Intent

It is the intent of this specification to provide for installation of up to 300 feet long tubular resin impregnated sleeve, affixed to the walls in the middle of a main sewer pipe run, starting from on manhole to another manhole or to a blind outfall, upstream or downstream.

General

The method involves the impregnation of an absorbent carrier material; the inversion of the material into the pipe, the curing of the sleeve leaving behind a hard plastic sleeve mechanically bonded to the host pipe.

The carrier material

The carrier material shall be of fibrous absorbent composition tailored to achieve the following:

1. Allow the migration of resin from its internal structure by compressing to a thickness of less than 90% of its uncompressed thickness under a pressure 1 psi.

2. The material must consist of non degradable fibers such as polyester or polypropylene or corrosion resistant fiberglass.

3. The material must have an abrasion resistant, chemically resistant, fully bonded coated surface in the lateral portion to ensure that on curing a smooth surface free from blemishes, pinholes or loose non wetted fibers.

4.  Where fiberglass is used a surface veil or a layer of felt must be used to act as a barrier to prevent osmosis or wicking of the strands.

5.  The carrier material must be resistant to the resin used and must withstand any installation forces without losing its integrity.

The resin

 The resin must be a thermosetting resin cured by either heat or chemically via the use of accelerators, or any other safe energy source which does not involve the use of electrical current within the main sewer, unless where evidence can be supplied of the intrinsic safety.

 The resin must give sufficient working time above ground to enable impregnation of the fabric, but must cure to sufficient hardness to carry overburden loads within a maximum of 8 hours from time of insertion inside the pipe.

 Testing

 Visual Inspection

 On completion of the work a CCTV survey should be carried out and the repairs must be verified as per below. 

1. There should be no evidence of water ingress within the liner.

2. The sleeve should be watertight internally.  Where bends or other pipe deformities are present the maximum wrinkling allowed is 3% of the pipe diameter.

Pressure Testing

 If required by the owners bid documents, testing may take place by placing two push rod plugs to the beginning and the end of the sleeve.  Air is fed into the isolated area and pressure losses are monitored. 

Test criteria and acceptable losses to be determined in advance by the engineer in consultation with the contractor.

 Design Considerations 

The design is based on the assumption of a partially deteriorated pipe.  The CIPP is designed to support the hydraulic loads due to groundwater, since the soil and surcharge loads can be supported by the original pipe.  The groundwater level should be determined by the purchaser and the thickness of the CIPP should be sufficient to withstand this hydrostatic pressure without collapsing.   

Brief Description 

Method statement:

 The pipe must be clean and free from debris, encrustation, and standing water.  Using a camera measure the length of felt tubing required.

 Insert the fiber liner tube into a bladder tube.

 Mix the resin and hardener required and pour the required amount of resin into the tube. 

Attach a Vacuum pump to the other end of the tubes and feed the material through the nip roller, spacers and conveyor system.  Adjust the speed of impregnation to ensure thorough wet out on both top and bottom.

 Carefully wind the fiber liner bladder combination into the tan ensuring tension at all times.  Turn the trailing end of the bladder back on to the nose cone.  Strap the tubes to the cone using a ratchet strap.

 Introduce regulated compressed air (Max 6psi) to the tank and allow sufficient bladder tubing to extrude out.  Deflate the tubing by venting out the air.  Tuck the tubing into the pipe run.  Switch on the compressor and allow the pressure to build up to 6psi by holding the winding arm.

 Gradually unwind the arm at a speed that maintains 6psi pressure until the bladder tubing is fully everted into the pipe and comes out at the required terminations point or the downstream manhole.

 Connect the boiler to the shaft of the tank and introduce warm water at the prescribed temperature whilst allowing the air to escape through the relief valve.

 Continue introducing warm water until the water level backs up to a level just above the crown of the pipe.  Leave the combination of tubes until the felt tube cures.

 Once cured, puncture the bladder tube at the upstream end next to where it is clamped on the pipe.  Slowly rewind the arm of the tank to un-invert the bladder tube thus forcing water out into the manhole.

 Preparatory Procedures

 Cleaning of the Main Pipe

 The manhole to manhole section of main pipe must be free of debris, obstructions, scale or any other material that reduces the effective bore of the pipe or loose material which may be pushed forward by the inversion process.

 If inverting upstream, provision needs to be made for reducing the flow to no more than 15% of the bore of the pipe.

 Pre-repair survey

 A videotaped survey must be done on the main run with a pan and tilt camera to confirm the proposed repair falls within the limitation parameters set by the manufacturer on the following aspects:  The presence of bends, groundwater infiltration, flow rates from laterals and through the main pipe, gradient of pipe run.

 Repair Process

 On completion of the survey, a report should be submitted to the Engineer confirming the feasibility and the required program of works.

 Post Repair Survey

 On completion of a given run, video taped evidence must be provided by the contractor.  The repair sleeve should be monitored for excessive wrinkling, exposed unwetted fibers and pinhole leaks.

 Testing

 Subject to the result of the Inspection test, the Engineer reserves the right to select approximately 10% of the repairs for further testing using water.  The test shall comprise of pushing a plug to the downstream end of the sleeve, inserting a bypass plug at the upstream end and filling the isolated section with water.   Losses shall be measured and must be within levels set by the local code.

 If the failure rate exceeds 10% and additional retest area of an equivalent size shall be selected for further testing.

 Quality Assurance

 The workmanship of the works shall be warranted for a period of 12 months following substantial completion.  The material shall be warranted as per terms and condition of the manufacturer for a similar period PROVIDED the contractor applies the product in accordance with the current guidelines (Standard Operating Procedure) set out by the manufacturer.

Manhole to Manhole Re-lining images: