Technical Services

Installation Steps

Important Notes

How do you calculate the expansion length of plastic pipes? What precautions should be taken during construction?

△L = △T × L × α Where: - △L: Expansion/contraction length (mm) - △T: Calculated temperature difference (℃) - L: Pipe length (m) - α: Linear expansion coefficient (mm/m·℃), typically taken as 0.07 For example, in the Xinjiang desert, if the temperature rises to 45°C during the day and drops to 30°C at night, with a pipe length of 6 meters, the calculation would be: △L = (45 - 30) × 6 × 0.07 = 6.3 mm At first glance, a 6.3-mm contraction in a 6-meter-long pipe might seem insignificant for R-R connected systems. However, even a small discrepancy can add up quickly—30 pipes, each shortened by 6.3 mm, would collectively result in a total shrinkage of 189 mm. In practice, these tiny contractions rarely distribute evenly across every joint; instead, they may concentrate into one or a few critical areas, causing sudden gaps at specific connections. This could lead to sections of pipe unexpectedly pulling apart within an already assembled system—a phenomenon that absolutely cannot be overlooked. To address this issue in the Xinjiang desert, where temperature fluctuations are extreme due to time differences, installation is carefully timed for after 4 p.m. in the morning and afternoon. Additionally, timely backfilling is carried out immediately after installation, effectively mitigating the effects of pipe contraction and ensuring a stable, secure pipeline system.

What preparations should be made before conducting a pipeline pressure test?

1. A written hydrostatic test plan must be developed, with clearly defined roles and responsibilities for each team member. 2. All pipeline nodes at both ends and along the route—including support piers for blocking plates and thrust blocks—must be securely anchored and meet the design strength requirements. Valves are strictly prohibited from being used as substitutes for pipe blocking plates. 3. Water should be slowly introduced from lower to higher points until the pipeline is fully filled, ensuring all air is completely expelled. The pressure gauge must be calibrated in advance and must have an accuracy class of at least 1.5. Its measurement range is recommended to be 1.3 to 1.5 times the test pressure, and the gauge’s nominal diameter should not be less than 150 mm. If possible, pressure gauges should be installed at both ends of the pipeline. 4. Backfilling above the pipe top must be completed to a height of at least 0.5 meters, and the pipeline must remain submerged for a minimum of 12 hours before proceeding with further testing or installation.

What method should be used to install plastic pipes when crossing a river?

When plastic pipes cross rivers, it’s essential to first determine the riverbed’s geological structure—specifically, whether there’s an impact from river pebbles—and decide if protective walls are needed. Crossing should ideally be done during winter when water levels are low. Common methods include the cofferdam method, pipe jacking, and the float-and-sink technique. Among these, the cofferdam method is widely used. Here’s how it works: A cofferdam is constructed to block about two-thirds of the river’s width at one end of the crossing point. Water inside the cofferdam is then pumped out completely. Once the area is clear, a trench is dug within the cofferdam, and the pipe is laid. To prevent sewage from entering, the pipe openings are sealed promptly. After backfilling is complete, the adjacent cofferdam section is re-established, and the process of pumping, trenching, connecting, and backfilling is repeated until the entire crossing is finished.

According to the Integrated Wastewater Discharge Standards, is a PVC-U drainage pipe suitable for discharge requirements?

According to the Integrated Wastewater Discharge Standard GB 8978-88 and the Water Quality Standard for Wastewater Discharged into Urban Sewer Systems GJ 18-86, graded standards have been established for wastewater discharge, along with detailed specifications outlining the maximum allowable concentrations of pollutants. PVC-U pipes stand out due to their exceptional corrosion resistance and hygienic properties—they are immune to corrosive effects from pollutants, ensuring that the pipes never scale up during water transport. Additionally, PVC-U pipes feature a low roughness coefficient, allowing for high flow velocities and optimal full-flow capacity. Their lightweight design also makes them easy to install and maintain, effortlessly meeting the minimum slope requirements mandated by drainage pipe standards. For these reasons, PVC-U pipes are perfectly suited to meet national wastewater discharge standards and represent one of the most practical and widely used materials for sewer systems today.

What are the common methods for connecting plastic pipes?

1. Flexible connection (R-R interface); 2. Rigid connection (T-S interface); 3. Flanged connection—commonly used for joining plastic pipes with other types of piping; 4. Plastic welding—employed for chemical pipelines that operate under low or no pressure.

Technical Review Meeting for 450-Class PVC-O Pipes for Water Supply

The evaluation committee experts listened to a briefing on the development of this pipe material, reviewed relevant technical documentation, and conducted an on-site inspection of product samples and the production line. After thorough questioning and discussion, they concluded that the PVC-O pipe utilizes a unique process involving both axial and radial stretching, which aligns the long-chain PVC molecules in a highly ordered, biaxially arranged structure. This innovative approach results in superior strength, toughness, and impact resistance compared to conventional PVC-U pipes, while also ensuring an exceptionally long service life—predicted by tests to exceed 50 years.

2016 Water Pipeline New Technology Exchange Conference – Conference Highlights

On the morning of July 8, 2016, at 8:00 a.m., the "2016 New Technology Exchange Meeting on Water Conveyance Pipelines," hosted by the Science and Technology Promotion Center of the Ministry of Water Resources and organized by Hebei Wanfang Olive Plastic Pipe Industry Co., Ltd., was held at the Diangu Hotel in Baoding City, Hebei Province. Over 400 participants attended the event, including experts and technical personnel from water resources departments of provinces (and autonomous regions) such as Hebei, Henan, Shandong, Liaoning, and Xinjiang, as well as representatives from relevant municipal and county water authorities in Hebei, along with professionals from water resource research institutions, planning and design organizations, construction firms, and management units—plus representatives from technology-providing companies, survey and design firms, and entities actively applying these innovative pipeline solutions.

A New Choice for the Anti-Corrosion Chemical Industry—Olive Pipe PVC-O

From August 25 to 27, 2017, the Academic Conference and National Expo on New Materials, New Equipment, and New Technologies was held in Changyuan, China’s “Capital of Anti-Corrosion.” Over 300 experts and scholars from the anti-corrosion industry, along with more than 200 corporate representatives—totaling over 500 industry leaders—gathered in Changyuan to jointly map out the future development strategy for the anti-corrosion sector.

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