Industrial pipe installation - Natural gas pipeline construction work

A Quick Guide To Below-Ground Moling Equipment

There are all sorts of methods for installing subterranean pipes, cables and ducts, but one of the most efficient is below-ground moling, which can be used to install everything from gas pipes and water pipes to sewage mains, heating pump systems and so on.

Here, a mole – or pneumatic-driven machine – is used to create a bore through soil displacement so it can forge its way along the designated route. This minimises the need for excavation as the soil is simply displaced rather than removed, helping to reduce potential disruption and business downtime as a result.

These impact moles come in a variety of different sizes, ranging from approximately 25mm in diameter to 63mm, with the best results seen in compressible soils that can be displaced more easily than the likes of dense clay, gravel, loose sand or cobbled surfaces.

You may also hear this equipment referred to as piercing tools, soil displacement hammers or pneumatic impact moles, but they’re all essentially the same and they all do the same job.

The machines are typically made up of three components: the pneumatic compressor and hoses that produce power (although a hydraulic system can also be used), a cylindrical sheath with a piston and pointed tip (the mole) and the aiming sight, which is used to set the direction of the bore.

A hammering mechanism is powered by the pneumatic compressor and this is what punches the mole further into the ground, penetrating the soil and breaking up any smaller stones it encounters along the way. 

Once the mole has reached its exit pit, the boring process is complete and the mole can be removed, with the pipe or cable then positioned into the resulting bore. This should be relatively easy to achieve because the mole is bigger than the pipe due to be installed, so the borehole should accommodate it with no trouble.

There are many benefits associated with working in this way, including being more cost effective than other traditional trenching techniques, minimal disruption to property, little to no excavation required, minimal environmental disruption and so on.

It’s particularly effective for shorter installation runs such as water mains, cables and ducts, pumped sewer lines, gas lines and oil lines, as well as beneath buildings and other structures, under roads, below waterways and in environmentally sensitive places.

Although it may be easier to work using these machines, it’s essential that any and all work undertaken is either carried out by a professional or be supervised appropriately. 

Minimum depths of 1m must be ensured to prevent bore collapses from taking place and underground surveys must also be carried out so as not to compromise other utilities and pipes that may already be in situ.

If you’d like to find out more about trenchless excavation and the benefits of working in this way, get in touch with the UK Commercial Gas team today.

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