Advantages And Material Selection Of Sanitary Grade Din 11864-2 Aseptic Union Nuts And Flanges

For biopharmaceutical sterile processing, specify a din11864 aseptic nut flange with defined O‑ring compression to eliminate dead legs. Weld the male and liner parts to tube ends per DIN 11866, install the O‑ring in the flange groove, and tighten the nut to specified torque. The O‑ring fills all gaps, leaving no unswept volume. Manufactured from 316L stainless steel, standard sizes DN10–DN100, pressure up to 25 bar, temperature -10°C to +140°C. Internal surfaces polished to Ra ≤ 0.8 µm meet EHEDG and 3‑A standards.

The Dead‑Leg Problem in Aseptic Connections

Threaded or clamped connections have unswept volumes where residues stagnate, biofilm forms, and sterilization fails. These dead legs compromise batch integrity. The din11864 series addresses this with a male part, liner, and union nut holding an O‑ring independently. When tightened, the O‑ring deforms to fill the gap with no unswept volume.

Zero‑dead‑leg sealing benefits:

• 🧪 Eliminates microbial hiding places

• 🧼 Complete CIP fluid penetration

• 🔧 No threaded crevices for residue trapping

• ⚙️ Consistent O‑ring compression

• ✅ Simplified validation

din11864 Series Overview

The din11864 standard has three parts for aseptic connections:

• din 11864 1: Aseptic screwed unions (threaded)

• din 11864 2: Aseptic flange connections (nut flange)

• din 11864 3: Aseptic clamp connections

din 11864 2 provides a permanent, crevice‑free joint for high‑pressure systems. din 11864 1 suits hose connections requiring frequent disconnection. din 11864 3 enables rapid assembly for modular systems. din 11864 1 form a defines the O‑ring groove geometry and compression parameters. For permanent flanged connections, din 11864 2 is preferred.

Sealing Mechanism and form a Configuration

The din11864 system uses the same sealing principle as din 11864 1 form a—an independently held O‑ring in the flange face deforms under nut torque to create a flush seal. This eliminates dead legs by filling the gap between components with defined O‑ring compression. Nut torque ensures repeatable sealing across assemblies.

Key design features:

1. Defined O‑ring deformation for consistent sealing

2. Flush‑mounted O‑ring eliminates unswept volume

3. Butt‑weld ends for permanent, crevice‑free integration

4. Torque‑controlled nut for repeatable assembly

5. Compatible with EPDM, silicone, FKM O‑rings

Material and Surface Finish

The flange and nut are 316L stainless steel (1.4404), providing molybdenum‑enhanced corrosion resistance for saline buffers, acids, and CIP chemicals. Internal surfaces polished to Ra ≤ 0.8 µm (Class H3) meet GMP standards. O‑rings are FDA‑compliant and conform to EC 1935‑2004.

Specifications and Selection Criteria

Applications and Selection Considerations

din 11864 2 flange is used in bioreactor connections, sterile transfer lines, chromatography skids, CIP supply headers, and purified water loops.

When selecting:

• Size — DN10–DN100 matched to tube OD per DIN 11866.

• O‑Ring — EPDM for general; silicone for high‑temp; FKM for aggressive chemicals.

• Pressure — up to 25 bar standard; 40 bar for smaller diameters.

• Surface finish — Class H3 Ra ≤ 0.8 µm for pharmaceutical applications.

din 11864 2 eliminates dead‑leg risks. For systems requiring rapid disassembly, din 11864 1 is available. For modular clamp connections, din 11864 3 is specified.

Installation and Maintenance

Butt‑weld male and liner parts to tube ends per qualified procedures. Install O‑ring in the flange groove. Position nut and tighten to specified torque. Ensure no gap between flange faces—O‑ring compression must be uniform. Flange supports CIP and SIP without disassembly. Inspect O‑rings for wear every 12‑18 months.

This flange design delivers zero‑dead‑leg sealing for biopharmaceutical sterile processing. The din11864 aseptic nut flange combines 316L stainless steel, defined O‑ring compression, and flush sealing to eliminate microbial hiding places — reducing contamination risk and simplifying validation.

DIN 11864-2 Aseptic Nut Flange

• DIN 11864-2 is a gap-free connection that has been specially designed with sterile applications in mind.
• The DIN11864-2 stainless fittings are available in practically all sizes and standard configurations. With these flanges means the process conditions are optimized inside for sterility and cleaning processes whilst ensuring the highest safety to the environment.
• All DIN11864-2 aseptic stainless flanges have a smaller outer diameter and are very compact. The design of these aseptic stainless unions incorporates the use of a standard dimension o-ring which gives the flexibility of material choice.

Product Description

Product Parameter