Tuesday, October 26, 2021

Trenchless case studies from China

The most common rehabilitation methods used in China are UV CIPP, felt liner-hot water, spiral wound, SIPP, and thermo form (FIPP) in sewer pipeline.

In 2021, according to Chinese government statistics, the national pipeline network is made up of approximately 920,000 km of urban water supply pipe, 744,000 km of sewer pipe, 778,800 km of gas pipe, 400,000 km of heating pipe, and 169,000 km of long-distance oil and natural gas pipelines. In total, this exceeds 3.1 million km, which is 4.5 times the length of pipeline in 2000, representing an annual growth of approximately 13.17% over the past 20 years.

However, despite these impressive numbers, pipeline construction is behind schedule and more pipelines need to be updated and rehabilitated due to the low quality of construction materials and poor site management. There is an urgent need to promote new technologies to achieve high-quality construction of the national pipeline network.

The most common rehabilitation methods used in China are UV CIPP, felt liner-hot water, spiral wound, SIPP, and thermo form (FIPP) in sewer pipeline.

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UV CIPP

The Chinese UV CIPP market is unique in the world as nearly all UV technologies from Germany are being used in China, for example I.S.T, ProKasro…etc and 6 more Chinese UV manufacturers, including UV Led technologies. Normally the curing pipe starts from DN300, there are no laterals, only main sewer pipes and 20-plus liner suppliers that have facilities all over the country including iMPREG and Saertex facilities.

Case study from iMPREG (Suzhou) Co, Ltd. – January 2021

A relining company from Shanghai successfully completed a DN1400 storm pipe rehabilitation over 187.2 m in 5 sections in Jingan district, Shanghai. The company used a German-made UV rig to cure the iMPREG liner GL16, with 11 mm wall thickness delivered from the Suzhou facility. The job required one shot curing for each section and the challenge was the low ambient temperature of -80C during the night in January and the 600 mm diameter of the manhole entry. It took 5 nights to cure all 5 sections and with permission from the local authorities, iMPREG was allowed to expand the manhole.

Case study from Shanghai Yufan Co. Ltd. – 2019

This was the second time Yufan had been required to cure a DN1800 pipe since 2014. Over the past few years, Yufan has been committed to the improvement and innovation of the construction process for felt liner hot water curing and has carried out standardised operations and improvement on vacuum extraction of lining hoses, resin mixing, grouting, impregnation platform and on-site construction. Now

it takes 30 minutes to mix the resin compared to 2-3
hours previously, plus 5 workers to impregnate the liners compared to 10 in the past. Additionally, with the new impregnation platform, the thickness of the liner can be accurately adjusted and controlled which means the surface of the liner is smooth and uniform without any white spots or wrinkles.

The DN1800, 7m deep pipe was successfully cured using felt liner-hot water in Guangzhou, following a complete pre-treatment and efficient impregnation.

Spiral wound

Case study from Tianjin Yitong Co. Ltd. – March 2021

Tianjin Yitong carried out the successful installation of a DN2200, 203 m long pipe with its own technologies developed in-house – a spiral wound lining in the Jiujiang section of the Yangtze River Protection project. This was a new record for Tianjin Yitong to complete such a big pipe rehabilitation with a spiral wound method.

Cracks and water leakage appeared in a DN2200 concrete reinforcement pipe and the structure of the entire pipe was repaired using a spiral wound lining – a steel-plastic reinforced construction method. Using 91-25 profiles and stainless-steel strips, a new lined pipe was formed by using a spiral wound liner in the original pipe. After installation, grout was injected into the gap between the new and old pipes. The new pipe was formed with a reinforced high-stength, steel-plastic which would ensure good water tightness.

Thermo form (FIPP)

In China, thermo form pipe is known as FIPP (Formed In Place Pipe). FIPP is widely used in sewer and potable pipe rehabilitation due to lower costs, easy operation, more flexibility, less curing time, high efficiency and less pollution-emission.

Case story of from Chongqing Kenawei Co., Ltd. – March 2021

FIPP units and liners are manufactured by Taiyuan Changdahuamei Co. Ltd.

Kenawei, an inspection and relining company from Chongqing, South West of China, successfully rehabilitated a DN600 sewer pipe by FIPP on March of 2021 in Yongchuan, Chongqing. It took only 4 hours to complete the whole job and just 10 minutes to insert 50 m of liner into the pipe which was then cured at ambient temperature.

SIPP

Case study from Shanghai Yutong Co., Ltd. – 2019

In one district of Anhui, the upstream sewage discharge is less than 5,000m3 yet the actual incoming sewage to the wastewater treatment plant is nearly 40,000m3 and the incoming sewage Chemical Oxygen Demand is less than 20. The main pipe connected to the wastewater treatment plant is 10 km long and includes 800 manholes. The conclusion was that there was too much infiltration from the pipe and manholes. Therefore, Shanghai Yutong rehabilitated all 800 manholes with a polyurea coating, developed by its own in-house technology team. In total, there was 12,000 m3 of coating including 11 m3 for 700 manholes and 40 m3 for 100 manholes. The works, resulted in a 90% reduction in infiltration.

Thanks go to the Underground Pipeline Committee of CACP for the co-ordination of these works.

By Daniel Wu, I.S.T. Innovative Sewer Technologies China

I.S.T. Innovative Sewer Technologies GmbH is one of the world’s most successful and innovative full-service providers in the field of pipe and sewer renovation. The rapidly growing company was founded in the spring of 1998.

I.S.T. China, located in the country’s heart, Beijing, was founded in August of 2019 and was the 6th subsidiary of I.S.T. Germany in the global market. The company aimed to offer the best possible support and immediate expert service on site. In addition to the complete range of I.S.T. products, I.S.T. China also offers cleaning, coating and lining machines from Picote, global pipe inspection software from

CD Lab, and manhole inspection camera from KEPSO. With an area sales network and service partners all over ChinaI.S.T. china offers customers only the very best solutions.

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