Lining Clay, Cast Iron, Orangeburg, Concrete and Other Sewer Pipe

Pipe follows the age of the building

A sewer pipe lining contractor can usually guess the pipe before the camera goes in, from the year the house was built and the part of the country it is in. Before mid-century, laterals were vitrified clay and the pipe inside and under the house was cast iron. From the late 1940s into the early 1970s, millions of tract houses got Orangeburg fiber pipe because it was cheap and light. From the 1970s on, plastic took over, ABS first and then PVC. Municipal mains are a longer story: clay and brick in the 19th century, concrete and asbestos-cement through the 20th, plastic and fiberglass now. Each material fails in its own way, each needs its own cleaning, and each has a point past which it is no longer a lining candidate. This page goes through them one at a time.

Clay sewer pipe lining

Vitrified clay is fired ceramic, and it does not rust, rot or dissolve; clay sewers from the 1880s still carry flow. It fails at its joints. Clay comes in short lengths, two to five feet, joined bell-and-spigot with mortar or, later, a rubber gasket, and every joint is a place where ground movement can open a gap, a root can enter, and a section can settle or shift. The classic clay lateral on a camera is a chain of root masses at each bell, with mineral deposits where groundwater has been leaking in and perhaps an offset or two where a tree root has lifted a section. Clay also cracks longitudinally under a point load, a driveway or a root pushing from the side, while the pieces stay in place.

All of that lines well. A hydro jetter and a root cutter clear the bells to bare clay, the camera confirms the offsets are small enough to pass, and a felt-and-epoxy liner cures into a single pipe that seals every joint along its length. Roots do not return because there is no joint to return to. What rules clay out is the same thing that rules any pipe out: an offset larger than the liner can bridge, a collapse where a section has been crushed, or a belly where sections have settled. Those get a sectional point repair at the one spot and a liner through the rest, or a pipe burst if the damage is widespread. Clay is also what most municipal sanitary laterals and small mains are made of in older cities, so it is the host pipe for most municipal pipe lining programs.

Cast iron

Cast iron is the drain pipe inside and under buildings built before the 1970s, and it is still used in commercial construction. It fails by corrosion from the inside. In sanitary service, the bottom of the pipe sits in water and sewage and pits; scale, a crust of iron oxide, builds on the wall and narrows a four-inch pipe to three or two; and eventually the invert rusts through in a channel along the bottom, so that the pipe is a trough rather than a tube, and the sewage runs on the soil beneath. On a camera the sign is a rough, dark, narrowed bore with a ragged bottom edge and sometimes a view of soil.

Lining cast iron is a two-stage job. The scale has to come off first, with chain flails, carbide-tipped cutters or a descaling nozzle on a jetter, so that the liner bonds to sound metal and the bore is back to its original diameter; the camera pass after descaling is what reveals how much pipe wall is left. Then the liner goes in. Because a cured-in-place liner is designed to stand on its own, cast iron that has lost its invert for most of its length still lines, as long as the remaining pipe holds the liner round during the cure. The alternative for small-diameter cast iron with pitting but no holes is an epoxy coating, which seals and smooths but adds no strength; the sewer pipe liners page explains when each applies. Under a slab, where cast iron is most often found, the number of branch connections to reinstate afterward drives the price more than the pipe material does.

Orangeburg

Orangeburg is the trade name that stuck to bituminized fiber pipe: layers of wood pulp pressed with pitch into a pipe that was light enough for one man to carry and cheap enough to put under a subdivision. It was laid from the 1940s to the early 1970s, most heavily in postwar tracts, and it was rated for about 50 years, which means all of it is past its life now. It fails by absorbing water and softening, then deforming under soil load. The round pipe goes oval, the top flattens, the inside wall blisters and delaminates in layers that catch everything that flows past, and finally it collapses. On a camera, Orangeburg looks like a dark, fibrous tube with a flattened crown and shreds hanging from the walls.

Orangeburg can be lined while it is still round. A liner cured inside it becomes the pipe, and the fiber shell outside it no longer matters. The difficulty is that Orangeburg rarely fails in one place; a run that has gone oval in one section has usually begun to deform in others, and a liner cannot be inflated to a round pipe inside an oval host. Snaking an Orangeburg line, which is what most owners do first, chews the blistered wall and accelerates the collapse. The common outcome is that a deformed Orangeburg lateral is pipe burst, since the bursting head breaks the soft fiber apart easily and the new polyethylene pipe is pulled in behind it, and only Orangeburg caught early is lined. The pipe lining vs pipe bursting page has the comparison.

Concrete and reinforced concrete

Concrete pipe is the material of municipal sanitary and storm mains, culverts and some older laterals, in diameters from four inches to several feet. It fails three ways. Its joints open as the ground settles, letting groundwater in and sand out, which is the source of many sinkholes over a storm line. Its invert erodes under years of grit-laden flow. And in sanitary service, hydrogen sulfide gas from the sewage is converted by bacteria on the crown of the pipe into sulfuric acid, which eats the concrete from the top down until the reinforcing steel is exposed and the crown falls in. Storm pipe skips that last failure and gets the first two.

Concrete lines well because it almost always holds its shape until very late. Cured-in-place felt or glass liners handle concrete from four inches up to the limits of the inversion or UV equipment, and the liner's own wall thickness carries the load whether or not the invert is still there. Above roughly 36 inches, and in culverts and manholes, spin-cast lining, in which a rotating head sprays cementitious or geopolymer mortar onto the wall in passes, is usually the lower-cost structural repair and restores the crown that acid has removed. A concrete line that has lost its crown entirely, with the soil above visible, is beyond lining until a point repair or a short dig restores a form.

Asbestos-cement (Transite)

Asbestos-cement pipe, sold as Transite among other names, was used for water mains and sewer mains and laterals from the 1930s into the 1970s. It is cement reinforced with asbestos fiber, and it fails like concrete: open joints, cracks and a softened, eroded wall where the cement has leached out. It lines like concrete too, and lining is in fact the preferred repair, because it leaves the asbestos-cement pipe undisturbed in the ground. Cutting, breaking or bursting asbestos-cement releases fiber and is regulated; a liner cured inside it does neither, and reinstatements are cut through the liner and the pipe wall with the material wetted and the cuttings controlled. Bids on asbestos-cement should say how the reinstatement cuttings will be handled.

Corrugated metal

Galvanized or aluminized corrugated metal pipe is the storm pipe of parking lots, subdivisions and road culverts from the 1950s on, and it rusts through along the bottom where water runs until the invert is gone and the soil above washes in. It is lined constantly, in storm service, with cured-in-place liners up to a few feet and spin-cast mortar above that, as the storm drain lining page describes. The liner has to be designed for a host that contributes nothing, and the corrugations have to be accounted for in the design thickness. Metal that has lost its shape, a culvert whose crown has sagged under traffic, is a replacement or a sliplining case.

ABS and PVC plastic

Plastic pipe does not corrode, does not root at solvent-welded joints and does not deform under normal loads, so most of it has nothing wrong with it. It gets lined when something else went wrong: a section crushed during construction or by a later excavation, a joint that was dry-fitted and never glued, ABS from a bad batch that cracked along its length, or a bellied run under a slab that cannot be dug. The smooth plastic wall does not give a resin much to bond to, so epoxy liners sized for a tight mechanical fit are preferred, and the camera before and after is especially important. A plastic line with a belly is still a belly after lining, and plastic is the material most often sent to open-cut replacement because the line is usually shallow and recent enough to have little built over it.

What the camera settles

Everything above is what to expect. The camera is what decides. A camera inspection names the material, shows how it has failed, locates each defect from the surface, and tells an installer which of the fixes on this site the line needs: a liner alone, a liner with a point repair at the one bad spot, a burst through the collapsed section and a liner through the rest, or a trench. Your state guide, reached from the pipe relining near me page, covers which materials are typical where you live and whether a verified installer is listed there.

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