Leading pump manufacturer Mather and Platt has harnessed two quite diverse nanostructured materials to achieve greater durability and efficiency in its new range of horizontal centrifugal pumps.
The two drivers behind Mather and Platt’s technology development are the two objectives every public or private sector entity should pursue in order to be effective and sustainable.
Minimising costs and maximising productivity are important contributors to service delivery, and the two critical success factors that Mather and Platt’s new range of horizontal centrifugal pumps, launched 18 months ago, achieve in no small way.
Cast iron and aluminium pumps often suffer from corrosion and/or cavitation as a result of high alkalinity or high acidity. In such instances, a pump’s reliability, efficiency and performance are affected, as well as its power consumption, which substantially increases its lifetime running costs. Minimising performance deterioration is, therefore, a major concern for pump manufacturers and users.
The questions is, how does one limit or prevent these constraining factors? Duplex stainless steel The first of the technologies developed by Mather and Platt is the duplex stainless steel horizontal centrifugal pump, manufactured from grades 4A and 4B stainless steel.
This type of steel is called duplex as it has a two-phase microstructure consisting of ferritic and austenitic stainless steel grains. Initially, when molten duplex stainless steel solidifies, it does so as a completely ferritic structure. Then, as the material cools down to room temperature, about half of the ferritic grains transform to austenitic grains, which form layered islands in the microstructure.
The result is a mix of roughly 50% austenite pumping cold, high-alkalinity seawater through Aqunion’s Roman Bay abalone sea farm corrodes pumps of lesser quality and 50% ferrite.
So, what does this all mean?
Firstly, duplex stainless steels are twice as strong as regular austenitic or ferritic stainless steels. Secondly, it has significantly better toughness and ductility than ferritic grades and, most importantly, it has an exceptionally good pitting resistance equivalent number corrosion value of >40, as well as good stress-corrosion cracking resistance.
It also functions effectively between -80°C and 300°C. Lastly, duplex stainless steels have a better ability to absorb energy of any dynamic or static state. All of this makes for what the company refers to as a near perfect pump.
For example, a large Gansbaai abalone farm, with its cold temperatures and high-alkalinity seawater, struggled with pump corrosion until it installed five LN type split-case super duplex stainless steel horizontal centrifugal pumps, each with a capacity of 1,250m3/ hour to draw seawater under negative suction head from the seawater intake gully.
Not only do they have greater efficiency but reduced running costs as a bonus.
The second of the technologies, using third party developments in microstructure technology, ushers in a solvent-free glasslike epoxy coating that provides excellent adhesion to metal substrates, including stainless steel, duplex steels, carbon steel, aluminium, cast iron and bronze, as well as specialist alloys.
Any fluid passing through its hydraulic passage is subject to resistance caused by friction, the extent of which is determined by fluid viscosity. Hydraulic losses represent most of the efficiency reductions and resultant energy-consumption increases, which are exacerbated by corrosion and cavitation.
The epoxy coating helps to reduce these losses, therefore increasing a pump’s performance. In choosing the best pump, the liquid’s chemistry, the pump head requirement, sump depth, plant layout and pump capacity requirement are all important factors.
If full automation is required, this can be implemented using WIPL’s electronic control gear. Last but not least, as reliability is critical, Mather and Platt pumps are manufactured to ISO 9001 quality certification and backed up by full spares availability and support
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