Needing assistance with the right lining materials?

It is critical to understand the project’s needs and parameters. When collaborating with FLSI, for example, our decades of lining materials knowledge and installation services provide us an advantage that others do not have. Having said that, our experience in the lining sector since 1983 has enabled us to collaborate with the world’s leading material producers and design engineers. This has also given us the capacity to think outside the box on numerous projects, saving the customer not just money but also time. Contact FLSI today to review your project’s design and specifications and get advice on the appropriate material for your project.


GCL (Geosynthetic Clay Liner)
RPP (Reinforced Polypropylene)


What is Radio Frequency welding?

Radio Frequency (RF), dielectric or high-frequency (HF) sealing is the process in which electromagnetic energy and pressure are used to permanently join similar and sometimes even dissimilar flexible polymers together. This welding process causes the material molecules to become highly active with one-another and the result is a permanent weld. This welding process is favored by many flexible plastic fabrication companies and customers for the finish and overall longevity of the weld.

How does Radio Frequency welding work?

Broken down into these steps:

  1. Material prep (cutting and positioning)
  2. Clamp and Energize materials
  3. Cooldown

This process ranges from quick repeatable timing for thin gauge materials. And longer energized and cooldown times for thicker materials.

What is Wedge welding?

Wedge welding is the process of using a heating element positioned in an area of the machine where heat, pressure and speed are all combined to weld/seam two sheets of similar material together. It’s highly accurate, and versatile on what material types it can successfully seam. This welding process provides high quality and speed giving increased production. FLSI typically uses wedge welders in both the field and our fabrication facility.

How does Wedge welding work?

Broken down into these steps:

  1. Adjust machine settings accordingly (material type and current climate)
  2. Material prep (cutting and positioning)
  3. Clamp and engage wedge element between materials
  4. Allow machine to run entire length of weld (adjusting and re-aligning as needed)

What is Extrusion welding?

Extrusion welding is a process of plastic welding where molten plastic is pushed through a screw driven barrel and used for weld/seams, patches, repairs, beads and finishing purposes. Extruders also have a nozzle next to the extrudate tip for hot air. This hot air is used to prep the weld area to soften the material to allow for excellent adhesion of both the molten welding rod and base material sheet(s). Extruders aren’t just meant for flexible sheet welding, they’re also used in rigid plastic fabrication, plastic pipe welding as well as many other applications. FLSI utilizes different types, sizes and models of extruders as we cater to a diverse array of customers and project needs.

How does Extrusion welding work?

Broken down into these steps:

  1. Adjust machine settings accordingly (material type and current climate are major factors)
  2. Material prep (cutting, cleaning and positioning)
  3. Extrusion gun is then engaged and makes the necessary weld

What is Hot Air welding?

Hot air welding is a form of art in the industry, it requires skill, knowledge, strength and patience. It utilizes a hot air gun that blows hot air out of a narrow-wide nozzle, and a hand roller with pressure applied to the desired weld/seam area. The heat will soften the materials to weld and once the roller and pressure is applied it creates a hot air weld, sealing the seam. The Hot Air welders also come with different tips to allow for stick welding. FLSI uses many hot air welders for all of our jobs, both in the field and in the shop. It’s used mostly to seal test patches, and works on many different material types.

How does Hot Air welding work?

Broken down into these steps:

  1. Material prep (cutting, cleaning and positioning)
  2. Hot air gun tip inserted between materials
  3. Technician then begins to make pass patterns with hand roller behind the hot air gun
  4. Additional pressure and pass patterns may be needed