Core Design And Sealing Of Aseptic Connectors

A DIN 11864 aseptic union maintains seal integrity during side loads and pipe flexure through defined seal preload and crevice-free geometry. The O-ring sits in a precision groove that centers the sealing element and limits compression to a predetermined range. Three connection types and two Form variants cover different application needs. Selection requires matching connection type, Form variant, surface finish, and pressure rating.

How to select a DIN 11864 aseptic union

1. Determine connection type: DIN 11864-1 (screwed) for frequent disassembly, DIN 11864-2 (flanged) for high pressure, DIN 11864-3 (clamp) for quick changeover.

2. Choose Form: Form A (standard) for most applications, Form B for special assembly.

3. Specify surface finish: H3 (Ra < 0.8 μm) for food, H4 (Ra < 0.4 μm) for pharmaceutical.

4. Verify pressure rating based on size: DN 10-40 at 25 bar, DN 50-100 at 16 bar.

Common Design Pitfalls – Why and How to Avoid

• ❗ Using wrong Form variant: Form A and Form B have different O-ring groove profiles; not interchangeable. → DIN 11864-1 Form A is standard.

• ⚠️ Incorrect O-ring material: EPDM suitable for -40°C to +90°C; FEP handles -60°C to +160°C. → Select based on temperature and chemical compatibility.

• 🔧 Misaligned welding ends: Creates stress points and leakage paths. → Extended welding ends support orbital welding.

• 📐 Ignoring surface finish: Internal surfaces must meet Ra < 0.8 μm (H3) or Ra < 0.4 μm (H4). → Specify based on industry requirement.

DIN 11864 Standards Overview – Three Connection Types

A din 11864 1 union (screwed connection) consists of threaded ferrule, liner, and union nut with O-ring in liner groove. A din 11864 2 flange connection is bolted for larger diameters and higher pressure ratings.

For pharmaceutical applications, surface finish should conform to ASME BPE SF4 (Ra < 0.4 μm) in addition to DIN 11864 H4 requirements. Seal materials should be tested per USP 87/88 for biocompatibility. Hygienic design should follow EHEDG guidelines.

Seal Preload and O-Ring Containment – The Core Design Principle

• Defined preload: O-ring compressed to specific percentage of cross-section, ensuring consistent sealing force.

• Containment groove: Centers O-ring and prevents extrusion under pressure or side load.

• Positive stop: Metal flanges contact each other, limiting compression and preventing permanent set.

• Crevice-free design: Eliminates gaps where O-ring could extrude or migrate during thermal cycling.

Form A vs Form B Configurations

DIN 11864-1 Form A is the standard assembly with threaded ferrule, liner, and union nut. O-ring groove machined into liner. A din 11864 1 form a connection is the standard choice for most pharmaceutical applications.

DIN 11864-1 Form B uses a liner with separate retaining ring for O-ring. A din 11864 1a (Form A) is more common; Form B specified for special assembly requirements.

Critical note: Form A and Form B are not interchangeable due to different groove profiles. Using the wrong combination prevents proper O-ring seating.

Materials, Surface Finish, and Pressure Ratings

Body Material:

• 1.4404 (316L) or 1.4435 (316L) stainless steel

• Optional: Titanium, Hastelloy for aggressive media

Surface Finish:

• Standard hygienic (H3): Ra < 0.8 μm

• Pharmaceutical (H4): Ra < 0.4 μm

Seal Materials:

• EPDM: -40°C to +90°C, short-term +140°C

• FEP: -60°C to +160°C, short-term +205°C

Pressure Ratings (DIN 11864-1):

Applications with Technical Specifications

Pharmaceutical: WFI systems, pure steam, API synthesis, sterile filling. Specifies 316L, Ra < 0.4 μm (H4), USP Class VI seals, ASME BPE SF4 compliance.

Biotech: Cell culture, fermentation, chromatography. Requires 316L, Ra < 0.8 μm (H3), FDA-compliant EPDM/FEP, EHEDG certification.

Food: High-purity dairy, beverage, aseptic packaging. Uses 316L, Ra < 0.8 μm (H3), FDA EPDM, 3-A Sanitary compliance.

Selection

Installation torque: 30-50 N·m (DN 10-25), 50-80 N·m (DN 32-50). O-ring replacement: every 500 cycles or annually. Form A and Form B not interchangeable—specify Form A for standard service.

ASME BPE SF4, USP 87/88, EHEDG, and 3-A Sanitary provide design and testing standards. A din 11864 1 union suits frequent disconnection. A din 11864 2 flange suits high-pressure applications. A din 11864 1 form a connection is standard for pharmaceutical assembly. A din 11864 1a (Form A) is specified for most sterile applications.

DIN 11864-1 Aseptic Union

• DIN11864 aseptic fittings meet the exacting needs of food, chemical and pharmaceutical industries.
• Available with optional lengths to suit Orbital and Manual Welding, these unions have been designed to match tube and pipe specifications in DIN 11850; ISO 2037, ASME BPE 2002 and BS 4825 Part 1 and also ISO 1127 for schedule pipe.
• DIN11864-1 union consists of four parts: Nut, Male, Liner and Gasket.

Product Description

Product Parameter