GOTEBORG, SWEDEN — Some water companies in Britain have not had good luck with PVC pipes.
At least one study shows PVC water mains there breaking at a higher rate than pipes of other materials. But a major U.S. trade organization believes the problems are unique to the British Isles.
Keith Edwards, head of innovation for Anglian Water Services in Huntingdon, England, for one, is not a fan of PVC pipes.
And he didn't mind telling that to about 200 delegates during a presentation at the Plastic Pipes X conference in Goteborg Sept. 14.
``I'm not a great supporter of PVC because we now spend a lot of time digging it up and replacing it,'' Edwards said.
Borealis AB of Denmark, which makes resins that compete with PVC in the pipe game, co-sponsored Plastic Pipes X with the Institute of Materials in London, which is holding a PVC-only show in Brighton, England, in April.
Edwards was not opposed to all forms of plastic pipe, and during a question-and-answer session said he would ``love to see more plastic pipes.'' But he leaned toward polyethylene as the material of choice.
His comments followed those of Roger Stokes, a professor at the University of East London, who studied the long-term reliability of Anglian's plastic pipes.
``Plastic pipes have a future [in water distribution] as long as consumer concerns are dealt with,'' Stokes said.
Stokes reported that old, iron pipes make up about 40 percent of the British water-distribution network. The aging process has caused problems with corrosion, and now plastic pipes comprise about 75 percent of the new installations in the United Kingdom. PVC is being used mainly for larger diameters, and polyethylene is more common for widths less than 6 inches.
But Stokes said even relatively young PVC pipes, installed in the first generation of such products in the 1970s, are failing at a rate slightly greater than the average for all types of pipe — and at a much younger age than their 50-year design life.
``If one looks back at the history of PVC pipes, there was a pattern of problems early in their development,'' Stokes said after the conference. ``The failure rate at that time was very high — higher than PE today.''
The average age of PVC pipes studied was older than the PE pipes, Stokes noted. But he added early PE pipes failed less than their PVC counterparts at a similar stage in their development.
``Over a comparable period, PE had a much more successful introduction than PVC,'' he said. ``PE pipes have been at least 10 times better than PVC — and maybe more than that.''
Products from about five different British PVC pipe manufactures were used by Anglian before it banned the use of PVC in 1989, Stokes said. One of the products, which had solvent-welded joints, exhibited very high failure rates early on and was discontinued. That product may have skewed the overall results, but other PVC products still had problems, Stokes said.
``While PE has some problems, it seems evident that this pipe material is much more tolerant of abuse that arises during installation and subsequent operation than PVC,'' he said. He noted most PE pipe failures occur at joints, while PVC pipes failed elsewhere.
Stokes said the results of his study are ``worrying,'' but added the statistical analysis raises more questions than answers.``A lot of further study is needed,'' he said.
The British experience with PVC was fairly unique, Robert Walker, director of the Uni-Bell PVC Pipe Association in Dallas, said by telephone Sept. 24.
``PVC, like any other material, if not properly manufactured is not going to perform as well,'' he said.
``We heard about these problems [in England] and they were alarming to us in North America, where the performance record of PVC pipe has been second to none,'' he said. ``The British market really is an anomaly. We have not had those types of situations occurring in our country or other parts of the world.''