PVC panels arrive at the site and are deployed according to a panel layout diagram for that project. Panels are overlapped depending upon the project for field welding. There are three primary methods of field seaming PVC Geomembrane panels:
1. Adhesive Seaming
Adhesive seaming of PVC is the oldest and simplest method of sealing Geomembrane panels. The process involves coating each surface of the panels to be joined with a bodied solvent adhesive. The coated pieces are then placed together and pressure is applied by a roller or other device to mate the pieces together and create a bond.
2. Chemical Fusion Seaming
Chemical fusion welding utilizes a chemical fusion agent (solvent) to dissolve the surfaces of the pieces of material to be joined. The chemical fusion agent is introduced between the two sheets of PVC to be welded, and while the surface of the material is molten, pressure is applied to mate the two surfaces together. This provides a homogeneous bond between the two sheets after the fusion agent evaporates. This method is used extensively in the fabrication and installation of PVC Geomembrane.
3. Thermal Fusion Welding
Thermal fusion welding of PVC has been used in Europe for many years. Its use for the field welding of PVC Geomembrane in the United States began around 1990. Thermal fusion welders consist of a hot wedge or hot air device that heats the surface of the material to a molten state, while traveling along the length of the seam. Pressure rollers follow the heating device to press the two pieces of PVC Geomembrane together while the surfaces of each sheet are melted. This provides a homogeneous bond between the two pieces.