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A construction site to match the country

News International-French

14 Feb 2011

You can’t have genuine sustainable development without hygiene in general, and wastewater treatment in particular. All over the world, the needs are enormous, whether it is in rehabilitation work or building new facilities. Even if a very broad range of equipment is available, composite solutions have major advantages and can meet very specific needs, as described in this article.

Yiwu is a city of around 1 million people in the greater area of the Yangtze delta. It was founded during the Qin dynasty around 200 B.C. very close to Hangzhou, the capital of the province of Zhejiang. As a trading area of Shanghai, it is known as one of the most influential economic areas in China


A fast-developing region

Due to the region’s leapfrog development over the past few years, the maximum capacity of the local sewer system was soon reached. Apart from this, and despite the city’s large scale investments in the network, the line was in such a bad condition that the groundwater was threatened with pollution. It was therefore absolutely essential to establish a new main leading to the local treatment plant; 12.6 km of Hobas SewerLine® were installed for this purpose in the Yiwu district Choujiang. The undertaking was quite challenging, since the soil in the coastal area of the South China Sea was weak, and therefore difficult for installation.



The CC-GRP pipeline project was conducted in three parts. For the first section, 2.3 km of pipes sized DN 1200 to 2000 were installed; for the second section, 2.9 km of pipes sized DN 800 to 2000; and for the third and longest part, 7.4 km of pipes sized DN 800 to 2000. The complete line was built with gravity pipes and a stiffness of SN 15000. This enabled a cost-efficient installation in great depths and weak soils. The project required a maximum trench depth of 18 m with an average depth of 7 m. The extra-strong pipe proved to be an intelligent and flexible solution that also ensures longterm stability.




JEC Composites Magazine: In general, what are the main problems related to the region's water and wastewater systems?

MICHEL TOBIAS: Many areas lack management capacities for relevant resources.


JCM: What are the priorities?

M. T.: Funding through local budgets or through international programmes such as the World Bank, Asian Development Bank, etc.


JCM: For what types of problems do you receive the most requests?

M. T.: Clients ask for HOBAS Products for two main reasons: 1) corrosion resistance and environmental issues 2) to substitute materials that started to become expensive about two years ago. Markets are trying to avoid the pressure stirring from international raw material players. Only recently it was announced that the iron ore prices that were hiked by the world's leading suppliers may lead to similar metal prices as already experienced.


JCM: Do you specialize in any particular type of solution?

M. T.: HOBAS has been on the Middle East and Asian Pacific market for over 25 years. We have been "making things happen" for almost every application regarding water and wastewater. We are a general specialist so to say.


JCM: Why are composite solutions so well adapted?

M. T.: Compared to other materials GRP Pipes offer more advantages such as high corrosion resistance, temperature insensitivity, long-term durability, light weight, etc. Our CC-GRP material is moreover assembled above ground, by open-dig or jacking. To sum up, the characteristics of our material correspond to the market's needs.


JCM: Hobas is an international player. Do the Asia-Pacific and Middle Eastern regions have strong development potential for you?

M. T.: Due to the strong economic growth in many areas there is a lot of potential. The annual growth for GRP Pipes is predicted to be over 24% in some parts and we will do our best to have our share. To quote a sentence often heard in Asia: "Everything is possible".



Year of construction 2008 - 2009
Pipe length 12.612 km
Pressure class PN 1
Diameter DN 800 – DN 2000
Stiffness class SN 15000
Installation method open cut
Application SewerLine®
Client City of Yiwu



low weight, high stiffness, simple cost-effective installation also in large depths, absolute leak tightness, corrosion resistance


Obvious advantages



The municipality of Yiwu opted for Hobas centrifugally-cast glass fibre-reinforced pipe systems for a number of reasons: 1) the above-mentioned weak soil conditions, for instance, would have complicated the use of heavy equipment. However, because CC-GRP pipes are significantly lighter than other materials, they are easily installed without special equipment. 2) The presence of a road near the pipeline route meant that installation had to be quick, space-saving and flexible at this location to avoid any traffic disruptions; here again, the challenge could be met by using composites pipes, which are easily handled. 3) Leak tightness was another important criterion for the choice of material due to the risk of groundwater contamination. GRP pipes and couplings have been subjected to stringent short- and long-term tests and are provably leak tight. 4) Pipes are often exposed to external influences, especially in coastal areas, so corrosion resistance was yet another crucial factor in the decision-making process. Hobas’ highly corrosion-resistant pipe systems can easily withstand environmental influences.


Full package service

This demanding project started in July 2008 and the pipeline went into service in early 2009. Hobas is the sole provider of centrifugally cast GRP pipe systems in the Chinese market, supplying clients with both the material and the required planning and installation expertise. For this project, the package is already yielding its fruit for all parties involved, who are highly satisfied with the product choice and the cooperation.