STAUFF Safety Lock Washer (Type SI DIN 93 – Heavy Series)
The STAUFF Safety Lock Washer (Type SI DIN 93 – Heavy Series) is a mechanical locking device designed to prevent Type AS hexagon head bolts from loosening. Featuring a single tab in accordance with DIN 93, it ensures clamp stability by locking mechanically between the component body and the bolt head. It is available in zinc/nickel-plated carbon steel (W3) or V4A stainless steel (W5) for demanding and corrosive hydraulic applications. The available product codes are: SI-10.5-DIN93, SI-13-DIN93, SI-17-DIN93, SI-21-DIN93, SI-25-DIN93, SI-31-DIN93.
Safety lock washers, specifically the STAUFF Safety Lock Washer (Type SI DIN 93 – Heavy Series), are used in industry as essential mechanical locking devices. Their primary purpose is to effectively and safely prevent the accidental loosening of Type AS hexagon head bolts under operating conditions. The locking principle is based on a specific bending action during installation. The installer must physically bend the tabs of the component: the longer tab of the washer must be bent downwards so that it rests directly against the side of the clamp body. At the same time, one side of the washer itself is bent upwards until it sits against one of the flat faces of the hexagon bolt head, thereby creating a mechanical anti-rotation lock.
This specific series, identified as Type SI, is configured with a single tab in strict compliance with the DIN 93 technical and dimensional standard. The product range includes two main construction material codes, designed to ensure maximum strength and durability depending on the industrial operating environment in which the clamps are installed. The first option, identified by material code W3, is manufactured from solid carbon steel and features a protective zinc/nickel-plated coating designed to provide high corrosion resistance. Alternatively, the W5 material version is available for more aggressive environments or applications requiring superior stainless properties. This variant is manufactured from V4A stainless steel in grades 1.4401 and 1.4571, corresponding to the international AISI 316 and 316 Ti designations. Alternative materials and surface finishes are available upon specific request.
The STAUFF Safety Lock Washer (Type SI DIN 93 – Heavy Series) is specifically designed for use in hydraulic fastening systems officially classified as the “Heavy Series” in accordance with DIN 3015, Part 2. From a dimensional perspective, this component is designed to be compatible with STAUFF Groups 3S to 12S, corresponding to DIN size Groups 1 to 10. The technical design ensures complete coverage of the fastening sizes, with precise inside diameters, indicated as dimension ØD1, varying according to the relevant group: from a minimum of 10.5 mm for STAUFF Groups 3S, 4S and 5S, through 13 mm, 17 mm, 21 mm and 25 mm, up to a maximum inside diameter of 31 mm for the larger Groups 10S, 11S and 12S. The use of standardised dimensions ensures a perfect fit within clamp systems.
| Feature | Value |
|---|---|
| Washer Type | Safety lock washer with 1 tab (Type SI) |
| Reference Standard | DIN 93 / DIN 3015, Part 2 (Heavy Series) |
| Primary Function | Prevention of loosening of Type AS hexagon head bolts |
| Material W3 | Zinc/nickel-plated carbon steel |
| Material W5 | V4A Stainless Steel 1.4401/1.4571 (AISI 316/316 Ti) |
| Inside Diameters (D1) | 10.5 mm | 13 mm | 17 mm | 21 mm | 25 mm | 31 mm |
| Group Compatibility | From STAUFF 3S (DIN 1) to STAUFF 12S (DIN 10) |
| Base Product Code | Compatible STAUFF Groups | Compatible DIN Groups | Inside Diameter (D1) |
|---|---|---|---|
| SI-10.5-DIN93-* | 3S, 4S, 5S | 1, 2, 3 | 10.5 mm |
| SI-13-DIN93-* | 6S | 4 | 13 mm |
| SI-17-DIN93-* | 7S | 5 | 17 mm |
| SI-21-DIN93-* | 8S | 6 | 21 mm |
| SI-25-DIN93-* | 9S | 7 | 25 mm |
| SI-31-DIN93-* | 10S, 11S, 12S | 8, 9, 10 | 31 mm |