An Overview Of The CIPP Pipe Lining Process
What Is CIPP Lining? Cured-In-Place Pipe Explained for Delaware County Homeowners
CIPP lining — cured-in-place pipe — is a trenchless method of rehabilitating a damaged sewer lateral without excavating the pipe. A resin-saturated liner is inserted into the cracked or root-invaded pipe and then cured with heat, steam, or UV light to form a rigid new pipe inside the old one. The host pipe — clay tile in most Delaware County homes built before 1960 — stays in the ground; the liner carries the structural function going forward. No trench, no lawn damage, no lost landscaping.
CIPP installation is the most common residential sewer repair we perform in Delaware County. The county built out rapidly between 1920 and 1965, and that era of construction used clay tile sewer laterals with mortar joints. Those joints have been deteriorating for decades, and they are exactly where CIPP lining restores the pipe without replacing it.
The CIPP Installation Process, Step by Step
Step 1: Camera Inspection
Every CIPP job begins with a push-camera run through the lateral. The camera establishes pipe diameter, identifies root intrusion, cracked joints, offset sections, and any portion too severely damaged to accept a liner. Not every pipe qualifies — a crushed or missing section requires excavation or pipe bursting instead of lining. The camera determines which path is appropriate before any equipment is ordered.
Step 2: Hydro-Jetting
The pipe must be clean before the liner goes in. We use high-pressure hydro-jetting to clear roots, grease, sediment, and debris from the pipe walls. A second camera pass confirms the pipe is clean enough for full liner contact. This step is not optional — a liner installed into a dirty pipe will not seat correctly and will not achieve rated service life.
Step 3: Liner Sizing and Preparation
The liner is a fiberglass or felt tube saturated with a thermosetting or UV-curable resin. Wall thickness is specified based on pipe diameter, host pipe condition, and the structural load requirements of the installation. For the 4-to-6-inch laterals typical in Delaware County residential properties, thickness selection follows the design standards in ASTM F2561.
Step 4: Liner Installation
The saturated liner is inverted into position using water pressure or air, pushing the liner outward against the pipe walls. Full contact between the liner and the host pipe must be maintained throughout the entire run. Any section that fails to seat is flagged during the post-cure camera inspection.
Step 5: Curing
The resin cures by heat — steam or hot-water circulation — ambient temperature, or UV light, depending on liner type and site conditions. Heat curing is standard for residential laterals. A properly cured liner is rigid and structural, not flexible, and adheres to the host pipe interior for the life of the installation.
Step 6: Final Inspection and Lateral Reconnection
After curing, we run a final camera to confirm the liner is continuous, seated correctly, and free of voids or wrinkles. Any branch-line connections that were sealed over during installation are reopened with a robotic cutter from inside the pipe.
CIPP Liner Testing: What the Lab Actually Measures
CIPP liner testing is the quality verification process confirming that a cured liner meets the structural specifications required for long-term sewer rehabilitation. Testing occurs at two stages: the manufacturer tests liner material samples before products ship, and field quality control verifies the installed liner meets design requirements on site.
The two ASTM standards governing residential lateral CIPP work are ASTM F1216 (pressure-pipe applications) and ASTM F2561 (cured-in-place rehabilitation of non-pressure drainage conduits). ASTM F2561 is the standard directly applicable to residential sewer laterals in Delaware County. A CIPP liner testing laboratory evaluates cured liner samples against these standards by measuring three primary properties:
- Wall thickness. The liner must meet the minimum thickness specified in the design — thinner than designed means lower structural capacity. Wall thickness is measured at multiple points on each sample.
- Flexural strength. Measured per ASTM D790, flexural strength is the force required to break the liner sample under a three-point bending test. This confirms the cured liner can carry the soil and traffic loads above the pipe without cracking.
- Flexural modulus. Also measured per ASTM D790, flexural modulus (also called bending modulus) is the stiffness of the liner — its resistance to deflection under load. A higher modulus means less deformation under long-term soil pressure. Minimum modulus values are specified in ASTM F2561 based on pipe diameter and liner design.
Some laboratories also test liner samples wet — soaking the specimen in water before testing — to verify that the cured resin does not lose significant structural properties when exposed to continuous groundwater contact. The wet-to-dry property ratio is specified in ASTM F2561 for certain liner categories.
CIPP Resin Testing: What It Verifies and Why It Matters
CIPP resin testing verifies that the resin used in the liner has cured fully and reached the specified mechanical properties. An incompletely cured liner will not achieve rated structural strength and may leach unreacted resin compounds into the surrounding soil and groundwater — a materials handling and environmental issue that reputable manufacturers and installers take seriously.
The most common thermosetting resins used in CIPP lateral lining are unsaturated polyester and vinyl ester. Vinyl ester resins offer higher chemical resistance and are preferred for applications where the liner will be exposed to industrial wastewater or aggressive soil chemistry. Polyester resins are cost-effective and appropriate for standard residential sanitary sewer applications. Resin testing determines whether the cured product has achieved the minimum mechanical properties specified for that formulation.
What to ask a CIPP contractor about their liner:
- What liner product and manufacturer are you using?
- What ASTM standard has this liner been tested and certified against?
- Can you provide a certificate of compliance showing the test results for the liner material?
- Will you provide a post-cure camera inspection with footage I can keep?
A reputable installer has this information on hand before the job begins, not after. The certificate of compliance from the liner manufacturer documents the wall thickness, flexural strength, and flexural modulus from the production batch testing, and confirms the product meets ASTM F2561 minimums.
CIPP vs. Pipe Bursting: Which One Applies?
Both CIPP and pipe bursting are trenchless sewer repair methods, but they apply to different conditions. CIPP installs a liner inside the existing pipe and requires the host pipe to be structurally intact enough to hold the liner in position. Pipe bursting pulls a new pipe through the old lateral while fracturing it outward — used when the pipe is too collapsed or misaligned to serve as a CIPP host. The camera inspection determines which method is appropriate; a contractor who recommends one without a camera first is guessing.
UV CIPP Lining
UV CIPP is a variant of cured-in-place pipe lining that uses ultraviolet light rather than heat or steam to cure the resin. The liner is pre-saturated with a UV-sensitive resin and pulled into position rather than inverted under water pressure. A horizontal UV light train drawn through the installed liner at a controlled speed cures the resin as it passes. Cure times are faster than thermal methods: a typical residential lateral reaches full cure in 20 to 40 minutes after the light train completes its run.
UV CIPP liners meet the same structural requirements as thermally cured liners. Flexural modulus and wall thickness requirements under ASTM F2561 apply equally to UV-cured installations. The camera at the front of the UV light train provides real-time inspection during the cure cycle, which is a meaningful quality-control advantage over thermal curing, where liner condition can only be confirmed by a separate post-cure camera run.
CIPP Lining for Storm Sewers and Municipal Drain Lines
CIPP lining is used in storm sewer rehabilitation as well as sanitary sewer laterals. Storm sewer CIPP involves the same basic process — liner installation, curing, camera verification — but design standards differ because storm drain lines are typically larger-diameter, are not under continuous hydraulic pressure, and carry stormwater rather than sewage. ASTM F1216 and F1743 cover larger-diameter pressure and non-pressure pipe lining applications.
In Delaware County, storm drains and municipal inlet lines have been rehabilitated using CIPP methods as an alternative to full pipe replacement. Residential homeowners asking about storm sewer CIPP are usually dealing with a private yard drain or downspout drain connection that runs under the property. These are private structures, and their rehabilitation follows the same process as a sanitary lateral.
Frequently Asked Questions
Does CIPP lining work on clay tile pipe?
Yes — clay tile is the most common CIPP host pipe in Delaware County. The liner bonds to the clay interior and seals the mortar joints permanently. As long as the pipe walls are intact enough to hold the liner in place, clay tile is an excellent candidate.
What does a CIPP liner testing lab actually test?
A CIPP liner testing lab tests cured liner samples for wall thickness, flexural strength (ASTM D790), and flexural modulus (ASTM D790). These values are compared against the design minimums in ASTM F2561. Some labs also run wet specimens — soaking the sample before testing — to confirm properties are maintained under sustained water exposure. Ask any CIPP installer for the certificate of compliance showing the production batch test results for the specific liner product being installed.
What is the difference between CIPP resin testing and liner testing?
Resin testing verifies that the base resin material has achieved its specified cure and mechanical properties after the curing process — it confirms the chemical transformation from liquid resin to rigid thermoset is complete. Liner testing measures the structural properties of the finished composite (felt or fiberglass tube plus cured resin) as an assembly, using the flexural strength and modulus tests in ASTM D790. Both are part of the full quality verification picture for a correctly installed CIPP liner.
Can CIPP cover only a short section of the pipe?
Yes. Spot lining installs a short liner segment over a specific crack, root entry point, or offset joint when the rest of the lateral is in acceptable condition. Spot liners are sized to the specific defect and do not run the full length of the pipe. A full-length camera run identifies whether a spot liner is appropriate or whether the full lateral needs to be lined.
Schedule a CIPP Evaluation in Delaware County
If a camera inspection has shown root intrusion, cracked joints, or infiltration in your lateral, CIPP lining is likely the right repair. Call Advanced Drains & Underground Solutions at 1-855-DONT-DIG (1-855-366-8344) to schedule an inspection and lining assessment. We serve all of Delaware County and the surrounding Main Line communities in Montgomery County, PA.