A case study in submarine cable burial
There are many services we use in everyday life that are taken for granted. Surfing the internet, sending emails and talking to family members in foreign countries are all possible at the touch of a button, often without us realising and appreciating the technology involved that enables us to perform these tasks.
There is a common misconception that most international communications are routed via satellites. In fact, over 95 per cent of this traffic is actually routed via submarine. The transfer of information via these cables is not only cheaper but also quicker than using satellite.
In locations close to shore and in fishing grounds, these cables are buried under the seabed to help protect them from damage. There are many causes of damage, such as anchors of large vessels near the shore, or trawling nets in fishing grounds. Here specialist knowledge and superior equipment is vital.
Generally, cables are buried under the seabed in two ways. One option involves a large vessel towing a plow which performs the simultaneous operation of cable laying and burial. The other is the use of a Remotely Operated Vehicle (ROV), which blasts water jets into the seabed to form a trench, to the targeted burial depth, and drops in the cable.
Such a system is used by ASME A/S, a market leader in providing heavy duty equipment for the offshore industry. ASME A/S contacted Xylem Water Solutions Denmark to supply a pumping system to be installed on a bespoke ROV which not only supplied water at a pressure sufficient enough to dig one meter deep trenches, but could also withstand the harsh sea environment at a depth of 400 meters.
For maximum efficiency, Xylem Water Solutions Denmark suggested using two Vogel Pumpen TVS Duplex submersible multistage pumps. With heads of up to 500 meters, both pumps can deliver an advanced spray which ensures the required trench depth of one meter can be met. Also, the pumping system is completely made up of investment cast stainless steel which offers increased corrosion and wear resistance against the harsh sea environment.
Other important considerations for the purchase of the new system was ease of installation and maintenance. An ROV can be subjected to torrential waters and strong currents, so having access to the equipment for planned maintenance can reduce the need for excessive retrieval equipment and man power, which offers further monetary savings on the life of the pump.