CIPP_Patent_4135958_WoodsTrenchless Piping Installation & Repair Methods

  • TRENCHLESS PIPE REPAIRS - CONTENTS: methods for repairing existing pipes or installing new pipes without excavation; definition of CIPP cured in place pipe used for pipeline rehabilitation, a description of the CIPP repair method, where, why & how it is used. Where to obtain CIPP services & products, studies of its effectiveness.
  • POST a QUESTION or READ FAQs about CIPP and other trenchless piping installation & repair methods
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CIPP cured in place pipe re-lining repairs:

This article describes & defines CIPP, or cured in place pipe relining: a pipe rehabilitation method used to rehabilitate and thus extend the life of sewer piping, storm drains and also water and gas and process piping. We also define & describe directional drilling or horizontal drilling and we list & describe alternatives to the CIPP method including close-fit pipe, shotcrete, sliplining, and spiral wound pipe for trenchless pipe installation or repair.

CIPP can particularly extend the service life of piping abrasive applications are involved but it is also used in ordinary drain waste piping in sizes ranging from residential sewer lines to municipal and commercial piping. The page top sketch of cured in place piping installation details is adapted from Woods' 1979 US. Patent No. 4135958, "Method of lining a passageway with a resin absorbent tube"

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Trenchless Pipe Repair Methods

CIPP_Patent_4778553-3_Woods patent on trenchless pipe re lining or repairArticle Contents:

CIPP, cured in place pipe re-lining, trenchless pipe repair or replacement, close-fit, shotcrete, sliplining & other methods are discussed here.

[Click to enlarge any image]

Closefit Pipe Relining Methods

"Closefit" pipe relining refers to inserting a liner into an existing pipeline by deforming and then forcing a liner through the existing pipe.

The new pipe liner may be "structural" - able to withstand external soil and other pressures or forces - or "non-structural" - a liner is inserted inside the pipe to seal it against leakage, but the original pipe is required to withstand external forces.

In some applications the plastic liner used in closefit pipe repairs has been folded into itself to present a smaller external diameter. After the closefit pipe has been inserted through the original pipeline it is un-folded or expande.

After the liner has been inserted the original pipe deformation is reduced, allowing the original pipe to "closely fit" around the new liner, or in an opposite approach, a pipe liner that has been temporarily reduced in diameter is expanded to closely fit into the original pipeline.

An important difference between close-fit pipe relining and sliplining discussed below is that the close fit approach results in a larger diameter pipe at the end of the process than that achieved by routing a slipliner throrough the original pipe.

CIPP: Cured In Place Pipe - pipeline rehabilitation Method

According to the International Society for Trenchless Technology

Cured in Place pipe (CIPP) can be used to rehabilitate sanitary sewers, storm drains and pressure pipelines for water, gas and process effluents. Circular pipe from 100-2,700mm and a variety of noncircular pipe such as egg shapes, ovoids, and box culverts can be lined.

Lining with CIPP removes the pipe from service for the duration of the installation and reinstatement process so overpumping or provision of an alternate source of supply may be necessary. - ISTT 2014

In turn, "trenchless technology" refers to a panoply of solutions to underground piping or related systems that address repair or installation without having to excavate. Details of how CIPP may be used to re-line existing pipe systems are illustrated from several U.S. patents shown throughout this article. At left is a CIPP detail from Woods' U.S. Patent 4,778,553 from 1988.

The scope of trenchless technology ranges from directional drilling or "horizontal drilling" & boring tools used by your local plumber to route a supply, drain, or other pipe underneath portions of a building, slab, or foundation to large scale municipal sewer line or water supply piping relining such as projects described by ISTT.

Besides CIPP for existing pipeline repairs or relining and horizontal drilling cited above there is a variety of methods including inserting close-fit pipe into an existing pipeline, using shotcrete to reline pipes, sliplining an existing line, and spiral wound pipe.

CIPP or cured in place piping uses a re-lining method typically applied to existing pipelines.

Insta Pipe reliner fabric - The existing and presumably leaky or soon-to-leak pipeline is cleaned of debris and any connections that intrude into the pipeline must be removed (which means some excavation may be required).

A liner material of synthetic fabric (non-woven polyester or fiberglass) is impregnated with resin (think slow-curing epoxy) and is forced into the pipeline, then expanded by air or water pressure.

Illustrated at left is a reinforced synthetic fabric pipe liner used by Insta-Pipe, Tumwater WA, USA.

When the CIPP liner is in place, curing time is reduced by circulating hot water through the piping or by pulling a UV light through the pipe. Curing time ranges from an hour to 30 hours.

It should be no surprise that CIPP is described by ISTT, the International Society for Trenchless Technology, as CIPP was first implemented in London in 1971. CIPP was patented by Eric Wood in the U.S. in 1977 and entered the public domain in 1994. Mr. Wood holds a number of related patents - see - Wikipedia retrieved 2/20/2014. Wood's patent describes the procedure as follows:

The invention provides a method of applying a resin impregnated lining sleeve to a length of passageway surface wherein the sleeve first of all has a carrier tube everted into the sleeve from one end and out of the other end, the carrier tube is re-inverted to draw the sleeve into the carrier tube and then the assembly of carrier tube and sleeve is positioned in relation to the passageway length to be lined and the carrier tube re-everted to position the sleeve on the surface in the required position. The resin is subsequently cured and the carrier tube removed leaving a hard tubular lining shell on the passageway surface. - U.S. Patent No. US4778553 A 1988, Eric Wood

Trenchless pipe relining detail, Polivka patent 1999Related inventions and patents related to CIPP include work and patents by Guilio Catallo, Hermann Suerbaum (Method of softlining sewer rehabilitation US 5280811 A), Richard Carl Polivka, David K. York, (Method for lining of lateral pipelines with flow-through apparatus US 6001212 A), and others. Quoting from Polivka we and noting their patent illustration (left) adds this interesting detail:

An apparatus for the installation of an inverted resin impregnated flexible tubular liner in a lateral passageway from a main passageway while permitting the flow of fluids through the main passageway during the installation process is provided.

A cylindrical body with an opening to coincide with and interact with the lateral passageway has an expandable bladder on its outside with an opening coincident with the body opening and an elbow portion on the inside which is firmly attached at the opening.

An air supply inflates the bladder. A tubular elbow is attached to a flexible hose at its proximal end, the hose having a gland for injecting fluid into the hose for inverting and curing the liner. - Richard Carl Polivka, David K. York, (Method for lining of lateral pipelines with flow-through apparatus US 6001212 A), 1999

Directional Drilling for trenchless new pipe installation

Directional drilling, also referred to as horizontal drilling or lateral drilling, is used to install underground piping by drilling a pilot hole followed by a drilling system that inserts or creates an underground pipe in the drill opening.

Orignated in the oil and gas industry as a method for drilling oil and gas wells these methods have also been adapted for smaller scale residential and commercial applications of more modest needs like getting a pipe under a sidewalk or beneath a building foundation without having to excavate and destroy part of the building to run the pipeline.

Openings and ultimately the pipe diameter used for building and mechanical-system related directional drilling applications such as water piping or sewer piping can reach from seven to a thousand feet and can insert pipes ranging in diameter from 1.5 to 8.5 inches.

Small lateral drilling tool & bit (C) InspectApedia

Above is a simple dry-core drill used for short horizontal drilling applications.

Shotcrete Relining Method for large diameter drain systems

The shotcrete method of pipe relining is used on large diameter systems such as storm drains. A layer of concrete is formed by spraying wet or dry concrete against the interior of the piping or storm rain system. The shotcrete application method is also properly called pneumatically-applied concrete. Describe by industry expert, Shotcrete describes their process as follows:

We successfully and efficiently re-line corrugated steel drain pipes to extend their life. By filling in the missing and damaged sections of the invert and lining the pipe with a 1 inch thick high strength shotcrete, soil erosion beneath the culvert and road is prevented and the life expectancy of the pipe and the roadway is extended. This is the fastest, most effective, non-disruptive method to repair failing storm drains or to extend the life of newer ones. The pipe is usable 24 hours after lining.

Using a remote controlled track robot mounted with CCTV cameras and a rotary applicator allows us to bring the concrete hose and application equipment to the point of placement eliminating the need for confined space entry and all the restrictions and safety issues related to it.

The proprietary mix that we use allows this high strength shotcrete to develop a compressive strength of 6000+ PSI in 7 days. Engineering studies have indicated a 1-inch thick lining of this material on the inside of the pipe will improve the load carrying capability to H80.
- Shotcrete (2014),

Wikipedia points out that

Gunite was, at one time, a trademarked name that specifically refers to the dry-mix shotcrete process. In the dry-mix process, the dry sand and cement mixture is blown through a hose using compressed air, with water being injected at the nozzle to hydrate the mixture, immediately before it is discharged onto the receiving surface. ... The concrete mixture is by pneumatic pressure from a gun, hence "gun"-ite.

The term "Gunite" became the registered trademark of Allentown Equipment, the oldest manufacturer of gunite equipment. Other manufacturers were thus compelled to use other terminology to describe the process such as shotcrete, pneumatic concrete, guncrete, etc. - Wikipedia entry on Shotcrete, retrievef 2/20/2014, original source:

Spiral Wound Pipe Repair Method

The spiral wound pipe repair method was developed to address pipe repairs on existing piping systems whose diameter was either too small or too large for the CIPP or similar pipe relining methods discussed here.

A winding machine produces a new pipe from a plastic strip by either pushing or pulling the growing spiral-wound pipe through the water or sewage infrastructure being rehabilitated. - Formadrain (2014) -

Formadrain asserts that this approach produces a minimum reduction in the diameter of the original pipe. In Australia spiral wound pipe repair equipment is provided by Kembla Waterch. The company's product line includes spiral reliner products that can handle diameters from 225mm to 2.5m. Kembla describes the spiral wound pipe re-lining process in this detail:

Kembla’s spiral wound pipe slip lining (SWP SL) system comprises a method whereby a pipe or liner is formed in-situ by spirally winding a PVC profile strip into a host pipe normally from an existing manhole.

A major advantage of this system is that because there is a hollow opening along the entire length of spiral wound pipe at all times then sewer over pumping is not normally required and emergency flow situations can be accommodated by simply stopping work and allowing the flow to discharge through the opening in both the winding machine and the SWP SL pipe.

The T-Ribbed PVC profile strip is brought to site on a large spool. The special winding machine is set up in the base of the access chamber or pit in line with the existing pipe.  The winding machine can be dismantled into components and re-assembled in the chamber if the opening is too small. The plastic strip is fed down into the machine which spirally winds it into the required diameter.

As the spiral wound pipe exits the machine it is propelled into and along the existing pipe. The process continues until the other access is reached. The small annulus space between the SWP SL pipe and the existing sewer is then grouted to complete the installation. - Kembla Watertech (2014)

Split & Reline Existing Piping

A different approach to trenchless pipe repair for existing pipelines inserts equipment to split an existing pipe, permitting a replacement liner to be drawn through the original pipe opening. Below is Spartan Tool's Trenchless Pipe Replacement equipment.

Spartan Tools' Trenchless Pipe Replacement Tool, According to the company,

This trenchless pipe repair and replacement system allows 2"-6" pipe replacement with up to three 45-degree bends in the pipe and can even upsize from 4" to 6" pipes. ... Spartan Tool’s Water Line Slitters make quick work of one of your most common jobs – replacement of old and failed water lines. 

Simply feed the included cable through the existing water line, attach a replacement line to trailing “carrot”, and tug the slitting head through the line, replacing it seamlessly in the same location as the original line.  Very little digging, no trenching, and in a matter of minutes you’re ready to hook up the new service!- 2014

Directional or horizontal drilling will be used where there is not an existing pipeline and has its origins in the oil and gas industries where very large distances are drilled for those purposes.

But in infrastructure piping systems such as installing a pipe below an existing building foundation, slab, or a sidewalk, similar if more modest methods and equipment accomplish a similar function

Sliplining Pipe Repair Method Description

The sliplining approach to repair of existing pipelines uses a liner that is drawn or inserted through the original pipeline. The slip-liner must be of smaller diameter than the pipe it is to line, leaving adequate space inside the original pipe to insert the new liner. Hobas, an industry expert describes the process:

During installation, the pipes are pushed or pulled into the existing pipeline and the remaining annular space between the host and liner pipes is filled with pressure resistant grouting, usually a mixture of binding materials. This fixes the inserted pipe in position, creating a pipeline of the same integrity as a new one.

The relining process involves pushing or pulling the new pipes into the existing pipeline and filling the remaining annular space between the host and liner pipes with pressure-resistant grouting, usually a mixture of binding materials. This fixes the inserted pipe in position, making it fit to take over the complete structural load capacity. HOBAS Relining Pipes are particularly suitable for pipe rehabilitation, as they are of low weight, corrosion resistant, quality assured, easy to install and resist the load from the grouting. - Hobas (2014)

Resources for Trenchless Pipe Repair: methods, equipment sources

In addition to citations at REFERENCES see

Trenchless Pipe Residential Applications Q&A

Reader Question 2/19/2014 teri  said:

Almost 2 years ago i had the drain line below my bathroom lined with CIPP. ever since that time i have had a moisture problem in my bathroom. after showering in the morning, i hang my towel on the rack, come home after working 8 hours and the towel is still damp. my toilet tissue is always 'damp' feeling and lots and lots of mildew, which i never had prior. there is no exhaust fan, but there never has been, there is a window and this house was built in 1950. could it be possible, when the plumber performed the CIPP that he blocked off the vent pipe that leads from the sewer line thru the roof? my paint is peeling off my walls in the bathroom on the wall that the shower toilet and sink are on. help please !

Reply: Teri, the CIPP that I know about is described by ISTT as: CIPP Lining

Cured in Place pipe (CIPP) can be used to rehabilitate sanitary sewers, storm drains and pressure pipelines for water, gas and process effluents. Circular pipe from 100-2,700mm and a variety of noncircular pipe such as egg shapes, ovoids, and box culverts can be lined. Lining with CIPP removes the pipe from service for the duration of the installation and reinstatement process so overpumping or provision of an alternate source of supply may be necessary.

From your note I understand that you had some sort of drain treatment like this. We're talking about fixing a plumbing drain, presumably to stop it from leaking. By no means would stopping a drain leak explain an excessive bathroom moisture problem. On the contrary that ought to reduce bath moisture if in the process we stopped leaks from leaving water under the building.

The only relationship between a CIPP drain line repair and increased bath moisture that occurs to me is listed as item 4 in my notes below:

Here are some things to check:

1. How is the bathroom ventilated? As there is no working exhaust fan, only ventilation by opening a window can reduce moisture and the effectiveness of that approach varies by season and window use and the ability of air to enter and exit the bathroom.

2. Is the bathroom window (which permits omission of an exhaust fan in some jurisdictions) actually operable, and if so is it opened to ventilate the bathroom? When, for how long=?

3. Had the use of the bathroom changed in some way: long hot showers?

4. Did the CIPP installation (or some other event) damage or block or disconnect the vent piping system? A clogged vent or a vent that leaks could cause poor drain performance (you'd hear gurgling for example) and a disconnected vent could vent moisture into the building floor or walls depending on where the opening occurs.

More about the diagnosis and cure of indoor moisture problems is at MOISTURE PROBLEMS: CAUSE & CURE.

Epoxy for Leaky or Lead Pipe Re-conditioning & Re-Lining Options

Lead water pipe (C) Daniel Friedman

Reader comment: Ace DuraFlow ePipe® Restoration Services for deteriorated or clogged piping

2016/03/21 Bill said:

Have you become familiar with Ace Duraflo's EPipe solution? I encourage you to check it out as it is a much more cost effective way of dealing with both residential lead issues and pin hole leaks. You will also discover they are doing considerable relining of lead service pipes in the UK.

This comment appeared originally at LEAD PIPES in BUILDINGS


Ace DuraFlow EPipe is a procedure using a combination of heating, drying and cleaning (sanding) the interior of deteriorated piping followed by installation of an epoxy liner inside the pipe. The system is used in the North America, U.K., and other countries. The company's website does not (that I could find) provide much detail, cost comparisons, research or much technical information but the procedure indeed may be suitable for some piping problems depending on the pipe condition. The company notes that their process is suitable for domestic water systems (galvanized, copper, and PEX piping) and non-potable systems.

The company provides a web pages listing plumbing code and other approvals for their epoxy pipe re-lining procedure for the U.S., Canada, Latin America, the U.K., the E.U., and other countries.

Research about the long term potability of water flowing through epoxy-lined piping may bear a look.

Also see


Continue reading DRAIN & SEWER PIPING or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see TRENCHLESS SEWER REPLACEMENT for a discussion of using trenchless pipe technology for replacing failed septic drainfield piping

Or see RADIANT SLAB TUBING LEAKS where we discuss epoxy pipe lining repairs


Suggested citation for this web page

CIPP PIPE LINING REPAIRS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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