Which pipe is most suitable for different microtunneling projects?

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Pipe selection can make or break a project so to speak; the wrong pipe can make a project more difficult to complete, increase time and cost, or at worst fail, while the right pipe will help reduce risk, improve accuracy, reduce costs and improve success overall installation.

But with a number of pipe materials available, how do you know which is best for your application? It comes down to a number of factors – some of which have a greater impact than others – including ground conditions along the pipeline route, installation method, budget, type of application, lead time and specifications such as diameter.

Terracotta pipes

Clay pipes are resistant to most chemicals and are ideal for areas with acidic or contaminated soil conditions. As they are totally inert and rigid, they have high abrasion resistance, low coefficients of friction and high load capacity.

• Suitable for: gravity flow sanitary sewers
• Not suitable for: pressure applications
• Diameter availability: eight to 24 inches
• Lifespan: more than 200 years

Ductile iron pipes

Ductile iron pipes have high reliability as they are ductile, strong and resistant to impact and corrosion, making them ideal for high pressure applications, as well as for pipelines that pass under areas of extreme traffic, heavy fill or earth movements.

• Suitable for: gravity and pressure applications, including potable water, sludge pumping, wastewater and process chemical applications
• Diameter availability: 3 to 64 inches
• Lifespan: indefinite if properly designed and installed

High Density Polyethylene (HDPE) Pipes

HDPE has good resistance to abrasion, corrosion and chemicals, but its use is limited when deadlines are tight, due to the need to tension the line to reduce installation time.

• Suitable for: all underground networks
• Not suitable for: high temperature or pressure applications
• Diameter availability: 3⁄4 to 65 inches
• Lifespan: 100 years minimum when properly designed, installed, inspected and used
• Possible installation methods: HDD is generally used because it requires an exit trench, which is detrimental to the construction of the well and the overall advantages of the keyhole pipeline of microtunneling. However, the AXIS Laser Guided Drilling System offers microtunneling facilities for HDPE pipes using a shrinkage method

Centrifugally cast glass fiber reinforced plastic (CC-GRP) pipes

CC-GRP pipes such as HOBAS have a number of economic advantages, including corrosion resistance, high stiffness, smooth inner surface and oversized inner diameter, as well as tight joints.

One of the main advantages is that they do not require a packing ring which is considered the weakest point of a jacking pipe. They can be economically designed for non-pressure and pressure services by varying the amount, placement and orientation of fiberglass reinforcements, making them versatile and ideal for almost any large diameter corrosive application .

• Suitable for: potable water, main or gravity sewers, and all applications where there is a corrosive carrier or external environment
• Diameter availability: 18 to 158 inches
• Lifespan: more than 100 years

Polyvinyl chloride (PVC) interlocked pipes

PVC is well known for its performance, but is generally limited to installation in areas with constant, self-supporting ground or in casing pipe, as they are generally not suitable for jacking installation.

There may be additional costs associated with these pipes as they have collars which require the use of centralizers to eliminate wear, and most contractors will recommend sealing the annular space to prevent deflection of the pipes due to loading punctual.

• Suitable for: potable water, reclaimed water, sewer lines, sanitary gravity sewers and storm sewer pipes and fittings
• Not suitable for: high temperature or pressure applications
• Diameter availability: pressure pipe is available from 4 to 60 inches, while gravity sewer pipe is available from 3 to 60 inches
• Lifespan: more than 100 years when designed, installed and used correctly
• Possible installation methods: generally best suited for sliding liners and hard drives, but there are now limited options for lifting and removal without clamps, which can increase installation accuracy and reduce risk

Steel tubes

Steel pipes have good strength, durability and elasticity, making them ideal for applications where high internal and external pressure resistance is required. These characteristics also mean that steel pipes can be installed using a number of methods including HDD, jack and pipe reaming and ramming.

• Suitable for: water and waste water, gas and oil, water well casing, pile driving and casing sleeves
• Not suitable for: chemical or corrosive service without internal or external protective coatings
• Diameter availability: pressure pipe is available from 4 to 60 inches, while gravity sewer pipe is available from 3 to 60 inches
• Lifespan: more than 100 years when designed, installed and used correctly

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