How Trenchless Pipe Repair Works: A Patch Cured in Place

English transcript

Transcript based on the published explainer script. Product specifications and selection guidance should be confirmed with Reliance.

A cracked sewer, under a busy road. The usual fix is to dig it up. This repair goes in through the manhole instead. A patch is pressed onto the crack from inside the pipe, and the road above stays open. A liquid resin, cured for about forty minutes, becomes a patch with a bending strength of one hundred and forty-two megapascals. So how does it get there? Let's follow one repair. A crack in the pipe wall lets groundwater in. Left alone, it grows. But the defect is short: one point, not the whole pipe line. So you repair the point. The patch starts as fiberglass cloth and a two-part resin. Component A and component B are mixed at one to two, and stirred for one to two minutes. The resin is spread onto the cloth, which is folded to at least three layers. The wet patch is wrapped around a repair packer, and the packer is pulled through the pipe to the crack. Then the packer is inflated. It presses the patch against the wall all the way round, squeezing out trapped air. The leak stops, and the packer holds the patch in place. Why press so hard? Pressure is force spread over area. A repair packer for a three-hundred-millimetre pipe inflates to two bar. Two bar is twenty newtons on every square centimetre of patch. That's two hundred thousand newtons on each square metre. About twenty tonnes, pushing the patch onto the wall. Smaller packers run at higher pressure: four bar on the RP 70-150. Larger ones run lower, down to one bar on the RP 1000-1500. Always inflate to the rating of your model, and read it on the gauge. Now the resin cures, while the packer holds the patch against the wall. In summer, that takes about forty minutes. Then the packer is deflated and pulled out. The cured patch stays on the wall, sealing the crack from inside. Temperature sets the clock. Forty minutes in summer, sixty in spring, ninety in winter. So plan the working window for the site temperature. This is a finished point repair, seen from inside the pipe. Cured, the published values are a bending strength of one hundred and forty-two megapascals, and a compressive strength of one hundred and sixty-four. Packers come in standard and bypass versions. A bypass packer has a channel through the middle, so the flow keeps passing while the patch cures. Standard models cover DN50 to 1500. Bypass models cover DN100 to 1500. Before you order, prepare four things. The measured inner diameter and the pipe material. The defect length, and the repair length you need. The access route: manhole, bends, and the packer's deflated size. And the flow: whether you need a bypass, and the back pressure. Send us your pipe size, material and defect length, and we'll match the packer and the repair materials.