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What is a Filter Unit

What is a Filter Unit?

Filter Units are designed to protect rivers, shores, bridges and mono piles from scour damage.  A Filter Unit is constructed of mesh net filled with rocks. The units prevent scour without destroying the environment as they provide a natural habitat for plants and aquatic life.

Filter Units are also used to provide environmentally-friendly marine cable protection.

Filter Units are used for…

Filter Units installed for scour protection of foundation of wind turbine

1. Scour protection at the base of wind turbines

Cable and pipeline protection and counter measures of pipeline floating.

2. Cable and pipeline protection and as a counter measure to the problem of pipeline movement.

Adjustment of unevenness of the seabed for cable and pipeline

3. Adjusting an uneven seabed when laying cables and pipelines.

Creation of cable and pipeline crossing.

4.  The creation of cable and pipeline crossings.

Features of Filter Units…

Flexibilty

Cables can be laid on uneven seabed areas without the need for levelling.

Uneven Seabed

Uneven seabed.

As Filter Unit is made of synthetic fiber, it is strong against corrosion that it has a long durability. At the same time, it has durability against ultraviolet rays equivalent to 30 years exposure under the sun.

Filter Units are used to fill in gaps on an area of uneven seabed.

Ease of Installation

As Filter Units are flexible and fit well together it is possible to easily add more as needed.

Filter Unit is installed.

Filter Units installed on seabed.

Filter Unit will follow the fluctuation of ground even if it is scoured from outside the structure and sinks.

The units will follow the structure of the seabed even if scouring or sinking occurs.

It is very easy to carry out remedial work.

It is easy to carry out remedial work or to add more units.

High Productivity

For cxample, carrying out maintenance on a rock dumping site.

Rocks are covering marine cable.

Rocks covering marine cable.

A part of dumped rocks are washed away by flow of water.

Rocks are washed away by flow of water.

Repair work at damaged part of rock dumped area by Filter Unit.

Repair work using Filter Units.

Cost Effective Installation

It is possible to install multiple Filter Units at once by crane.

Filter Unit is installed.

Image of installation of three Filter Units at one time.

Scour Protection and Suction Prevention

Filled stones which creates multiple layers and high covering effect, Filter Unit protects seabed from scouring and sucking.

The layers of flexible units provide high coverage protecting the seabed from scouring and sucking.

High Durability

As Filter Unit is made of synthetic fiber, it is strong against corrosion that it has a long durability. At the same time, it has durability against ultraviolet rays equivalent to 30 years exposure under the sun.

As Filter Units are made of synthetic fibre they can withstand corrosion and have excellent longevity, e.g. 30 years durability to ultraviolet rays.

Weather test of net (acceleration test of ultraviolet rays irradiation for 7500 hours equivalent to 30 years' exposure under the sun.)

Weather test of net (acceleration test of ultraviolet rays irradiation for 7500 hours equivalent to 30 years’ exposure under the sun.)

Consideration for environmental issues

Each Filter Unit has a porous structure so it can become a habitat for aquatic creatures.
At the same time, the stable ground created by the Filter Unit becomes a base of growth* for seaweeds etc.

* The growth of seaweeds depends on environmental condition of the sea.

Filter Unit rock bags become a habitat for aquatic creatures
Filter Unit rock bags become a habitat for aquatic creatures
Filter Unit rock bags become a habitat for aquatic creatures
Filter Unit rock bags become a habitat for aquatic creatures

Product Specifications

Shape Of Filter Unit Before Stuffing Stones

Shape Of Filter Unit Before Stuffing Stones

Dimensions In Meters, Filter Unit Installed

Dimensions In Meters, Filter Unit Installed

There is a risk of damage to Filter Units if they are used in certain places:

  • Wave breaking points where waves hit constantly. (The stones could rub the net from inside causing it to break.)
  • Areas where there are a lot of stones on the seabed. Filter Units may be impacted by stones and partially broken during stormy weather.
  • Above applicable velocity of flow is a theoretical value when Filter Unit is installed in seawater.

We recommend using stones of 50mm diameter for 2t & 4t types and 75mm for 8t type. However, it is possible to use a maximum diameter of 200mm for all types.
*Specific gravity of filling stones should be 2.6-2.65.

Civil Applications

Filter Units for Civil Engineering Applications

Filter Units for Civil Applications

Wind, Wave & Tidal

filter units, rock sacks, stone bags, rock bags, mesh net rock bags, flexible rock bags, marine rock bags, subsea rock bags

Filter Units for Wind, Wave & Tidal Applications

Oil & Gas

filter units, rock sacks, stone bags, rock bags, mesh net rock bags, flexible rock bags, marine rock bags, subsea rock bags

Filter Units for Oil & Gas Applications

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