Takashi Kuriyama, Kenji Mizukawa, Hiroyuki Kurio, Hiroaki Sakamoto
# 2010 Vancouver
The Great Hanshin Earthquake that occurred on January 17, 1995, caused devastating damages to a large number of architectural structures such as high-rise apartment houses, and civil structures such as roads and bridges. This earthquake triggered the review of the quake-resistance standards of buildings and civil structures in Japan.
The damages on the part of lifelines were also tremendous. In particular, damages to the water supply pipelines were exposed, in terms of supply of not only potable water, water for medical services, but water for firefighting activities and many others.
On the other hand, no damage was witnessed with Polyethylene Conduits for gas transportation. In the water works as well, attention came to be focused on pipe materials having excellent earthquake-resistant quality. For water supply since then, our association has been active in developing the use of Polyethylene Pipes with PE100 as the main material (PE100, SDR 11, Blue color)
Based upon its conclusion that, in order to overcome so many issues surrounding the water works it was indispensable for all waterworks utilities to establish their management strategies and put them into systematic implementation, the Japanese Ministry of Health, Labour and Welfare publicized The Waterworks Vision in 2004, presenting the future image of our waterworks which should be the common target of the waterworks utilities as well as the specific measures and processes to bring them into realization. The Vision requires the waterworks utilities themselves to analyze and evaluate the present situations and future prospects to make up their future images and realization methods to aim at.
One of the measures indicated in the Waterworks Vision is to realize 100% earthquake resistance with the key pipelines. (In Japan, earthquake-resistant pipes are 1) ductile iron pipes equipped with earthquake-proof joint, 2) steel pipes with welded fittings and 3) Polyethylene Pipes for Water Supply equipped with heat-fusion fittings. ) With the government assistance in expenditures, Polyethylene Pipes for Water Supply have shown the biggest growth among the three competing pipes.
The coverage of the water supply system in Japan is shown in Fig. 1.1. It started to expand rapidly in 1960’s and exceeds 97% at present. Effective replacement will be required, as the pipelines installed then are now decrepit and demand for their r replacement is sure to increase. Replacement of decrepit pipelines is a major subject for the Japanese waterworks utilities to solve.
However, many of the Japanese waterworks utilities suffer from financial difficulties, which delays the replacement proceedings. At present the rate of pipe replacement is around 1% every year in Japan.
Polyethylene Pipes for Water Supply are designed by using MRS(minimum requiredstrength) at 20℃ and 50years.
In view of the fact that their longer lifetime is expected by many waterworks utilities in Japan. we, P0LITEC, have commenced our studies to theorize on the minimum 100 years lifetime of Polyethylene Piping Systems for Water Supply.
