DIN 11851 Silicone Gasket
Manufacturer & Custom Solutions

What DIN 11851 Fittings Are

DIN 11851 is the German sanitary standard for threaded pipe unions used in dairy, food, and beverage processing. Outside Germany you will hear them called "dairy couplings" or "milk thread fittings" — the German name Milchrohrverschraubung says the same thing: a fitting born in the milk industry.

The connection is simple and clever. A complete union has four parts: a male threaded part (welded to one pipe), a liner (welded to the other pipe), a round slotted nut, and a D-section gasket. The gasket sits on the conical face of the male part; the nut screws onto the round thread and pulls the liner tight against it, compressing the gasket into a hygienic seal. No tools beyond a hook wrench, no bolt pattern, no alignment problems — the round thread and generous tolerances make this one of the most forgiving sanitary connections ever designed.

DIN 11851 Gasket Dimensions

The gasket size follows the DN number of the union. Standard D-section gasket dimensions (mm):

Fit matters as much as size. In a sanitary union, the gasket must sit exactly in its seat — a gasket that overhangs into the product flow creates a step where bacteria can grow and cleaning fluid cannot reach. A gasket that is too small leaves a crevice on the outside. Both fail a hygiene audit.

That is why ZSR manufactures every DIN 11851 gasket to standard dimensions with tight ID and OD control — and with smooth, glossy surfaces straight from the mold. A glossy, pore-free surface gives bacteria nowhere to hold on, releases product residue easily during cleaning, and keeps the seal hygienic through years of washdown cycles. Standard sizes from DN10 to DN150 are kept in stock for fast delivery.

Sanitary Grade Requirements

A gasket in a food line is a food-contact part — full stop. Here is how we build ours:

Platinum-cured FDA food grade silicone — our standard. Every ZSR DIN 11851 silicone gasket is made from platinum-cured compound complying with FDA 21 CFR 177.2600. Platinum curing leaves no chemical by-products in the rubber, so the gasket adds no taste, no smell, and no color to milk, beer, juice, or any other product. EC 1935/2004 compliant material is available for European customers.

Metal detectable option for HACCP-critical zones. If a gasket fragment ever enters the product, a metal detector must catch it. Our metal detectable silicone (standard blue) is picked up by standard inline detectors — the extra layer of protection your HACCP plan asks for.

Built for CIP and SIP. These gaskets live a hard life: daily caustic and acid CIP washdowns, plus steam-in-place cycles up to 123°C. Our food grade silicone stays flexible through hundreds of cleaning cycles without hardening, cracking, or taking a permanent set — which means fewer gasket changes and fewer line stoppages.

Other materials are available if your line needs them — EPDM for high-acid service, NBR for fatty products, FKM and PTFE for aggressive chemicals. Tell us your product and your cleaning regime, and we will confirm the best material.