Hygienic Bolts
Hygienic Domed Hexagon Head Bolt——VTS28Pronounced self-draining domed head
Hygienic Design slightly domed Hexagon head Bolt——VTS29Slightly domed low-profile head
The VAYTRON hygienic bolt range brings together two 3-A-certified models for exposed fastening points on food, beverage and pharmaceutical equipment. VTS28 features a pronounced, self-draining domed head, while VTS29 uses a slightly domed, low-profile head for compact assemblies.
Both models are machined from AISI 316L stainless steel and are available with matte or polished surfaces. Blue HNBR or EPDM sealing rings support a cleanable, visible mounting transition when the bolt is correctly installed on a suitable contact surface.
Compare VTS28 and VTS29 Hygienic Bolts
| Model | Head profile | Recommended use | Key distinction |
|---|---|---|---|
| VTS28 Hygienic Domed Hexagon Head Bolt | Pronounced domed head | Exposed fastening points receiving direct washdown or CIP/SIP cleaning | Self-draining external form with clear access for visual inspection |
| VTS29 Low-Profile Hygienic Bolt | Slightly domed, low-profile head | Compact equipment assemblies where head height and clearance matter | Reduced projection above the mounting surface |
Choose VTS28 where runoff and a pronounced hygienic exterior are the main priorities. Choose VTS29 where the fastening point must remain compact without introducing a recessed top cavity.
Metal-to-Metal and Seal-Free Options
Through our discussions with pharmaceutical equipment manufacturers, we have found that elastomer seals are unsuitable for some high-temperature sterilization and cleaning processes. However, these applications may still require sealing at the fastening point.
- Hygienic screw with a metal-to-metal seal: This option uses a metal-to-metal sealing design and requires the sealing contact surface to be precisely finished to Ra < 0.8 µm.
- Hygienic screw without a seal: This option is available for applications where sealing is not required.
Hygienic Design Features
Conventional bolt heads can introduce difficult-to-clean recesses and an unsealed transition between the fastener and the mounting surface. VAYTRON hygienic design bolts use smooth exposed geometry and a blue sealing ring to make this area easier to wash, inspect and maintain.
- Smooth exposed surfaces: The domed or slightly domed head has no recessed top cavity where cleaning liquid or residue can collect.
- Sealed mounting transition: With correct, even compression, the sealing ring closes the transition between the bolt head and the mounting surface.
- Cleanable stainless steel: AISI 316L stainless steel supports corrosion resistance in demanding washdown environments.
- Visible inspection area: The exposed head and seal perimeter remain accessible during routine post-cleaning checks.
The mounting face must be clean, flat and suitable for consistent seal compression. Surface condition, installation and the complete assembly design all affect the final sealing result.
Materials, Finish and Sealing Ring Options
| Item | Specification |
|---|---|
| Bolt body | AISI 316L stainless steel / EN 1.4404 |
| Certification | VTS28 and VTS29 are 3-A certified |
| Surface finish | Matte or polished, Ra < 0.8 µm |
| HNBR sealing ring | Blue, FDA-compliant material, 85 ±5 Shore A, -25 °C to +150 °C |
| EPDM sealing ring | Blue, FDA-compliant material, 85 ±5 Shore A, -40 °C to +120 °C |
| Recommended seal-contact surface | Ra 0.8 µm or better |
FDA compliance applies to the sealing-ring material, not to the complete fastener or installed assembly. Seal suitability should be confirmed against the actual cleaning medium, temperature, pH and exposure conditions.
How to Select a Hygienic Bolt
Use the following information to identify the appropriate model and configuration:
- Head profile and available clearance: Select the pronounced VTS28 dome for exposed washdown areas or the lower VTS29 profile for compact assemblies.
- Thread and bolt length: Check the dimensional table on the relevant product page rather than relying on one range for the complete category.
- Surface finish: Choose matte or polished according to the equipment finish, inspection requirements and cleaning environment.
- Sealing method: Select HNBR or EPDM where an elastomer seal is suitable, a metal-to-metal sealing design for applicable high-temperature processes, or a seal-free version where no sealing function is required.
- Mounting surface: Confirm that the contact face is clean, flat and has a surface roughness of Ra 0.8 µm or better.
- Documentation requirements: State any drawing, material, inspection or certification requirements when requesting a quotation.
No universal tightening torque should be applied across all sizes and installations. Installation values must be determined for the selected bolt, joint and mounting conditions.
Typical Applications
VAYTRON stainless steel hygienic bolts are intended for exposed fastening points where cleanability, washdown access and visual inspection are important. Typical applications include:
- food processing and packaging machinery;
- dairy and beverage filling equipment;
- pharmaceutical and biotechnology equipment;
- guards, covers, frames and stainless steel panels;
- conveyor and product-handling systems;
- motors, gearboxes and compact drive assemblies;
- equipment exposed to routine washdown or CIP/SIP cleaning.
VTS29 is commonly used around IP69K-rated stainless steel gearboxes and motors where a lower head profile helps preserve clearance. IP69K applies to the complete gearbox, motor or enclosure—not to the bolt itself.
Frequently Asked Questions
What is the difference between a hygienic bolt and a conventional bolt?
A hygienic bolt uses a smooth external head and a sealing ring at the mounting transition. This makes the exposed fastening point easier to clean and inspect than a conventional bolt with recessed features or an unsealed head-to-surface gap.
What is the difference between HNBR and EPDM seals?
Based on our market observations, HNBR seals are common in food-processing equipment and EPDM seals in pharmaceutical equipment. For other applications, contact us to confirm the suitable material.
Are the complete bolts FDA compliant?
FDA compliance applies specifically to the blue HNBR or EPDM sealing-ring material. It should not be interpreted as FDA certification or compliance of the complete bolt or installed assembly.
Are VTS28 and VTS29 3-A certified?
Yes. Both current VAYTRON hygienic bolt models are 3-A certified. Documentation for the selected model can be requested during the quotation process.
