Essential details
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Product Introduction
Geomembrane Welding
1. The welding process using a hot-wedge welder consists of the following steps: adjusting pressure, setting temperature, setting speed, inspecting the seam overlap, feeding the membrane into the machine, starting the motor, and applying pressure for welding.
2. The seam area must be free of oil stains and dust; the overlapping sections of the HDPE geomembrane must not contain trapped debris such as sand or silt. If any foreign matter is present, it must be thoroughly cleaned away prior to welding.
3. At the start of each day's welding operations, a test weld specimen (0.9 mm × 0.3 mm) must first be produced on-site. The overlap width for this specimen shall be no less than 10 cm. The specimen must then undergo on-site peel and shear tests using a tensile testing machine. Once the specimen passes these tests, formal welding may commence using the speed, pressure, and temperature settings established during the test phase. The test specimen must be clearly marked with the date, time, and ambient temperature. During the actual welding process, the operation of the hot-wedge welder must be continuously monitored, and fine adjustments to the speed and temperature should be made as necessary based on actual on-site conditions.
4. The weld seams are required to be neat and aesthetically pleasing; there must be no instances of slippage or deviation during the welding process.
5. In instances where the length of the geomembrane is insufficient and longitudinal splicing is required, the transverse seams should be completed first, followed by the longitudinal seams. Transverse seams should be spaced at least 50 cm apart and arranged in a "T" configuration; they must not form a cross-shaped intersection.
6. Adjacent geomembrane seams should be staggered whenever possible to avoid alignment. The junctions formed between membrane panels should ideally be "T"-shaped; cross-shaped intersections should be minimized. Any points where longitudinal and transverse seams intersect must be reinforced using an extrusion welder.
7. Care must be taken to avoid creating "dead folds" (permanent creases) while welding the membrane. When laying out the HDPE geomembrane, an allowance for thermal expansion and contraction—dictated by the local temperature fluctuation range and the specific performance characteristics of the HDPE material—must be reserved.
8. If the temperature gauge on a handheld welder indicates a temperature below 200°C, the welding tip must be cleaned using a clean cloth or cotton waste before resuming welding. If necessary, the tip should be reground; under no circumstances should the tip be wiped with bare hands.
9. If the seam area is compromised by condensation, moisture, sand, or other contaminants, these issues must be resolved and the area prepared appropriately before welding is attempted. 10. Welding operations must not be conducted during rainfall, or when joints are damp, covered in dew, or heavily contaminated with sand; however, exceptions may be made if appropriate protective measures are implemented.
11. When the ambient temperature falls below 5°C, construction should be suspended in accordance with standard specifications. If construction is absolutely necessary under such conditions, the welding equipment must undergo a preheating treatment prior to use.
12. During the extrusion welding process, the slider on the welding gun nozzle should be inspected frequently. If the slider shows signs of significant wear, it must be replaced immediately to prevent damage to the geomembrane surface.
13. When welding geomembranes, power should be supplied by a generator with excellent voltage stabilization capabilities. In special circumstances where local utility power is utilized, a voltage regulator must be employed.
1. The welding process using a hot-wedge welder consists of the following steps: adjusting pressure, setting temperature, setting speed, inspecting the seam overlap, feeding the membrane into the machine, starting the motor, and applying pressure for welding.
2. The seam area must be free of oil stains and dust; the overlapping sections of the HDPE geomembrane must not contain trapped debris such as sand or silt. If any foreign matter is present, it must be thoroughly cleaned away prior to welding.
3. At the start of each day's welding operations, a test weld specimen (0.9 mm × 0.3 mm) must first be produced on-site. The overlap width for this specimen shall be no less than 10 cm. The specimen must then undergo on-site peel and shear tests using a tensile testing machine. Once the specimen passes these tests, formal welding may commence using the speed, pressure, and temperature settings established during the test phase. The test specimen must be clearly marked with the date, time, and ambient temperature. During the actual welding process, the operation of the hot-wedge welder must be continuously monitored, and fine adjustments to the speed and temperature should be made as necessary based on actual on-site conditions.
4. The weld seams are required to be neat and aesthetically pleasing; there must be no instances of slippage or deviation during the welding process.
5. In instances where the length of the geomembrane is insufficient and longitudinal splicing is required, the transverse seams should be completed first, followed by the longitudinal seams. Transverse seams should be spaced at least 50 cm apart and arranged in a "T" configuration; they must not form a cross-shaped intersection.
6. Adjacent geomembrane seams should be staggered whenever possible to avoid alignment. The junctions formed between membrane panels should ideally be "T"-shaped; cross-shaped intersections should be minimized. Any points where longitudinal and transverse seams intersect must be reinforced using an extrusion welder.
7. Care must be taken to avoid creating "dead folds" (permanent creases) while welding the membrane. When laying out the HDPE geomembrane, an allowance for thermal expansion and contraction—dictated by the local temperature fluctuation range and the specific performance characteristics of the HDPE material—must be reserved.
8. If the temperature gauge on a handheld welder indicates a temperature below 200°C, the welding tip must be cleaned using a clean cloth or cotton waste before resuming welding. If necessary, the tip should be reground; under no circumstances should the tip be wiped with bare hands.
9. If the seam area is compromised by condensation, moisture, sand, or other contaminants, these issues must be resolved and the area prepared appropriately before welding is attempted. 10. Welding operations must not be conducted during rainfall, or when joints are damp, covered in dew, or heavily contaminated with sand; however, exceptions may be made if appropriate protective measures are implemented.
11. When the ambient temperature falls below 5°C, construction should be suspended in accordance with standard specifications. If construction is absolutely necessary under such conditions, the welding equipment must undergo a preheating treatment prior to use.
12. During the extrusion welding process, the slider on the welding gun nozzle should be inspected frequently. If the slider shows signs of significant wear, it must be replaced immediately to prevent damage to the geomembrane surface.
13. When welding geomembranes, power should be supplied by a generator with excellent voltage stabilization capabilities. In special circumstances where local utility power is utilized, a voltage regulator must be employed.
**Precautions**
(1) The treatment of geomembrane joints is a critical procedure in construction, directly impacting the operational lifespan of the project. Quality inspections indicate that the thermal welding method is the most ideal approach (adhesive bonding using specialized agents is also an option). The thermal welding method involves heating the contact surfaces of the PE geomembrane sheets until they melt, and then fusing them into a single, integral unit through the application of pressure.
(2) Geomembranes should be laid out in a consistent direction. A specific margin of the PE membrane (free from the non-bonding PET layer) must be reserved along both edges of each sheet. During installation, the alignment of each individual geomembrane unit must be carefully adjusted to facilitate the subsequent welding of adjacent units.
(3) Once laid out, the geomembrane sheets must be weighted down with sandbags to prevent displacement by wind. The edges and joint areas must be kept free of dirt, moisture, dust, and other contaminants.
(4) Prior to welding, the PE single-layer edges of the two adjacent sheets at the joint must be carefully aligned to ensure a proper overlap width; the overlapping surfaces must be flat and free of wrinkles.
(5) Welding operations should be performed by experienced technicians using specialized welding equipment. The temperature and welding speed settings must be carefully calibrated (adhesive bonding may also be used as an alternative).
(6) Years of practical experience have demonstrated that the geomembrane thickness should be no less than 0.25 mm; sheets that are too thin are prone to developing pinholes and are susceptible to damage during construction, thereby compromising their anti-seepage effectiveness. During geomembrane installation, particular attention must be paid to ensuring that the sheets are not laid too tightly, that no wrinkles or folds are present, and that all splices are securely bonded. Construction must strictly adhere to technical specifications, maintaining rigorous quality control across five key stages: preparation, laying, splicing, inspection, and backfilling.