PVC pipe is the ideal pipiing material for trenchless water infrastructure projects. Here are 10 advantages of using PVC pipes for trenchless pipelines.
- Water Quality - PVC pipe delivers water as clean and pure as it receives.
It imparts no taste or odour to the water it transports, PVC is not a source of lead or other chemical contaminants associated with metal pipe, and does not react with even the most aggressive water. PVC’s smooth non-biodegradable interior wall surface makes it more resistant to bio-film build-up.
Corrosion Resistance / Durability
PVC is inherently well suited for buried applications as it does not corrode internally or externally. This eliminates the need to
specify a corrosion protection method that adds costs and increases risks.
Unlike other products that require protective sleeving or coatings, PVC pipe’s long-term durability is not compromised by minor
surface damage. PVC is corrosion proof and not vulnerable to deterioration from low resistivity drilling muds commonly used
with horizontal directional drilling and other trenchless construction methods. System design and installation are simplified with
a homogeneous wall, and a durable pipe material that doesn’t require liners or coatings. For sewers, PVC pipe is resistant to
virtually all the chemicals found in domestic and industrial wastewaters. In addition, PVC is highly resistant to erosion or abrasive
wear. PVC is not affected by stray currents and requires no cathodic protection.
When properly designed and installed, PVC pipes can handle external loads from over 30m of ground cover and are available
with internal pressure ratings up to 25 bar and pipe stiffness of up to 145,000N/m/m. PVC pipes are also able to bend or flex without breaking, making them ideally suited to handle ground movements caused by instability, shifting soils or earthquakes.
Because PVC pipe is stiffer (higher modulus of elasticity) than other thermoplastic pipes, it offers a much greater capacity for maintaining grade and is less prone to ponding and sagging.
In comparison to other methods of rehabilitation such as Cured-in-Place Pipe (CIPP), which do not necessarily provide structural renewal to the host pipe, sliplining with inserted PVC pipes adds structural renewal to the deteriorated host pipe.
PVC’s immunity to internal corrosion also eliminates tuberculation -– the build-up of corrosion by-products that can reduce hydraulic capacity and increase pumping costs. PVC pipe’s smoother internal wall surface minimizes fluid friction and flow resistance. The need for cleaning and maintenance are eliminated or reduced, thereby lowering operating costs.
Numerous experimental and real-life data provide testimony of PVC’s smooth internal flow characteristics in its long-term performance. For PVC pressure systems, a typical Colebrook- White roughness and coefficient k of 0.01 is widely accepted and used. This equates to much lower lifetime pumping and maintenance costs.
Similarly, the accepted value of Manning “n” for PVC gravity sewer pipes is 0.009. This is significantly lower than that of
traditional piping materials such as clay or concrete.
PVC has been used since the 1950s as both a water and sewer main material, longer than ductile iron and polyethylene. PVC’s proven track record supports expectations of a very long service life. Numerous papers have been published on the long term performance of PVC pipe and it is widely accepted that PVC pipes are capable of 100 + year performance.
PVC pipes for most water distribution applications are designed with gasket joints. These reinforced gaskets form a permanent seal. Water systems can expect zero leakage with correctly installed gasket joined PVC pipes. Fusible PVC pipe joints clearly offer the greatest protection against leakage.
When used for sewers, watertight joints mean less chances of infiltration or exfiltration. Watertight joints significantly reduce the risks of a treatment facility from becoming overloaded.
Consequently, a lower volume of water to treat substantially reduces operating costs. Watertight joints also reduce the likelihood that embedment soil will be washed away, potentially weakening the pipe or nearby structures such as footpaths and roads.
Due to the high acceptance of PVC pipe for water and sewer applications, PVC maintenance equipment, repair parts and appurtenances are readily available in the maintenance store or at the local distributor. There is no need to be concerned with having the proper materials for emergency repairs or routine connections. Many alternative products require stiffeners and other equipment that does not allow the utility to make a quality repair or connection with standard off-the-shelf fittings properly sized for the pipe. The outer diameters of PVC pipes are
compatible with traditional iron pipes, allowing easier and faster connections when renovating pipe systems.
PVC’s coefficient of thermal expansion and contraction is up to four times less than that of alternative thermoplastic pipe materials such as Polyethylene (HDPE), which minimises concerns over proper restraint. The higher modulus of PVC allows immediate connections to be made as it does not require relaxation time after installation unlike Polyethylene.
Crack Resistant Flexibility
PVC pipes also have an ability to bend or flex when subjected to excessive loads. As a result, they develop fewer cracks andnbreaks – another source of leaks and a major entry point for tree roots in the surrounding embedment soils, costly reasons why sewer systems get blocked and need extra maintenance. Water ingress into sewer pipes through cracks and breaks can also increase the volume of wastewater that treatment facilities must process. That, too, can drive up operating costs significantly.
Superior Strength-to-Weight Ratio
Less material is required to manufacture a length of PVC pipe versus an equivalent length of metal, concrete or other plastic pipe. That weight advantage is quite significant. Not only does it make PVC more economical on a length basis, it also conserves resources, lowers transport costs, simplifies and reduces the time needed for installation, and decreases the number and severity of injuries for installation crews. Collectively, these advantages result in lower installed costs.
PVC pipe has the lowest embodied energy and carbon footprint of all pipe types. Life cycle assessments have consistently shown PVC pipe to have a lower environmental impact of all pipe types. PVC by weight is 57% derived from salt, an abundantly available natural resource.
For more information on the benefits of using PVC pipes for trenchless pipelines, Download When Water Quality Matters, Corrosion is Not Sustainable Report