What Is Trenchless Drain Lining? A New Pipe Inside the Old One

English transcript

Transcript from the published G02 explainer script. Product figures are published specifications, not project-specific design values; confirm the formulation and installation conditions with Reliance.

A cracked drain under the driveway. The usual fix is a trench. Drain lining skips the trench. It goes in through an existing access point, and builds a new pipe inside the old one. Old drains fail in a few familiar ways: cracks, open joints, and roots growing in. Lining fixes them in one pass. A flexible tube, soaked in resin, goes in through the access point. Air or water pressure turns the tube inside out as it travels, and presses it onto the wall. Then the resin cures in place. What's left is a new, jointless pipe, inside the old one. That's full-length lining: the whole run, from one access point to the next. It's the right call when the damage runs along the pipe. But often, the camera survey finds one defect on an otherwise sound pipe. Then you line only that point, with a sectional patch. A repair packer carries it in, inflates, and holds it on the wall while it cures. The packer comes out. The patch stays. Either way, the strength comes from glass fibre. This E M K six-hundred four-fifty cloth stitches a woven roving to a chopped-strand layer. A liner is a composite. The fibres carry the load; the resin locks them together and seals. The two resin components are mixed at one to two. The cloth takes one and a half to two kilograms of resin per square metre, and is folded to at least three layers. Three layers of this cloth put about three point two kilograms of glass into every square metre of wall. Cured, the published values are a bending strength of one hundred and forty-two megapascals, a compressive strength of one hundred and sixty-four, and a flexural modulus of nine thousand two hundred and fifteen. Temperature sets the clock. Forty minutes to cure in summer, sixty in spring, ninety in winter. Building drains have bends. A long lateral packer for DN50 to 100 is only forty-eight millimetres across, and flexes with the pipe. It inflates right through a swept bend, and presses the patch onto the crack. A full-length liner has one more weak point: its ends. Water can track along the gap between the liner and the old pipe. An end seal closes it: an E P D M rubber sleeve, pressed onto the wall by stainless steel bands. Two stainless expansion bands come as standard. Sleeves come in widths of two-seventy, three-fifty and five hundred millimetres, from DN200 to 3000. So which one? Say the camera finds one cracked joint, and the rest of the pipe is sound. Digging it up is the slowest route. A full-length liner would line pipe that isn't broken. A sectional patch fixes the point. If the cracks run the whole length, the answer flips: line the run. Before you order packers or lining materials, prepare four things. The measured inner diameter, and the pipe material. Where each defect is, and how long, from the CCTV survey. The bends between the access point and the defect. And the pipe temperature, which sets the cure time. One limit: a collapsed or sagging pipe can't be lined. It has to be dug. Send us your pipe size, material and CCTV findings, and we'll match the packer and the lining materials.