Sea Water Coarse Filtration

APSL Filtration Experience


APSL’s extensive experience in the design and supply of sea water and produced water filters enables us to provide a full range of backwashable filtration solutions including:

  • New Equipment Supply (Internals, Vessels & Packages)
  • Internals Retrofits, Upgrades & Refurbishments
  • Vessel Refurbishment / Replacements
  • Spares Supply
  • Trouble-shooting Support
  • Maintenance Packages, Onshore & Offshore

We utilise the know-how, can do, flexible approach of the APSL team to meet with the demands of our customers, no matter how small or large the requirement.

APSL Twin-Slot Filter


APSL’s Twin-Slot automatic backwashing filter was specifically developed for arduous offshore oil and gas sea water filtration applications. Sea water contains contaminants ranging from silica solids to organic matter and in particular sticky planktons, which, during seasonal planktonic bloom periods are very abundant. In the filtration cycle these sticky planktons along with other debris can bind to the filter screen and become extremely difficult to remove without the use of a high performance backwash system. The design features of the APSL Twin-Slot filter, with its highly efficient backwash mechanism, also make it ideal for dirty applications such as oily produced water treatment where the presence of oil binds contaminants to the filter screen. 

Twin-Slot Filter Design


 In order to provide maximum flow flexibility the Twin-Slot strainer is available with 1, 3 or 4 high performance slotted wedge wire screens installed in a common pressure vessel. Each screen is also available in a range of capacities and filtration sizes ranging from 25  to 2,000 µm. The unique profile selection of the APSL wedge wire screens provide an economic, high flow design, which enhance both collapse and burst pressures. Lower filtration levels down to 2 µm are also available with our Twin-Slot+ elements, which incorporate an outer fine filtration layer to achieve very separation sizes.   

 Standard filter screen materials are SS316L, Duplex and Super Duplex, but alternative materials such as Titanium are also available on request. The filter internal assembly, which includes the slotted wedge wire screens, the backwash mechanisms and internal gearing of the multiple screen unit is of a very robust and reliable design that provides maximum uptime even under the most arduous of operating conditions. 

 Twin-Slot pressure vessels can be designed to any pressure vessel code such as ASME VIII, PD 5500, EN 13445, AD Merkblatter or Stoomwezen. The pressure vessel housings are available in a wide range of materials including lined carbon steel, SS316 / 316L, duplex and super duplex, but alternative materials such as 254 SMO, titanium and FRP are also available.