Type 23 Frigate Replacement RO Plant

The original RO desalination plants fitted to the Type 23 Frigates were replaced in the late 1990’s by an alternative plant. However, these proved to be problematic in service, particularly when operating in the North Arabian Gulf.

In February 2008, Salt Separation Services were contracted to provide a detailed study into the problems and issues surrounding these RO plants and to identify an innovative solution.

The study and subsequent report highlighted a multitude of problems, including excessive usage of disposable pre-filters, high failure rate of high pressure pumps, control panel over-heating, short operational life of RO modules (specific to one supplier and very expensive), high failure rate of solenoid valves, excessive use of chemicals and much more.

Ultimately, the decision was taken to retrofit the plants with new RO plants incorporating additional pre-filtration and using commercially available RO membrane technology.

Due to the ships operational programmes, the ‘rip-out’ of the existing plant and the subsequent installation of the replacement plant needed to be completed within a 6 week window for each ship.

In 2009, Salt Separation Services were contracted to design, manufacture, install and commission 13 x ships sets of RO plants for the Type 23 Frigate fleet.

Package Description

Each ships set comprises of 2 x 40 m3/d SWRO desalination plants and 1 x 3 m3/d  technical water RO plant.

The plant design was based on packages previously manufactured for the Royal Navy and fitted to LPD, CVS, CVF, Type 22 and Type 42. Each ships set is fully assembled and tested in our workshop prior to installation. This reduces installation time on-site and ensures that commissioning can be completed in a period of 2 to 3 days.

Each SWRO plant is fitted with media filtration, antiscalant dosing, cartridge filtration, RO membrane desalination and rehardening (c/w CO2 addition) to produce potable water to meet WHO requirements.

The technical water RO plant is fitted with depth filtration, carbon filtration and RO membrane desalination to produce technical water with a conductivity of less than 20 µS/cm.

The packages are fully automatic in operation. The SWRO plants are also fitted with automatic RO membrane cleaning and flushing, thereby reducing operator involvement and increasing the operational life of the RO membrane elements.

The packages have been designed to operate worldwide and have been proven to be very reliable when the vessels have been deployed to the North Arabian Gulf.

Scope of Work

First, we have to surgically remove the existing plant (approximately 8,000 kg of equipment), then we have to install the new replacement plant (approximately 9,500 kg of equipment).  All this is done through the MGR hatch measuring 810 x 600mm!This takes a team of 5 engineers, working from a 20’ ISO container on the flight deck, 2 weeks to complete.

The installation of the replacement plant then takes an additional 3 weeks to complete.

Our engineers work autonomously – no assistance from ships staff or the yard is required except for  lifting operations for the 20’ ISO container onto the flight deck and is subsequent removal.