When installing pipe networks it is vitally important to select the right seal for any penetrations in the system, as a poorly chosen seal can lead to costly maintenance and disruptions to operations. 

There are several variables operators must take into careful consideration when selecting a seal, including the material of the pipe they are working with and the surrounding environment. Here, we take a look at two types of seals – non-mechanical seals and link-seals – to see what applications they suit best. 

 Pipe systems transport fluids and other substances through pipes in a network and often these pipes pass through walls and various spaces in a facility. The annular space created between the openings and the pipe must be sealed to prevent the passage of gases, airborne particles, liquids, pests and even fire from one area to another where it can cause leaks, contamination or create hazards for equipment or employees. 

There are two main options when it comes to penetration seals: mechanical and non-mechanical. Each comes with its own pros and cons and it is up to users to consider which option is best for their particular operation. 

Non-mechanical seals  

Simple non-mechanical seals include putties, grouts, sealants, caulks and epoxies. These seal types have the ability to conform to any shape in order to fill a void and are relatively inexpensive, making them a tempting choice to seal penetration gaps. 

A downfall of these sealants is that they do not typically maintain sufficient adhesion or pliability over time and can often become brittle. Their lack of movement capability and inability to withstand movement and vibration makes them a poor choice as a long-term solution in many situations. 

Additionally, with these kinds of traditional methods installation and application are often messy and require significant dry time, leading to costly system downtime and a potential loss of productivity. 

What are link-seals? 

Link-seals are a type of mechanical seal that are supplied in a belt form with a series of interconnecting rubber links, pressure plates and bolts that – when tightened – create a gas, air and watertight seal between the pipe and core hole.  

 Link-seals are a wise choice for many industrial operations due to their superior sealing qualities. When the seal’s bolts are tightened the pressure plates compress the rubber links, causing them to expand and press against the penetrated surface and the pipe. The resultant pressure and frictional forces create a tight seal.  

Link-seals are highly durable and corrosion resistant, requiring minimal maintenance post-installation.  

The seals are also easily installed, requiring no special equipment or tools; one person with a simple hand wrench can install a link-seal and, once finished, the mechanism will instantly provide sealing for the penetration – requiring no setting or drying time, unlike other more traditional sealants.  

This process also lends itself to efficient maintenance, as the link-seal can easily be checked, adjusted, removed and reinstalled following initial installation. In fact, a link-seal can even be reused on a different penetration of a similar size.  

Choosing the right seal for your system 

When choosing between mechanical link-seals and non-mechanical options, it’s important to consider the unique aspects of an operation. Firstly, it is critical to consider the type of environment or chemicals that may contact the seals – if it is corrosive or abrasive, mechanical seals are a better choice as they can be selected to handle a wide range of substances.  

Link-seals are also the better option for systems that are prone to vibration, as the rubber links are capable of withstanding certain levels of movement. Grouts and other cementitious sealants are susceptible to damage from vibration and movement, making them a poor choice for many pump operations.  

One potential issue facing link-seals is the alignment of the pipe. For the rubber links to create a high-quality seal, the pipe must be centred within the penetration opening so that the space between the pipe and penetrated surface is close to equidistance around its circumference. Non-mechanical sealants can fill spaces regardless of alignment and therefore can offer a more attractive option for awkwardly placed penetrations.  

Cost is another major difference between the two options, as link-seals are typically more expensive than non-mechanical sealants – meaning a higher upfront cost. In spite of this, link-seals seal instantly, last longer and require less frequent maintenance, allowing for potential cost savings. The ability to remove and reinstall can result in reduced downtime for maintenance or equipment changes, making link-seals a superior choice for operations where downtime is critical.   

Link-seals on the market 

 Just as there is no one-size-fits-all system, companies such as Projex Group offer a wide variety of link-seal products to suit a range of systems, fluids and environments.  

These include:

Prjex Link-seal 'C' black stainless steel fittings. Image credit: Projex

Projex Group Link-seal Model ‘S316’.

Link-Seal Model ‘S-316’ (EPDM)  

The model ‘S-316’ is suitable for use in water, direct ground burial and atmospheric conditions and provides electrical isolation where cathodic protection is necessary. Due to its stainless-steel hardware, it is a good choice for applications like chemical processing and wastewater treatment.

Projex Link-seal 'O' model, oil resistant scaled. Projex Link-seal 'C' black stainless steel fittings. Image credit: Projex

Projex Group Link-seal Model ‘O’.

Link-Seal Model ‘O-S316’ (Nitrile) 

The model ‘O’ is highly resistant to oils, fuels and other solvents, making it an ideal choice for use with gasoline, motor oil, kerosene, jet fuel, methane, hydraulic fluid and more. The O-S316 model uses stainless steel hardware which makes it suitable for corrosive environments.

Projex Link-seal 'T' model.

Projex Group Link-seal Model ‘T’.

Link-Seal Model ‘T’ (Silicone) 

The high temperature Link-Seal Model-T has achieved two hours fire rating according to Australian Standards 1530.4 and 4072.1. It can handle temperatures ranging between minus 55 to more than 204°C (minus 67 to more than 400°F).  Model T can be used to provide a fire rating but also a positive hydrostatic seal against water or gas at the same time. 

Projex Link-seal Model 'L'.

Projex Group Link-seal Model ‘L’.

Link-Seal Model ‘L’ (Low Durometer EPDM)  

The Low Durometer Model ‘L’ is designed for use with thin wall metal pipes, applications using plastic, ceramic or glass pipe, or in applications where the pipe might be fragile and incapable of withstanding the compressing forces of a standard link-seal.

While non-mechanical sealants have their advantages and can often be the practical choice for simple, low-intensity systems, link-seals offer superior resilience and efficiency, making them the smarter choice for industrial operations.  

Featured image: Water tank sealed with Projex Group Link-seals. Images credit: Projex Group.

This sponsored editorial is brought to you by Projex Group. Find out more about link seals at

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