All over Japan we have huge agricultural fields to cultivate rice, vegetables, fruits and other crops. Major parts of the pipeline project were developed between 1968 and 1985 by the National development project. Since then over a century passed and the infrastructure became too old. Major problems of our pipelines are leakages, cracks, collapses and corrosion. This is not only harmful to the agricultural facilities but also to the farmer’s property. For the stock management of agricultural pipelines, both human capacity and financial capacity is used.
Next to the agricultural pipelines for farmers, tunnels, pipeline siphon systems by Fiber reinforced plastics mortal, steel pipes, ductile irons and concrete pipes exist in Japan.
Leakage problems occurred in PC pipes, steel pipes and fiber reinforced plastics mortal pipes. The map shows at which part of the pipe the accident exactly happened. According to an investigation report by Mie prefecture, there were 51 accident-cases on pipelines until 2012. In particular within 5 years, they had a total of 25 accidents; a further accumulation of similar incidents can be expected.
Furthermore, in 1994, 2001 and 2009 leakages even led to an outage of water supply for a longer time and thus affected human activity tremendously.
From 2003 to 2011 a governmental research team investigated the given conditions of the main pipelines intensively by evaluating the concrete, neutralization tests, measurement of joint defection, EMF measurement, non-distractive inspection and drilling investigations. The result showed corrosion, abrasion and crack propagation due to degradation over time.
We found leakage problems especially in the joint section at fiber rein forced plastic mortal pipes (600DN) underneath the road. They were not able to transport 100% of the liquids for agricultural purposes any longer. Moreover, a car accident happened due to leakage underneath the road.
We also faced troubles with PC pipes (1350DN) when the ground collapsed due to its leakages and formed a sinkhole. When agricultural, but especially sewer pipes, burst like this, most likely a secondary disaster follows due to contaminated soil or groundwater.
It was confirmed by these investigations that the soil conditions were significantly softened, uneven settled and also showed stress concentration on the fitting and smaller collapses (see picture below) after such a collapse.
Additionally it was confirmed by the surveys that the water quality was contaminated by erosive free carbon dioxide. The carbonation of the cover coat mortal is reducing the pipe wall thickness. As a cause of degraded PC steel wire, the pipes cracked and collapsed.
Especially for agricultural uses, it is very important to utilize pipes with a significant longer life time. It is striking that we need a complete modification to replace our oldest facilities with modern ones in order to provide safe water for agricultural uses. The new ones need to have a sufficient lifetime. Back in the days, we used fiber reinforced plastic mortal pipes, PC pipes, ductile iron and steel pipes.
However those are not durable enough for our needs.
Exclusively with polyethylene pipes we can ensure (or guarantee) the required lifetime and quality for our pipe systems.
Polyethylene pipes retain their characteristics for up to 100 years and longer. PE-pipe was already used for gas applications and as water pipelines around the globe. This is the time to use PE-pipes for agricultural uses.