Sanitary Weldable Butterfly Valve in 316L Stainless Steel — 3A Type, EPDM or Viton

Cematic's sanitary weldable butterfly valve in 316L stainless steel is the standard fluid control component in sanitary installations where the connection is permanent by butt welding. Unlike the version with a removable clamp connection, this valve is welded directly to the process piping.

This eliminates all mechanical joint points that could be sources of leakage or contamination. Furthermore, its 3A Type certification guarantees compliance with the most demanding hygiene standards in the food, pharmaceutical, and beverage industries.

It is also available with two seat options. EPDM covers applications up to 110 °C and Viton up to 200 °C. Consequently, a single valve platform covers everything from standard food processes to full-temperature SIP sterilization.

Operating Principle — Sanitary Weldable Butterfly Valve

The disc rotates 90° between the fully open and fully closed positions. Standard operation is manual via a lever, so it does not require electrical or pneumatic power. It is also the simplest option to install and operate. The Viton seat variant also includes a multi-position lever, which allows flow adjustment in intermediate positions and locking the valve in the desired position.

Thanks to the weldable ports, the joint between the valve and the pipe is permanent and without mechanical gaskets. Consequently, product retention points and leakage risks that exist in clamp or threaded connections are eliminated. Thus, it is the preferred connection in aseptic lines where circuit integrity is critical.

Weldable vs. Clamp — when to choose each connection

The choice between weldable and clamp connection depends on the type of installation and maintenance requirements. Therefore, it is important to define it before specifying the valve. The weldable connection is correct in the following cases:

• Permanent installations: When the valve will not be frequently disassembled, welding offers greater integrity than clamping, as it eliminates the risk of leaks due to gasket deterioration or clamp loosening.
• High-purity aseptic lines: The welded joint has no cavities or external gaskets. Therefore, it is the standard connection in systems where external contamination is unacceptable.
• Reduction of leak points: In installations with many valves, welding reduces the total number of mechanical joints. This simplifies preventive circuit maintenance.

The clamp connection, on the other hand, is correct when the valve needs to be frequently disassembled for inspection or off-line cleaning. For this application, see the sanitary clamp butterfly valve →

Construction Materials

The body and disc are made of 316L stainless steel, which is the standard material in hygienic applications, as it offers greater resistance to chlorides and cleaning agents than SS304. The seat is available in EPDM or Viton, depending on process requirements. This allows the valve to be adapted to different temperature conditions and chemical compatibility.

Finally, the ports are butt-weldable to stainless steel piping of the same diameter. This ensures material continuity throughout the process line.

Technical Specifications

Seat Selection — EPDM or Viton

The seat defines the maximum temperature and the actual chemical compatibility of the valve, making it the most important decision when selecting this valve:

• EPDM (-20 °C to 110 °C): Compatible with water, low-temperature steam, dilute acids and alkalis, and standard CIP agents. Therefore, it is the most common seat in food and pharmaceutical processes that do not exceed 110 °C. It is also available in all diameters from 1/2" to 8".
• Viton (-20 °C to 200 °C): For full-temperature SIP sterilization, essential oils, or solvents incompatible with EPDM, Viton is, however, the correct option. Its availability is limited to diameters from 1" to 2". It also includes a multi-position lever for flow regulation.

Fluid Compatibility

This sanitary weldable butterfly valve is compatible with the most common fluids in the sanitary and chemical industries. The main groups are described below:

• Purified water and water for injection (WFI) — SS316L does not contribute metallic ions; therefore, it is the standard material in high-purity pharmaceutical lines
• Clean steam — up to 110 °C with EPDM, up to 200 °C with Viton — welding eliminates leak points that exist in clamp joints at SIP sterilization temperature; also, SS316L resists condensate without corrosion
• CIP agents — caustic soda, nitric acid, peracetic acid — SS316L and both seats are compatible with the most common CIP agents; however, verify concentration and temperature with Cematic's technical team for extreme conditions
• Food products — dairy, juices, beer, vegetable oils — SS316L meets food contact requirements under the 3A Type standard; in addition, welded ports eliminate product retention cavities
• Moderately aggressive chemical fluids — acids and alkalis compatible with SS316L; however, for aggressive solvents or highly corrosive fluids, consult Cematic's technical team

Applications of the sanitary weldable butterfly valve

Food and Beverage Industry

The sanitary weldable butterfly valve controls flow in food and beverage production lines where the welded connection guarantees circuit integrity during the process.

SS316L and the 3A Type standard ensure compliance with food safety requirements. Therefore, it is the preferred component in plants with FSSC 22000 or BRC certification. In addition, welded ports eliminate product retention points that do exist in clamp connections.

Pharmaceutical and Biological Industry

In the production of medicines and biological products, process sterility is, therefore, a critical requirement. Therefore, the welded connection is the preferred type of joint in aseptic lines. It also eliminates mechanical gaskets, which are microbiological risk points. Furthermore, the Viton seat allows SIP sterilization cycles up to 200 °C without seal degradation.

Purified Water Treatment

In water purification and distribution systems, this valve regulates flow without contaminating the fluid. Likewise, it is the standard component in purified water loops. Consequently, it is the standard component in purified water loops where the purity of the material in contact is a regulatory requirement. In this way, SS316L ensures that no metallic ions are introduced into the process water.

Chemical Industry

In chemical processing plants with corrosive fluids, the SS316L body offers greater resistance than SS304. In addition, its resistance to chlorides and oxidizing agents is superior. Therefore, it is the correct option in permanent installations where frequent connection maintenance is not feasible. Furthermore, welded ports eliminate the risk of leaks at connection points that, over time, affect installation safety.

For the complete range of sanitary butterfly valves, see sanitary butterfly valve collection →

EPDM Technical Data Sheet

Viton Technical Data Sheet