When it comes to seaming HDPE, a specialized approach is employed to ensure its durability and integrity. HDPE is designed to be thermally welded, demanding precision and expertise. As such, only a technician with the requisite training is authorized to perform this thermal welding, ensuring the highest quality and effectiveness of the seam.
How is HDPE INSTALLATION?
Installation of Geomembrane products Cut&Weld INTRODUCTION
This manual provides an overview of the INNO group Installation method with industry accepted practices to ensure that the INNO's geomembrane products installed will best perform for their intended purpose. All installation work will be performed in strict accordance per the customer's specifications.
1:HDPE and LLDPE Geomembrane Quality Control
INNO Group installs HDPE (High Density Polyethylene) and LLDPE (Linear Low Density Polyethylene) geomembranes.
2. Delivery, Storage and Handling
2.1 Prior to unloading, the handling equipment is inspected to verify that it will not damage the material. Fabric straps or other approved apparatus are used for handling of material.
2.2 Rolls must be examined upon unloading to insure that there is no damage to the material and to assure that the correct material for the job has been received.
2.3 The storage area must be secure to prevent vandalism and thefts and must be such that rolls are not likely to be damaged by passing vehicles. The storage area shall be such that continuous contact with water is minimized. The storage area shall be smooth, flat and free of rocks or other objects that could cut or puncture the liner. Rolls of geomembrane do not need protection from normal weather conditions.
3.Preparation for Seaming
3.1The surface of the geomembrane shall be wiped with a clean cloth to remove moisture, dust, dirt, debris, or other foreign material. Solvents or adhesives shall not be used. Panels shall overlap by a minimum of three inches for all welds.
3.2 Fish mouths or wrinkles at seam overlaps shall be cut to achieve a flat overlap. The cut fish mouths or wrinkles shall be
welded where the overlap is more than three (3) inches. When there is less than three inches overlap, an oval or round patch extending a minimum of three inches beyond the cut in each direction shall be used.
3.3 Seams shall be welded only when ambient temperature is between 32°F and 110°F as measured six inches above the geomembrane surface unless other limits are approved, in writing, by the Engineer (see Section G for site-specific requirements, if any). For temperatures below 32°F, the following procedures shall be utilized:
3.4 When the weather is clear and sunny with gentle winds (10 mph or less) wedge welding can normally be performed at an ambient temperature between 15°F and 32°F (liner temperature is usually warmer than ambient due to the sun) without additional provisions other than adjusting the welding machine. Welding temperatures and machine speeds are adjusted to compensate for cloudy weather and higher winds.
3.5 For temperatures between 5°F and 15°F some means of preheating the liner other than that provided by the welding machine is needed. Types of preheating (space heaters, temporary shelters and combinations of the two) will be determined by the individual job conditions.
3.6 The following variables are measured and recorded:
*Liner Temperature (surface contact thermometer)
* Ambient Temperature (6" above liner)
*Wedge Temperature During Welding
* Wedge Speed
* Temperature Set Point of Wedge3.7 The wedge temperature during welding must be monitored by the machine operator to insure temperature consistency.
10.4.5 No welding can take place when it is snowing, sleeting, or raining. Snow and ice must be removed from the liner prior to welding. Snow removal from the site area is the responsibility of the owner or contractor.
3.8 Trial Welds: Trial welds shall be performed on geomembrane samples to verify welding equipment operations and performance of seaming methods and conditions. Minimum of two trial welds per day or shift per welding apparatus will be made, one made prior to the start of work and one completed mid shift. Additional trial welds shall be made as necessary when air temperature changes by more than 10°F or winds change by more than 8 mph or in accordance with site-specific requirements, if any (see Section G). Welds shall be made under the same surface and environmental conditions as the production welds (i.e., in contact with geomembrane subsurface and similar ambient temperature).
3.9 Trial Weld Testing: Samples shall be at least five feet long and one foot wide with the seam centered lengthwise. Five, one inch wide tests strips shall be cut from the trial weld. Each of the specimens shall be tested in the field for peel. A trial
weld specimen is considered to pass when the peel test results meet or exceed the project specifications.
For double-wedge welding, both welds shall be individually tested and both shall be required to pass in peel. The trial seam tests must pass before welding on the geomembrane is started. Remaining samples shall be retained for future testing.
4.0 The primary method of welding shall be wedge welding and extrusion welding. Hot air seaming shall be used for repairs and detailing.
4. Welding Procedures
4.1 Fusion (Wedge) Welding:
Fusion (wedge) welding utilizes a metallic wedge heated to the required temperature and guided between the lapped edges of adjacent panels. The welding machine is aligned and set to the required temperature (typically 325°to 400° Cependding on the material thickness and site conditions), and the machine travel speed is set to the required setting for the applicable material thickness. The wedge heats the area of the two panels to be joined to the required temperature.
Rollers immediately following the wedge exert the required pressure on the heated area to obtain fusion between the adjoining panels.
4.2 Welding apparatus shall be automated, vehicular-mounted, and equipped withdevices giving applicable temperatures and pressures.
4.3As the welding progresses, the welding operator takes care to assure correct machine speed and alignment.
4.4 Extrusion Welding:
Adjacent panels shall be tack bonded together using procedures that do not damage the geomembrane, allow required tests to be performed, and are not detrimental to final seaming. Welding apparatus shall be free of heat-degraded extrudate before welding. The geomembrane surface shall be abraded to a maximum ¼ inch beyond the weld bead area, using a disc grinder, or equivalent, not more than ½ hour before welding. The top edges of geomembrane 60 mil or greater shall be beveled 45° using a hand held grinder. The ends of all seams, which are more than five minutes old, shall be ground when restarting the weld. Grinding depth shall not exceed ten percent of the liner thickness.
4.5 Extrusion welding entails placing a hot extrudate on top of the preheated lap of two adjoining panels while
simultaneously applying pressure, and utilizes a welding rod made from the same type of resin as the membrane. The welding rod is melted inside the extrusion welding machine to form the hot extrudate. Preheating of the sheet in the weld area is performed by the extrusion welding machine.
4.6 The Teflon shoe (that determines the profile of the molten extrudate) is checked for correct dimensions. The
temperature controllers are then set to appropriate temperatures and the machines are allowed to heat to the machine temperature set point. When the seam area is prepared, the welding machine is positioned so the nozzle and the shoe are flat on the seam. As the machine is moved forward, care is taken to assure that the point of the preheat nozzle is centered on the edge of the top sheet and is as close to the sheet as possible.
As the welding progresses, the welding operator takes care to assure correct machine speed and alignment.
4.7 Hot Air Seaming:
Hot air seaming utilizes a resistance heater, blower and temperature controller to force hot air between the lapped edges of the adjoining geomembranes. The hot air melts the opposing sheet surfaces. Pressure is immediately applied to bond the two sheets.
4.8Hot air seaming is commonly used for repairs and detailing tasks.
5. Seam Inspection and Repair
5.1 After welding, a close visual inspection of the seam is made. This is done as soon as possible after the weld has
been completed. The inspection is to include weld alignment.
For extrusion welding, the weld thickness and profile is inspected.
5.2 Defective areas are marked and repaired then the repairs are inspected and approved. This inspection/repair
process is carried out in a systematic manner as soon as possible to ensure that no defective area goes unrepaired
Welding Accessories can be supplied free of charge after the quantity is reached