Casting replaces spinning process
In one of the longest established industrial areas of the country, pipe manufacturing is still going strong. Peter Minting visited Stanton Bonna's plant near Ilkstone in Derbyshire
Sales of concrete pipes in the UK are falling this year, with 2000 sales down 50% on 1999 and the first quarter of 2001 35% down compared with the first quarter of 2000. According to Concrete Pipe Association (CPA) spokesman Keith Daniel: "Our hope for privatisation was that investment would be better phased, but in fact we've seen the sit-uation worsen. Water company engineers think there is a ser-ious problem. In AMP3 Ofwat has effectively cut back spending on sewerage by a third."
To boost profitability Stanton Bonna has diversified into other areas including the making of concrete railway sleepers. The company has invested in a new sleeper production unit and is now hoping Railtrack will be forced to invest in Britain's railway network. According to Stanton Bonna's managing director and CPA chairman Barry Cooper: "Rail is not often used for concrete pipe transport in the UK, because delivery times are restricted and unreliable. Most pipes are transported by road."
Despite concerns about cutbacks on sewerage expend-iture, Cooper is confident Stanton Bonna will continue to grow and improve efficiency. The company has invested in casting machines which can produce all of Stanton's off-the-peg products from 300mm-1,800mm in diameter. Concrete jacking pipes used to be made by a spinning process but this has been superseded at most factories, including Stanton Bonna, by a computer controlled vertical casting process.
Pipes are cast using vibration to compact a semi-dry concrete mix into the mould. The pipes are made of Portland cement or a mixture of Portland cement and pulverised fuel ash (PFA). The casting cycle now takes as little as 45 seconds with the input composition closely controlled to ensure the pipe can maintain its shape immediately once released from the machine. The Vi-king machines can produce 160 pipes in an eight-hour shift.
Vi-King pipes will not join to any other cast or spun pipes as they feature a 'Delta' rather than circular gasket, which makes jointed sewers more stable. Pipes can be cast with a number of features including uni-junctions, fixed-branch junctions, pipe bends and lugs for safe lifting. A standard length pipe and rocker pipe allows a section of main sewer to withstand manhole settling.
Manholes are produced in a variety of shapes and sizes from 900mm to 3,000mm in
diameter, with or without plastic-coated steel rungs for easy access. A perforated
chamber version is available which can act as a soakaway unit. Other drainage
products made by Stanton Bonna include Moduloval sewer sections and rectangular box culverts