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Waterproof blind rivets

Function and typical areas of application

 

Blind rivets are among the most commonly used fastening solutions, alongside screws and dowels. But what exactly does ‘waterproof blind rivets’ mean and how do they differ from conventional variants? This topic is particularly relevant for craftsmen who rely on permanently tight connections.

In this article, you will learn in a simple and understandable way how splash-proof and watertight blind rivet connections work, which products are particularly suitable and in which areas of application they show their strengths.

What makes blind rivets watertight?

Standard blind rivets do not seal completely. Moisture can penetrate through the smallest gaps. A truly watertight blind rivet is available in the form of so-called cup rivets (known as CAP® at GESIPA®). Their special design makes them airtight and watertight, although this tightness refers to the rivet itself – not necessarily to the entire connection.

In most applications, however, a splash-proof connection is sufficient. This is achieved by special blind rivet types such as:

These rivets are characterised by their technical design, in which the mandrel is firmly encapsulated in the closing head so that no water can penetrate. The PolyBulb® rivet in particular offers excellent sealing against water penetration on the back of the connection thanks to its closed closing head (see image).

The tightness of these fasteners is usually tested with a water column. Additional sealing washers, e.g. made of EPDM, can be used for further optimisation if required.

Where can water penetrate?

A blind rivet usually consists of two main components: the blind rivet and the mandrel. The blind rivet is the visible part that is inserted through the drill hole. The mandrel runs through the blind rivet and ensures the necessary deformation on the back of the workpiece during the setting process. When pulled with the blind rivet tool, the blind rivet head deforms into a mushroom shape, creating a secure connection. As soon as the required tensile strength is reached, the mandrel breaks off at a predetermined breaking point.

This design allows moisture to penetrate at various points, for example between the blind rivet head and the workpiece or through the remaining cavity in the broken-off mandrel. For this reason, special rivet shapes or additional sealing measures are required for particularly demanding applications.

Design and function

Standard blind rivets connect components to each other but do not provide a complete seal against moisture or air. Small gaps or spaces are created when the rivet is processed, through which water and moisture can penetrate. Waterproof blind rivets differ in their special design features, which ensure that they seal completely.

Materials and head shapes of blind rivets

Watertight blind rivets are usually made of stainless materials such as stainless steel (A2/A4) or aluminium (AL) to ensure reliable corrosion protection.

The blind rivet head – i.e. the visible part of the rivet – can be designed with different head shapes, such as flat head, countersunk head or dome head.

The choice of head shape influences the load distribution, the installation depth and the appearance of the connection. It also plays a role in terms of tightness: a correctly positioned rivet head can significantly reduce the penetration of moisture via the contact surface between the rivet and the material.

Geometry for tightness: How special rivets keep water out

With certain blind rivet types – such as the PolyBulb® or MegaGrip® – the special geometry ensures that the rivet body expands particularly evenly during setting. This forms a closed closing head on the back of the connection. In combination with the mandrel remaining in the rivet, this creates a very good seal against splash water, as no water can penetrate through the closing head or along the mandrel.

Step-by-step explanation of the riveting process

1. Positioning the rivet in the material
First select the appropriate blind rivet for the grip range of your components. Insert the blind rivet into the pre-drilled hole.

2. Inserting and pulling the mandrel
Use special blind rivet pliers to pull on the rivet mandrel. This pulling action deforms the rivet body on the rear side of the joint.

3. Deformation of the rivet body and sealing
Pulling the mandrel causes a mushroom-shaped bulge to form in the rivet body on the rear side of the workpiece. The integrated seal on the front presses against the material at the same time. As soon as the mandrel reaches the required force, it breaks off in a controlled manner. The blind rivet is now firmly and watertight in the material.

The watertightness is achieved by the precise adjustment of the integrated seal during the setting process. The pressure during setting ensures that the seal is absolutely tight and reliable on the workpieces.

Typical areas of application

Automotive
In vehicle construction, splash-proof blind rivet fasteners are particularly in demand – for example in underbody assemblies, wheel arches or door panels. Here, solutions such as MegaGrip® or PolyGrip® ensure robust connections despite changing weather conditions and mechanical stresses.

Construction industry and roof systems:
With SolarGrip®, GESIPA offers a specially developed solution for use on flat roofs or trapezoidal sheets – for example, when installing PV systems. The splash-proof rivet connection also ensures reliable sealing and stability for facade elements or rain gutters.

Electronics and housing construction:
MultiSwitch switching cabinet systems, outdoor housings and control boxes require particularly protected assembly. The eFast blind rivets were designed for these requirements in housing construction. They enable safe, fast processing with a high level of protection against splash water.

Ventilation and air conditioning technology / differential pressure applications:
In the ventilation industry – e.g. in systems with positive or negative pressure – connections must be particularly reliable and tight. Special rivets such as the PolyBulb® with closed closing head offer an excellent solution here.

Refrigerated vehicles:
Temperature-resistant, tight fasteners are required for the interior fittings of refrigerated and insulated vehicles. GESIPA® rivets with splash-proof design ensure that the fasteners remain functional even under changing temperature conditions.

Advantages of watertight blind rivets in comparison

Watertight blind rivets offer you important advantages over other joining technologies. When you choose watertight rivets, you benefit in several ways:

Quick and easy processing
Watertight blind rivets are just as easy to process as conventional blind rivets. All you need is a suitable blind rivet tool. Drill, insert the rivet, pull the mandrel – and your connection is permanently tight. There is no need for time-consuming additional work such as sealing with silicone or adhesives.

Corrosion protection and permanent tightness
As waterproof blind rivets are often made of rustproof materials such as stainless steel or aluminium, you benefit from excellent corrosion protection. Your connection therefore remains reliable for a long time, even in direct contact with water or salt water.

Reliability in extreme weather conditions
Whether strong sunlight, extreme cold or aggressive salt water: watertight blind rivets withstand even the toughest conditions. This makes them particularly suitable for outdoor applications.

Reduced maintenance costs
Since watertight blind rivets permanently seal the connection, maintenance costs are significantly reduced. You do not need to carry out additional sealing measures or check the connections regularly. In the long term, you save time and money thanks to lower maintenance costs.

Tips for the correct use of waterproof blind rivets

To ensure that your connection is truly waterproof, there are a few important points to consider. These tips will help you ensure that your blind rivet connection remains permanently tight and stable.

 

Selecting the right rivet size and materials
 

Select the blind rivet size that matches the diameter of the hole. Rivets that are too large or too small will not only compromise the strength but also the seal of the connection.

For outdoor use, we recommend waterproof or splash-proof blind rivets made of stainless steel or aluminium:

  • Stainless steel is particularly resistant to corrosion, chemicals and mechanical stress – ideal for aggressive environments such as shipbuilding, the construction industry or vehicle underbodies.
  • Aluminium is lighter and less expensive, but still offers good corrosion resistance – perfect for standard indoor and outdoor applications.

Avoiding typical errors

Typical errors when working with watertight blind rivets are usually caused by a lack of care during processing. Pay particular attention to the following:

  • Hole size: If the hole is too large, the seal will not be completely tight. Therefore, drill the holes exactly according to the manufacturer's specifications. At GESIPA®, we recommend drilling the hole +0.1 mm larger than the blind rivet diameter.
     
  • Insufficient setting force: Pull the rivet mandrel firmly enough to ensure that the seal is pressed optimally. Use high-quality blind rivet tools.

By observing these instructions, you will ensure optimum processing results.

Conclusion
 

Spray-proof and tight blind rivet connections are a quick and reliable solution when connections need to be protected against moisture, dirt or changing environmental conditions. Unlike conventional blind rivets, special variants such as CAP®, PolyBulb® or eFast offer a particularly high sealing effect thanks to their sophisticated geometry and high-quality materials.
 

Whether in vehicle construction, on flat roofs with PV systems, in switch cabinet construction or in differential pressure systems in ventilation technology – GESIPA® offers the right splash-proof blind rivets for every application.

When selecting a fastener, make sure you choose the right grip range, suitable materials such as stainless steel or aluminium, and precise workmanship. This will ensure that you benefit in the long term from a robust, low-maintenance and, above all, leak-proof connection.

For further information or personal advice, please refer to the wide range of products available from GESIPA® – with tailor-made solutions for your individual requirements.

Frequently asked questions

Are watertight blind rivets permanently tight?

Splash-proof or watertight blind rivets offer a high sealing effect – provided they are processed correctly. Permanent tightness depends in particular on the following factors:

  • Suitable selection with regard to material (e.g. stainless steel or aluminium)
  • Matching the clamping range
  • Careful processing, especially when drilling, positioning and setting force
     

Cup rivets such as the CAP® rivet are airtight and watertight due to their design. With splash-proof rivets (e.g. PolyBulb®, PolyGrip®), the tightness depends largely on the geometry and the setting process. A correctly set fastener offers long-lasting protection against moisture penetration.

How can the tightness be checked?

The following methods can be used to check the tightness:

  • Visual inspection: Check the rivet point for complete contact and correct setting
  • Water test: Spray the rivet point with water and observe for any leaks
  • Pressure test: Apply positive or negative pressure inside the component in combination with leak detection spray. The formation of bubbles indicates leaks.
     
  • Water column test (laboratory): Standardised procedure for determining the sealing effect at a defined water pressure

Precise testing is recommended, especially for applications in ventilation or air conditioning technology where differential pressure prevails.

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