More than 50 years ago, Vesconite bushings helped solve a wear problem in a submerged pump at a South African Railways (SAR) water-reclamation plant in Bloemfontein, South Africa – and far exceeded the lifespan of the bronze bushings that were replaced.
The pump handled approximately 500,000 gallons (2.3 million litres) of runoff per day, carrying around 15 tons of sand, silt and ash. Based on these figures, the suspended solids load was approximately 7 grams per litre.
According to the case study from Vesconite Bearings’ archive, the original bronze bushings wore out within only a few hours in this challenging pumping environment.
The bronze bushings were replaced with two Vesconite bushings. The lower Vesconite bushing operated continuously for three months before requiring replacement, while the upper bushing did not require replacement during the recorded three months. The information shows that the Vesconite installation extended bushing service life by one to two orders of magnitude compared with bronze for the lower bushing, and many times more for the upper bushing, which lasted an unspecified period longer.
The case study illustrates an important principle in abrasive-water pumping. The bushing material must not only support the pump shaft and allow relative movement. It must also withstand the combined effects of water and suspended abrasive particles over extended periods.
More than five decades after this Vesconite installation was recorded, the engineering challenge remains relevant. Pumps used for stormwater, wastewater, mining, industrial water and water-reclamation applications can encounter water containing substantial quantities of suspended solids. In such environments, abrasive particles can accelerate wear on conventional bushings and increase maintenance requirements.
