Relining Seals Leaking Joints

Drain pipe failures on joints are usually a result of one of 2 factors: 

Incorrect installation practices or soil movement causing joints to miss-align and leak.

PVC Pipe Joint Failure

Improper installation is the main reason for pipe joint failure on PVC piping.

PVC and CPVC pipes are one of the most extensively used plastic piping materials. The main reason for the great success of these pipes is their low cost, low failure rate, and relative ease of installation. However, as with all piping materials, there are occasional failures.

Below are the most common reasons for failure in PVC piping:

1: Insufficient cement use: 

If an insufficient amount of cement is used, the bonds between the PVC pipe and fitting will be too weak.

The organic solvents in cement soften the surface of the pipe and fitting socket allowing the polymer molecules to intertwine to form a permanent bond. Sufficient cement must be applied to end up with complete coverage of the end of the pipe and the inside of the fitting so that a continuous bond is formed between the pipe and fitting surfaces. If insufficient cement is used, voids may form in the bond between the pipe and fitting. The presence of the voids results in a weakened assembly which may result in water leaking from the joint.

2: Excessive cement on PVC pipes 

PVC is extremely porous, and can break down when too much cement is applied. Absorption of the solvents in the cement into the top layer of plastic in the pipe and fitting socket is necessary to achieve good bonding. The organic solvents in the cement are volatile and quickly evaporate so that they are only around long enough to do their intended job but not long enough to cause the pipe to weaken. The problem is that occasionally installers utilize too much cement resulting in dribbles running down the inside of vertical runs of pipe. The solvents in the cement themselves are readily absorbed into CPVC and PVC; i.e., they readily are absorbed into the wall of the pipe and inside fitting socket resulting in softening of the material.

3: Pipe alignment: 

Pipes must be installed without excessive bending deflection stresses on the pipe. Pipe manufacturer’s instructions should be followed regarding the maximum allowable bending deflections of their pipes. Excessive bending deflection may lead to failure of both the pipe and the fittings to which the pipes are connected. Elbow and Tee fittings are subject to creep failure in the crotch (Figure 9) if pipes are not installed in 90 degree alignment.

4: Deburring/Chamfer of Pipe Ends

When a pipe is cut, it should be cut square and any residue (burrs) that forms on the end of the pipe during the cutting operation should be removed. Further, the sharp outer edge on the end of the pipe should be rounded or chamfered. The rounded edge allows the cement placed on the inside of the fitting socket to be more evenly distributed as the pipe is inserted into the socket as well as helping to achieve complete insertion each time.

5: Short insertion: 

When PVC/CPVC pipes are inserted into fittings they should be inserted all of the way until the end of the pipe hits the stop. If they are short inserted, a pocket remains between the end of the pipe and the stop. This is a place where environmental stress cracking failure may occur.

6: Deburring/Chamfer of Pipe Ends

When a pipe is cut, it should be cut square and any residue (burrs) that forms on the end of the pipe during the cutting operation should be removed. Further, the sharp outer edge on the end of the pipe should be rounded or chamfered. The rounded edge allows the cement placed on the inside of the fitting socket to be more evenly distributed as the pipe is inserted into the socket as well as helping to achieve complete insertion each time.

7: Thermal expansion:

Most plastic pipes have a much higher coefficient of linear thermal expansion than non‐plastic materials. The high coefficient of linear thermal expansion of PVC pipes must be compensated for during installation, especially in environments where large temperature changes are likely. The normal way to allow for thermal expansion is by installation of expansion loops in long runs of piping and the use of loose fitting or roller hangars that allow for slippage. A qualified system engineering professional should be consulted to ensure that the system is properly engineered to accommodate the possible temperature fluctuations encountered by the system and that proper expansion capabilities are incorporated into the system.

8: Contamination – Interior: 

Some products that are used in construction may contain chemicals that are not compatible with PVC/CPVC pipes and fittings. Therefore care must be exercised during installation to make sure that only approved materials (e.g., metal pipe thread sealants, cutting oils, fire caulks, antifreeze, antibacterial lined pipes, etc.) are used during installation.

Earthenware pipe joint failure:

Some complications which can occur with earthenware drain pipes include:

  • a slight movement or settling in the ground around the pipe can disturb couplings and potentially create water leaks
  • subsequent water loss can wash away pipe bedding causing more drain movement
  • because of the shatter-able nature of the clay, cracks or breaks can occur from shocks or impact damage
  • misalignment allows debris to be snagged on the inside of the pipe eventually causing a partial or full drain blockage
  • one misaligned pipe can then nudge the next pipe out of place and so on, causing more and more issues along the drain length
  • heavy vehicle movement over pipes under driveways or roads can cause cracks or even total drain collapse

Traditionally the only solution to fixing leaking pipe joints was to chop open or dig and expose the pipe, and replace the leaking section. But such nightmares no longer need to be endured.

Nu Flow is able to reline leaking drain pipes working from existing access points like manholes and inspection thereby causing absolutely no damage and minimal disruption to buildings and structures.

The leaking pipe is first camera inspected with a CCTV pipe inspection camera  to identify the problematic joints and determine exactly how much of the pipe line is in need of rehabilitation.

The pipe is then cleaned if necessary and then relined with a structural liner, which creates a new seamless pipe within the host pipe sealing over the joint.

No Chopping open!
No Damage!
No Mess!

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