IDF FITTINGS

IDF fittings, which stands for International Dairy Federation, are a widely used type of hygienic stainless steel pipe coupling in the UK and Europe.

They are distinguished by their wide hexagon nut and unique T-shaped seal, which ensures a smooth, crevice-free internal bore for highly sanitary applications.

Key Features and Specifications

Standards: IDF fittings are manufactured in accordance with British Standard BS 4825 Part 4 and ISO 2853.
Material: All "wetted" parts (the male part and liner that contact the product) are made from Grade 316 or 316L stainless steel for superior corrosion resistance. The external hexagon nut is made from Grade 304 stainless steel.
Crevice-Free Design: The T-shaped (or sometimes L-shaped) joint ring fits flush with the tube's bore, eliminating potential "bug traps" and making the fitting suitable for Clean In Place (CIP) systems.
Pressure Rating: They are designed to operate up to a maximum working pressure of 16 Bar (1.6 Mpa) at ambient temperature.
Size Range: Available in standard imperial tube sizes, typically from 1 inch to 4 inches, though some suppliers offer up to 6 inches.

Components of an IDF Union

A complete IDF union comprises four main parts:

Hexagon Nut: A large, hexagonal nut that threads onto the male part to secure the connection. A round slotted nut is also an option for added security against unauthorised dismantling.
Weld Male: The externally threaded part designed to be welded onto a pipe end.
Weld Liner: A part that fits inside the male and provides the sealing face, also with a spigot end for welding to the other pipe section.
Hygienic Seal (Gasket): The T-shaped joint ring, commonly available in:

Nitrile (NBR): The standard material, suitable for general food and beverage applications.
EPDM: Ideal for high temperatures, hot water, and steam, often used in CIP systems.
Viton® (FKM): For enhanced chemical resistance.

PTFE: For extreme chemical inertness.