Durability of Danish PE Gas Pipes [PE]

Over the last 20 years the Danish natural gas distribution network has been using 2nd generation PE materials classified as PE80. When introducing the PE materials (MDPE) right from the start of the Danish gas project expectations were that they would last for more than 50 years. The Danish standard for PE pipes and fittings DS 2131.2 (2.), laid down the norms for not only the individual components (pipes and fittings), but also for their fusability (fitness for purpose). DS 2131.2 requires that not only should the pipes fulfil the 10,000-hour regression test for the material in question, but the entire system should be checked against the regression curve. This is done by submitting all types of applied raw materials in the form of pipes, all applied types of fittings and finally all kinds of fusing methods to each of the minimum 18 test models that form part of a type test. The above-mentioned Danish standard was a unique standard in Europe. In 2000 it was decided to examine the material properties of the Danish PE gas distribution network. The national committee for gas transmission and distribution decided to "carry out a project" with the purpose of testing PE pipes that had been used for distribution for 5–22 years. The carrying out of these tests might result in indications of the prediction of the residual life of the PE pipes. The project was carried out with co-financial and expert assistance provided by Nordisk Wavin and know-how provided by Wavin Marketing & Technology in Holland, and this company undertook the tests as accredited tests. The project was concluded with the report "Durability of Danish PE Gas Pipes, R 9232" of 22 February 2002 (1.). This report will give the replies to the following questions : • • • Did the pipes fulfil the test requirements of DS 2131.2 (2.) and prEN 1555 (3.)? Was there any indication of decomposition of the PE material? Did the tests reveal any reduction in the lifetime of the PE pipes? The report concludes the following : • • • All pipes fulfil the test requirements (applies to the tests carried out) of both DS 2131.2 (2.) and prEN 1555 (3.) There is no indication of decomposition of the PE material The tests did not reveal any reduction in the lifetime of the PE pipes?