range of USP Class VI, FDA, 3-A, WRAS, ADI-FREE, Metal Detectable, EC1935/2004 and EC2023/2006 compliant material grades are available.

If you need further assistance with your material selection for a specific UV, SIP or CIP application, why not explore PPE’s Elastomer Compatibility & Rubber Chemical Resistance Guide or send our team a direct message.

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