TPi October 2010

pipes PVC, PE & XLPE

Innovation in the PE pipeline By Richard Graty, marketing manager, GPS PE Pipe Systems

Richard Graty

“ Large alder trunks, with bark remaining, had been bored through with an auger to create a 5cm pipe for the water. The individual lengths were connected by rectangular slabs of oak, without any use of iron or lead fittings ”. This account, given in 2005 by an archaeologist working at the Vindolanda Roman fort, inNorthumberland, England, describes a timber water main installed approximately two millennia before it was unearthed. Water is thought to have been supplied from a nearby spring and distributed around the fort through the main and a network of similar wooden pipes, fastened together by oak pegs. It is perhaps curious that the Romans were using timber pipes at a period when they were already masters of pipe production in lead and terracotta, and had built brilliantly engineered aqueducts serving urban populations. Yet the fact that water was still ‘on tap’ (or at least, flooding daily into the archaeologists’ trenches at Vindolanda just five years ago) is testament to this ancient pipe making technique. More importantly it illustrates that pipes were, even then, becoming diverse in their design and construction. Rather than adhering to the most technologically advanced solution of the age, pipe makers used locally abundant materials to minimise cost, time and effort. The exploration of new materials for pipes and pipe fittings has since produced a wealth of options, leading to the widespread use of polyethylene pressure pipe systems.

to Roman potable water pipes as it is today. Flow was achieved by gravity and siphoning, and common practice was to allow water to flow continually at the point of use. In the case of lead pipes this counteracted the damage to public health, as it reduced contact time between the potable supply and the poisonous metal. Centuries after Roman occupation, during the Industrial Revolution, trees were once again playing a part in the history of the British pipe industry, this time in the form of charcoal. Iron was traditionally smelted using charcoal and pipes made from cast iron produced in this way were certainly in use here in the late 17 th century. (Cast iron pipes are actually recorded as early as 1455, in the German town of Dillenburg. However, the economics of manufacturing water pipes in this material were apparently not widely favourable until much later.) As a forerunner of modern pipe systems, cast iron pipes received a boost in 1709, with the appearance of Europe’s first successful coke-fired blast furnace. Abraham Darby rebuilt the existing furnace at Coalbrookdale and fuelled it using coke, which was far better than coal for iron smelting, and at this time was more readily available than locally made charcoal. This was a significant technological breakthrough and laid the foundations for British cast iron production on a large scale. In London, cast iron was used for public water supply from the mid-18 th century, although this was restricted to trunk mains. Examples are documented: approximately 1,500 yards of 12" pipe were laid at Chelsea in 1746 and in

Scotland, Edinburgh subsequently installed six miles of 9" cast iron mains.

At this time flange ends provided the common method of jointing cast iron pipes. It appears this was not particularly reliable, as contemporary engineers recorded numerous failures caused by expansion and contraction, due to seasonal temperature changes. However, in the late 18 th century Thomas Simpson introduced a repair method for flanged pipelines, which used molten lead to join broken pipes. He was credited with developing the run-lead spigot and socket joint in 1785, which accommodated thermal movement more successfully than flanges. The nascent metal pipes industry, with the industrial Midlands at its centre, created companies that were to develop, amalgamate and go on to produce polyethylene pressure pipe for water. It also ultimately led to the formation of the UK’s largest ever single organisation in this field, Glynwed Pipe Systems Ltd. A noteworthy step came in 1862, when A&J Stewart and Menzies Ltd of Glasgow produced the first gas pipes in the UK. In 1895 this company was merged with Lloyd and Lloyd Ltd of Birmingham, thus forming Stewarts and Lloyds. At this point both companies had existed for more than 40 years and had risen to become the largest iron and steel pipe manufacturers in Britain. Around the same period the first UK factories for lead pipe and copper pipe production were established at Ironbridge (Glynn Brothers) and Bilston (Wednesbury Tubes), respectively. The two were later to become united under the name Glynwed. The growth of Glynwed, in parallel with that of Stewarts and Lloyds, culminated in the creation of Glynwed Pipe Systems Ltd in 2000.

Incidentally, the ability to contain water under pressure was not as relevant

Remains of the Vindolanda Roman fort

Lead pipe at the Roman baths in Bath, England

Along the way, Stewarts and Lloyds acquired the Victaulic Company, which

56

Tube Products International October 2010

www.read-tpi.com