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Project Spotlight: Water Aid and Threaded Collars

Water Aid:

Clean water, sanitary toilets and good hygiene are basic human rights. They should be a normal part of daily life for everyone, everywhere on the planet – but they aren't. That's why Water Aid exists.

Since the charity’s inception in 1981, Water Aid has delivered clean water to 28.5 million, decent toilets to 29 million, and helped 27.8 million people achieve good hygiene.

The Project:

Our client, Poldaw Designs, contacted Amey Plastics with a view to producing a threaded collar to extend pipeline from a pump cylinder, used to access water located in boreholes deep underground.

The project was particularly challenging because of unusual requirements.

Typically, pipeline is laid horizontally and the pipe joints are subject predominantly to just the forces caused by the pressure of the liquid inside.

However, the nature of this handpump application means the pipe hangs vertically, suspended directly beneath the pump. The pump cylinder, which collects the water at the bottom of the borehole, is suspended from the pipe. As a result of this set up, additional forces come in to play that need to be considered.

In addition to water pressure, there is a substantial tension on the pipe due to the weight of the pump, the weight of the pipe itself, and the weight of the water in the pipe. This in itself is unusual.

Furthermore, during the pumping action, when the pump piston is lifting the water, part (approximately half) of the tension in the pipe is relieved. This happens about 40 times a minute, and many millions of times over the life of the system.

This dynamic raises the issue of fatigue cracking. To mitigate this risk and prolong the life of this essential tool for 100,000s of people, the final design of the threaded collar and adapter has been optimised to reduce the fatigue stresses at the transition between the collar and the pipe. This will help achieve a very long service life.


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