Personal and expert advice
25 years of experience
Fast delivery times
Competitive prices
Nederlands 
Deutsch 
Français 
Knowledge base · Sizing
Tri-Clamp (clamp) connections come in three sizing systems — designated in DIN 32676 as Reihe 1 (A), Reihe 2 (B) and Reihe 3 (C). They look identical, but the tube size differs per system. What matters for compatibility is not the tube, but the flange size. Search for your size directly below.
Enter the outside diameter or inside diameter of your tube (in mm) — or a size such as “DN25” or “2″”. You instantly get the matching ferrule and the correct clamp/flange size.
Tip: type the measured tube diameter in mm. E.g. a tube of Ø33.7 mm → ISO DN33.7, flange 50.5 mm.
A Tri-Clamp ferrule is described by three dimensions. The tube diameter and wall thickness determine which tube the ferrule fits; the flange diameter determines which clamp and gasket you need.
The key insight: two ferrules with the same flange size (C) use the same clamp and gasket — regardless of whether it is a DIN, ISO or Inch tube. You choose the tube size for your line, but the flange size determines the connection.
DIN 32676 distinguishes three series. Each series uses its own tube standard, with its own way of naming the size.
Metric DIN tube (DIN 11850). The standard in the European food, dairy and pharma industries. Size is given as the nominal DN.
Example: DN25 = tube 29 × 1.5 mm, flange 50.5 mmMetric ISO tube (ISO 1127). The nominal size equals the tube outside diameter in mm. Widely used in general process industry.
Example: Ø33.7 = tube 33.7 × 2.0 mm, flange 50.5 mmImperial tube (OD tube, incl. ASME BPE). Size in inch. Common in the US and in international machine building and pharma.
Example: 1″ = tube 25.40 × 1.65 mm, flange 50.5 mmNote the example above: DN25 (DIN), Ø33.7 (ISO) and 1″ (Inch) have a completely different tube size, but the same flange of 50.5 mm. So they fit the same clamp — only the tube you weld onto differs.
Compare the systems directly: same nominal step, different tube size — but interchangeable at equal flange size (C). OD = outside diameter, ID = inside diameter, C = flange size.
| Size | OD × WT | ID | C |
|---|---|---|---|
| DN6 | 8 × 1.0 | 6.0 | 25.0 |
| DN8 | 10 × 1.0 | 8.0 | 25.0 |
| DN10 | 13 × 1.5 | 10.0 | 34.0 |
| DN15 | 19 × 1.5 | 16.0 | 34.0 |
| DN20 | 23 × 1.5 | 20.0 | 34.0 |
| DN25 | 29 × 1.5 | 26.0 | 50.5 |
| DN32 | 35 × 1.5 | 32.0 | 50.5 |
| DN40 | 41 × 1.5 | 38.0 | 50.5 |
| DN50 | 53 × 1.5 | 50.0 | 64.0 |
| DN65 | 70 × 2.0 | 66.0 | 91.0 |
| DN80 | 85 × 2.0 | 81.0 | 106.0 |
| DN100 | 104 × 2.0 | 100.0 | 119.0 |
| DN125 | 129 × 2.0 | 125.0 | 155.0 |
| DN150 | 154 × 2.0 | 150.0 | 183.0 |
| DN200 | 204 × 2.0 | 200.0 | 233.5 |
| DN250* | 254 × 2.0 | 250.0 | 268.0 |
| DN300* | 304 × 2.0 | 300.0 | 319.0 |
| Size | OD × WT | ID | C |
|---|---|---|---|
| Ø10.2 | 10.2 × 1.6 | 7.0 | 25.0 |
| Ø13.5 | 13.5 × 1.6 | 10.3 | 25.0 |
| Ø17.2 | 17.2 × 1.6 | 14.0 | 25.0 |
| Ø21.3 | 21.3 × 1.6 | 18.1 | 50.5 |
| Ø26.9 | 26.9 × 1.6 | 23.7 | 50.5 |
| Ø33.7 | 33.7 × 2.0 | 29.7 | 50.5 |
| Ø42.4 | 42.4 × 2.0 | 38.4 | 64.0 |
| Ø48.3 | 48.3 × 2.0 | 44.3 | 64.0 |
| Ø60.3 | 60.3 × 2.0 | 56.3 | 77.5 |
| Ø76.1 | 76.1 × 2.0 | 72.1 | 77.5 |
| Ø88.9 | 88.9 × 2.3 | 84.3 | 106.0 |
| Ø114.3 | 114.3 × 2.3 | 109.7 | 130.0 |
| Ø139.7 | 139.7 × 2.6 | 134.5 | 155.0 |
| Ø168.3 | 168.3 × 2.6 | 163.1 | 183.0 |
| Ø219.1 | 219.1 × 2.6 | 213.9 | 233.5 |
| Size | OD × WT | ID | C |
|---|---|---|---|
| ¼″ | 6.35 × 0.89 | 4.6 | 25.0 |
| ⅜″ | 9.53 × 0.89 | 7.8 | 25.0 |
| ½″ | 12.70 × 1.65 | 9.4 | 25.0 |
| ¾″ | 19.05 × 1.65 | 15.8 | 25.0 |
| 1″ | 25.40 × 1.65 | 22.1 | 50.5 |
| 1½″ | 38.10 × 1.65 | 34.8 | 50.5 |
| 2″ | 50.80 × 1.65 | 47.5 | 64.0 |
| 2½″ | 63.50 × 1.65 | 60.2 | 77.5 |
| 3″ | 76.20 × 1.65 | 72.9 | 91.0 |
| 4″ | 101.60 × 2.11 | 97.4 | 119.0 |
| 6″ | 152.40 × 2.77 | 146.9 | 167.0 |
Grouped by flange size (C). All sizes in the same row use the same clamp and gasket, regardless of system.
| Flange size C | DIN — Reihe 1 | ISO — Reihe 2 | Inch — Reihe 3 |
|---|---|---|---|
| 25.0 mm | DN6, DN8 | Ø10.2 · 13.5 · 17.2 | ¼″ · ⅜″ · ½″ · ¾″ |
| 34.0 mm | DN10, DN15, DN20 | – | – |
| 50.5 mm | DN25, DN32, DN40 | Ø21.3 · 26.9 · 33.7 | 1″ · 1½″ |
| 64.0 mm | DN50 | Ø42.4 · 48.3 | 2″ |
| 77.5 mm | – | Ø60.3 · 76.1 | 2½″ |
| 91.0 mm | DN65 | – | 3″ |
| 106.0 mm | DN80 | Ø88.9 | – |
| 119.0 mm | DN100 | – | 4″ |
| 130.0 mm | – | Ø114.3 | – |
| 155.0 mm | DN125 | Ø139.7 | – |
| 167.0 mm | – | – | 6″ |
| 183.0 mm | DN150 | Ø168.3 | – |
| 233.5 mm | DN200 | Ø219.1 | – |
| 268.0 mm | DN250* | – | – |
| 319.0 mm | DN300* | – | – |
* DN250 and DN300 fall outside the sanitary standard, but are available on request.
Measure the tube diameter, use the search above, or send us your dimensions. Our specialists quickly determine the right system and the correct clamp for your line.
Dimensions per DIN 32676 (Reihe A/B/C). Values are indicative; inside diameters (ID) are calculated as OD − 2 × wall thickness and may vary by manufacturer and design. When in doubt, check the product specification or contact us.