General Precautions:
It is recommended that Barrier systems are installed in ambient air temperatures in excess of -5oC. Ingress of water into the installation area should be prohibited. In all cases the surface onto which the Barrier is to be laid should be smooth, dry, clean and free from debris or detritus material which may cause damage to the Barrier. In all cases it is recommended the installation of Barrier geomembranes is completed by a suitably qualified and accredited installer (NVQ level 2 or equivalent). Sigma 360 Ltd can offer advice as to suitable/recommended installers. Appropriate PPE should be worn at all times during handling, placement and fixing of the Barrier. Vehicular traffic directly on top of the Barrier should be avoided. Foot traffic directly on top of the Barrier should be restricted. Where either Vehicular or Foot traffic is unavoidable, protective measures should be utilised to prevent damage to the Barrier. (Use of protection fleece and/or protection boards) Smoking, and naked flames are strictly prohibited.
Jointing and Sealing using Tapes:
A 100mm overlap print line is provided on products to assist with overlapping, jointing and sealing. For taped joints, Sigma GPS Gas Tape (50mm wide) should be utilised. The Sigma GPS Gas Tape is double sided for ease of use. To joint using tapes, ensure the first panel of Barrier is laid, and the surface is clean, dry, and free from dust. Begin by peeling one side of the protective coating from the tape, applying the tape along the outside edge of the 100mm guide line; such that the tape is between 100mm and 150mm from the Barrier roll edge. Unroll the second layer of Barrier ensuring a 150mm overlap, slowly removing the upper layer of protective film from the Sigma GPS Gas Tape, and pressing firmly on the taped joint with a silicone roller to remove trapped air. (note – taped joints have the highest failure rate when tested to ASTM D4437-08:2013 – therefore it is imperative that pressure sealing with silicone roller is implemented). Optional: Finish the joint by application of appropriate sealing tape over the joint to provide a smooth finish.
Jointing and Sealing using welding:
Before welding work is carried out trials must be completed to determine the operating window for the welding equipment and materials. It is noted that ambient air temperature, power supply and the condition of welding equipment can affect the working window. Welding window for Sigma GPS Total Gas Barrier and Sigma GPS GP2 gas barriers is 180-240 oC at a suggested rate of 1.5mm/min on low air flow. Sigma 360 Ltd recommends that any heat welding is carried out by a Construction Skills NVQ Level 2 qualified installer (or equivalent).The membranes should be overlapped by at least 100mm and care should be taken to ensure a seal between the joint. The printed 100mm overlap line should be used as a guide to ensure suitable jointing. A minimum welded overlap joint of 30 - 50mm wide should be achieved – it should be noted that the suitability of the welded joint is defined by the joint integrity, as tested in accordance with C735 (most commonly air lance – ASTM D4437-08:2013), if a welded joint passes integrity testing, it would be deemed acceptable.
Repairing Punctures:
Should tears, or punctures occur in the membrane, these can be patched using a piece of the same material sized to overlap at least 150mm beyond the extent of the puncture/tear, the lap being bonded with Sigma GPS Gas Tape in accordance with the instructions above and sealed with sealing tape, or welded to provide a continuous sheet.
