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Double your money with zirconia ceramics - part two

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Oilfield Technology,

In the second part of this two-part article, Ray Mouw, Morgan Advanced Materials, continues his discussion on why magnesia stabilised zirconia ceramic components will be vital for pumps that work in harsh environments, such as oil and gas, and crude oil extraction.

Energy to burn

Nilcra Zirconia parts are not just beneficial for reducing maintenance costs and extending the life of the pump. The other side of running a pump is managing the operating costs. When stainless-steel and cast-iron components wear, the sealing gaps increase. This reduces the pump’s efficiency – so they need to work longer to pump the same amount of product – or cannot meet the desired pump pressure. In other words, the pump needs more energy to pump the same amount of oil through. Ultimately, becoming less and less efficient.

The energy to run a pump is typically between 40 and 70% of the lifecycle costs – so maintaining sealing gaps and pump efficiencies is important. When pump efficiencies drop below the desired threshold, pumps are taken offline and overhauled – another costly and time-consuming exercise as many tens of thousands of dollars are wasted (per pump per overhaul).

Perhaps more importantly though is the cost of downtime and loss of production once the pump needs to be decommissioned and overhauled. In some cases, a pump can produce AUS$740 per minute, making it easy to see why operators do not want downtime to be a regular occurrence.

Zirconia vs ferobestos – swelling at sea

Another common material that partially-stabilised zirconia stacks up well against is ferobestos. Ferobestos is a fibre reinforced composite material and is often chosen to create the sleeves or bearings on heavy duty pumps, as they provide an excellent seal with minimal leakage. However, ferobestos, is subject to moisture absorption, causing the parts to swell and increase running friction. This then affects the pump performance and causes rapid wear on both the mating parts.

Magnesia partially-stabilised zirconia does not suffer from this issue, as it is a solid monolithic material. This also means it is not subject to hard abrasive wear particles embedding into it and scoring the mating shaft, which can be a very expensive repair exercise.

One such instance that has been noted by an operator is a pump with 2 in. shaft for waste/holding dam pumps, in Longford Australia. An open vane pump in the bottom with ferobestos sleeves were only lasting between one to two months due to swelling and fast wear rates.

Following consultation with Morgan, the sleeve material was changed to Nilcra® Zirconia. The lifespan on these parts is now greater than four years, which has vastly reduced downtime and maintenance costs.

Pumped up parts, pumped up performance

An additional benefit of working with Nilcra Zirconia is that the ceramic, originally dubbed ‘Ceramic Steel’, can in most cases use the same drawing and tolerances of current metal parts. Thus, there is no need for major redesigns and approvals, it is essentially like-for-like. However, the parts can be modified quite easily if required.

Another case Morgan encountered was with a centrifugal pump, pumping ammonium carbonate slurry. The temperature range of the slurry was between 45°C and 85°C, and the shaft speed was running at 1500 RPM, with water to lubricate the pump.

The pump originally had metal shaft sleeves, but the life of the sleeve was only five weeks - a ceramic coating on the pump had a lifespan of eight to ten weeks. Operators of the pump were still finding downtime substantial, maintenance time high and costly, and production was low.

After replacing the shaft sleeves with Nilcra Zirconia ones the sleeves lasted 12 months, a significant ten-fold life increase.

Built to last

As crude oil continues to be a key fuel source for the world, it pays to keep the pumps in good working order and increase operating efficiency.

Only by lowering the lifecycle cost of pumps and maintaining production can operators truly realise better value. Zirconia ceramics can go a long way into achieving that.

Author: Ray Mouw, Morgan Advanced Materials

This is part two of a two-part article. Part one can be read here.

Read the article online at:

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