Fold-and-Form Lining for DN400 Drinking Water Pipe

Project Overview

A DN400 water supply pipeline along Xinzheng Road in Zhengzhou, spanning from Nanguan North Street to Zijingshan Road, required rehabilitation. The pipeline, located within a protected area, had been in operation for decades and initially transported water from the Yellow River. Due to the high water hardness, the inner walls of the pipe were heavily encrusted with deposits. The total rehabilitation length was approximately 124 meters. Site surveys revealed six pipeline bends along the route, with the sharpest bend reaching an angle of 50°, significantly increasing the construction complexity.

After thorough evaluation, the decision was made to adopt the Fold-and-Form PVC lining technology, which meets drinking water safety standards, to rehabilitate the pipeline.

Challenges and Solutions

The pipeline's location within a protected area and its condition presented several challenges:

1. Severe Encrustation

The pipeline's long service life and use of Yellow River water with high hardness had caused significant internal scaling and encrustation.

2. Complex Geometry

• The pipeline extended 124 meters, including six bends, with the sharpest angle reaching 50°, making it difficult for cleaning equipment to navigate.

• Bends experienced uneven stress, creating cleaning blind spots that required repeated attention.

3. Cleaning Process

Cleaning was identified as the first critical step for successful rehabilitation and tackled with the following methods:

• Custom Spring Blade Cleaner: Designed in-house to scrape off large deposits.

• Custom Steel Wool Tool: Used for repeated polishing to remove rust and sharp edges from the pipe's inner walls.

• High-Pressure Pulsed Water Jet: Employed to flush out residual encrustations, ensuring complete removal of debris and a smooth, clean pipe surface.

The cleaned pipe walls were required to meet stringent smoothness criteria, ensuring no residual deposits exceeded the thickness of the original coating before proceeding to the next phase.

Construction Challenges and On-Site Solutions

1. Material Hardening at Bends

After the thermoplastic material is softened and pulled into the pipeline, the numerous bends increase the likelihood of the material getting stuck at the elbows, making the insertion process more challenging.

2. Twisting and Deformation

The multiple bends in the pipeline cause the thermoplastic material to twist into a braid-like shape during insertion, significantly increasing the difficulty of the repair process.

3. Increased Friction

The softened material experienced significant friction at the bends, risking damage or uneven thickness distribution.

4. Uneven Pressure During Pressurization

During the pressurization phase, the material at the bends faced uneven forces, increasing the likelihood of wrinkles and affecting the overall lining quality.

Each of these challenges was systematically addressed by adjusting the material softening process, optimizing insertion techniques, and carefully monitoring pressurization to ensure uniform results.

Project Outcomes

The pipeline rehabilitation covered 124 meters, including multiple bends. Post-rehabilitation inspections confirmed the absence of wrinkles or defects, and the project passed all quality standards. The pipeline has been officially commissioned, and the client provided the following positive feedback:

1. Economic Efficiency

The low material transportation and storage costs, minimal excavation and land occupation, and efficient construction process resulted in significant cost savings.

2. High-Quality Results

The thermoplastic material's high toughness and durability made it ideal for pipelines subjected to dynamic loads.

3. Environmental Friendliness

The green construction approach avoided the release of toxic chemicals, ensuring safety and environmental sustainability.

4. Adaptability

The technology effectively addressed the existing defects in the pipeline, including bends, while ensuring wrinkle-free lining and superior flow capacity.

Advantages of Fold&Form Lining Technology

1. Pre-Fabricated Lining Material

The lining material is highly pre-fabricated, ensuring consistent mechanical performance and reliable construction quality.

2. Wide Applicability

Suitable for all pipeline materials and capable of rehabilitating pipelines with irregular shapes, varying diameters, and misaligned joints, as well as pipelines with bends.

3. High Toughness

The material's toughness makes it suitable for pipelines exposed to high traffic loads, metro areas, and seismic zones.

4. Stable Long-Term Performance

Its isotropic solid-wall design ensures stable, long-term performance with excellent chemical resistance and wear resistance.

5. Drinking Water Certification

The thermoplastic material is certified for drinking water use, including NSF-61 certification, ensuring safety and compliance.

This case study highlights the effectiveness of Anyue Fold and Form PVC lining technology in addressing complex pipeline rehabilitation challenges, delivering high-quality, cost-effective, and environmentally friendly solutions.

If you are interested in our products, feel free to contact us via info@anyuetrenchless.com.