Which type of thermal weld is NOT commonly used for HDPE geomembranes?

The type of thermal weld that is not commonly used for HDPE (High-Density Polyethylene) geomembranes is the pressure weld. HDPE geomembranes are specifically known for their suitability for various types of thermal welding techniques, which involve using heat to bond two pieces of material together. Each welding method has its specific applications and characteristics.

Extrusion welds involve the use of a welding rod, which is melted and extruded to join two sheets of geomembrane, creating a strong bond suitable for most applications. Fusion welds use heated surfaces to melt and fuse the edges of the geomembrane together, which is effective for creating a durable seam. Hot air welds utilize directed hot air to heat the surfaces to be joined, and this method is also effective for HDPE materials.

Pressure welds, on the other hand, are not a standard practice for welding HDPE geomembranes. This method may not provide the required heat and the precise control necessary to ensure a proper bond in HDPE applications. Therefore, it is typically avoided in favor of the more effective thermal welding methods that are better aligned with the material properties of HDPE.