Sanitary fittings are known in the industry under several names. These include, but may not be limited to, sanitary flange, sanitary coupler, ferrule, tri-clamp, tri-clover, hygienic union, or sometimes just TC for short.
A sanitary connection is made by attaching two sanitary flanges with a gasket between them using a flange clamp. The clamp used to hold the two flanges and gasket together can be referred to as a sanitary clamp, hygienic clamp, tri-clamp union, and at times, the tri-clamp. These fittings are offered in a range of shapes and sizes by a variety of different companies. They are very common in all areas of biopharmaceutical production, not to mention widely used in other industries such as food and beverage, cosmetic and personal care. These types of fittings were designed for enhanced cleanability without pockets, tight bends or threading to limit potential entrapment areas where bacteria could accumulate.
Sanitary fittings are offered in both stainless steel and plastic configurations. For the purposes of this blog, only the plastic fittings and options that Qosina offers will be described. These components enhance flexibility by allowing single-use technologies to be connected to stainless-steel equipment, as well as to other single-use systems. They are used in simple transfer lines, as distal connectors on bag lines, and in complex filtration assemblies. These connectors are typically designed to ASME BPE (The American Society of Mechanical Engineers, Bioprocessing Equipment) standards, which allows for connection between different manufacturers’ components.
Plastic sanitary flanges for single-use systems have historically come in two common sizes, referring to the flange end of the component: the 1/4, 3/8, 1/2 and 3/4 inch, 0.5 inch/0.75 inch (mini or fractional flange) and the 1 inch/1.5 inch (maxi or standard flange). Commonly, opposite the flange side will be a hose barb allowing for tubing installation with a retention device (cable tie, Oetiker® clamp, etc). As sanitary flanges have gained popularity, additional flange sizes are now available, such as 2 inch and 3 inch sanitary flange-to-hose barb fittings. Larger sized (3, 4, 6 and 8 inch) plastic flanges have typically been used for other connections such as connecting a powder bag to a mixing system. Hose barbs on sanitary flanges range from 0.125 inches (1/8) to 1.5 inches (1 1/2) for a tubing connection, with the 1.5 inch hose barb connections being more recent.
Connectors with sanitary flanges on both ends are also available. They act as adapters, allowing for a reduction in flow path with the same flange size, or allowing for a change in flange diameter as seen in concentric reducers. Sanitary flanges are also present on other types of connectors such as bag ports, which are sealed directly to bag film, on aseptic and quick disconnect connectors, as well as steam-in-place (SIP) connectors such as the Steam-Thru® and Lynx® ST components. These allow for sterile connections between pre-sterilized single-use technologies and stainless-steel process equipment.
Sanitary Flange Gaskets
Gaskets for single-use applications are typically made of silicone and are placed between two mating non-gendered sanitary flanges and connected with a sanitary flange clamp. Once clamped together, the gasket serves as a method of keeping a tight seal. There are some sanitary flange components that offer the gasket pre-installed, which has advantages such as ensuring proper gasket alignment, easier installation of the clamp and ultimately reduced risk of contamination. Gaskets for 0.5 inch/0.75 inch and 1 inch/1.5 inch are readily available and will fit most configurations of sanitary flanges. Other sizes, up to and including 8 inch, are also readily available.
Sanitary Flange End Caps
Often, the sanitary flange end needs to be closed until making a connection. To preserve the cleanliness of the open end, an end cap with a gasket and clamp can be placed on the open sanitary flange. Caps that fit the 0.5 inch/0.75 inch mini and 1 inch/1.5 inch standard flanges are most frequently used, but sizes that fit up to 4 inch flanges are available.
Sanitary Flange Clamps
A sanitary flange clamp, also known as a hygienic clamp or tri-clamp union, is needed to hold together the two sanitary flanges with a gasket. There are a variety of different clamp configurations that exist. When selecting a clamp, ensure it provides a strong hold of the flanges and gasket so there is no potential for a leak. Secondly, the clamp should be easy to connect and easy to disconnect. Options exist for one-handed installation to ease the assembly process. In some pharma scenarios, there is a need to clamp the flanges together and prevent them from unclamping. If this is required, there are sanitary clamps that enable the use of a cable tie to secure the clamp in a closed position, preventing inadvertent or tamper-evident disconnections. Additional options are available for non-reopening clamps that require the use of specific tools to reopen.
Molded Sanitary Flange Components
Molded sanitary connections function as an alternative to sanitary flange components and consist of a molded gasket, backing cup and tubing, forming one component. This eliminates the need for barbed connections and retention devices such as cable ties and reduces risk of leaks and bioburden entrapment issues associated with barbed fittings. The integrated gasket eases the installation process and eliminates the need for additional components. They are typically available in 1 inch/1.5 inch standard and 0.5 inch/0.75 inch mini flange sizes. Most use either a polysulfone (PSU) or stainless-steel backing cup for the clamping surface and are offered in a variety of tubing sizes and materials (silicone, braid-reinforced silicone and thermoplastic elastomer [TPE]). These components are typically made-to-order, which could add additional lead time before integrating into a single-use assembly. Qosina offers many varieties in stock, with 6 feet of tubing, allowing these to be cut to length before incorporating into a design.
Sanitary flanges are offered in animal-free polypropylene (PP) and polyvinylidene fluoride (PVDF), also known as Kynar. In most pharma settings, PP works well and is a more affordable option. If additional chemical resistance is needed, Kynar can be used. Gaskets are offered in silicone, and sanitary flange clamps are most widely offered in glass-filled nylon. However, with prior supply chain interruptions, these are now offered in polybutylene terephthalate (PBT). Options are also available in polyketone (PK).
Qosina offers a wide variety of sanitary flanges, caps and gaskets, sanitary flange clamps, and molded sanitary components to meet our customers’ needs. We have a full line of components for all single-use bioprocessing connections needed in a variety of pharmaceutical settings. Please visit our website at www.qosina.com or our bioprocess application page at www.qosina.com/bioprocess to see all available options.