Seawater Self-Priming Pump Eliminates Submersible Pump Downtime
In our latest case study, we were approached by a customer who was frequently experiencing downtime with their submersible pumps used for industrial plant cooling. The pumps, submerged in a port, were tasked with cooling process equipment, yet the system was underperforming.
They were using three submersible pumps for seawater cooling—two in duty/standby and one as backup—but faced ongoing operational issues. The customer was experiencing 5 separate issues caused by the use of submersible pumps within the installation. These included:
Frequent Corrosion
Due to lack of material options, the submersible pumps utilised were only available in a handful of materials meaning cast-iron motor casings were used in place of more corrosion-resistant materials increasing susceptibility to corrosion and reduced service life.
Seal Failure
The cable entry point in a submersible pump is one of the weakest, most easily damaged and vulnerable points of submersible designs. As the cable entry point in this design was through a mild steel outer casing prone to corrosion, as the entry point suffers chemical attack, its dimensions reduce and clearances enlarge meaning it becomes increasingly difficult to create a seal or maintain its integrity.
Excessive wear
The submersible pumps were located on a seabed which due to tidal movements, and increased port traffic, increasing amount of debris was being fed into the pumps causing significant corrosion to casings, damage to mechanical seals and cavitation.
Availability of parts
Submersible pumps often utilise bespoke manufactured parts which are only available from the original manufacturer, as opposed to industrial centrifugal pumps where replacement motors, couplings and other parts are widely available, reducing the potential for downtime.
Sacrificial anodes reduced corrosion but needed regular maintenance
In our client’s pump installation, the motor casings were made from mild steel – a material not compatible with seawater, meaning sacrificial anodes were fitted to prevent corrosion.
However, this created another problem. As these anodes are sacrificial, they had to be replaced every three months however to undertake anode replacement a crane as well as multiple operators had to be used.
What did we specify for our client?
To eliminate the client’s issues, we specified an electric high-flow self-priming pump in duplex stainless steel to seamlessly replace the existing submersible seawater intake pumps.
Duplex stainless steel is a high-performance alloy which provides reliable performance in harsh, chloride-rich marine environments. The pontoon-mounted pump provides a 5–6 m suction lift and delivers over 240 m³/h of drawing seawater via its baseplate-mounted priming pump.
To stop the high-flow priming pump being corroded by the seawater spray and the corrosive atmosphere we protected it with C5 marine coating.
If you have an application that requires a rethink and need expert, impartial help and advice, speak to North Ridge Pumps to see how we can help.
