Trenchless, Live-Flow Repair Technology for Mechanically Wound Spiral-Wound Pipes

Process Overview

Principle of the spiral winding process: Factory-prefabricated PVC-U profiles and steel strips are fed simultaneously from surface equipment into a winding machine pre-installed in a manhole, advancing via a spiral winding motion. During operation, the male and female interlocking edges of the profiles lock together while the steel strip is pressed into the seam, continuing until the next manhole is reached. Cement grout is then injected into the annular space between the new liner and the old pipe, ultimately forming a new pipeline characterized by high strength and excellent watertightness.

In addition to complying with ASTM F1697 (US standard) and ISO 11296-7 (international standard), this process was incorporated in 2014 into the first national industry standard for trenchless repair and renewal of urban drainage pipelines (CJJ/T 210-2014). The standard specifies that this technology is suitable for repairing entire pipe sections and pipes with structural damage. Furthermore, the *Technical Guidelines for the Remediation of Urban Black and Odorous Water Bodies—Drainage Outlets, Pipelines, and Manholes (Trial)*, issued by the Ministry of Housing and Urban-Rural Development in 2016, specifically identifies the mechanical spiral winding method as the only trenchless rehabilitation process capable of being performed under live-flow conditions.

Scope of Application

1. Repair of semi-structural and structural defects in stormwater and sewage pipelines, including cracking, deformation, joint separation, leakage, and joint misalignment (≤3 cm);

2. Repair of pipe diameters ranging from approximately DN600 to DN2500 mm;

3. Repair of localized defects on the inner pipe wall, such as pinholes, spalling, and exposed aggregate;

4. Emergency repairs for issues such as voids or missing sections at the pipe crown.

Key Advantages and Features

1. Ultra-high strength: The new liner pipe is designed as an independent structural pipe capable of withstanding external pressure on its own. For a DN1200 mm pipe, the ring stiffness can reach 8 kN/m². The strength of the rehabilitated pipeline is derived from the combination of the new liner pipe and the grout. 2. Long installation span: Multiple manhole sections can be rehabilitated in a single continuous operation.

3. Reliable installation quality: The profile is factory-prefabricated, and on-site installation relies on a fully mechanical, physical interlocking process; quality is unaffected by human factors or environmental conditions, resulting in a sealed, high-integrity rehabilitated pipeline.

4. Rapid installation: Depending on the pipe diameter, the winding speed ranges from 1 to 5 minutes per linear meter (based on a profile feed rate of 15 meters per minute), making the method suitable for emergency repair projects on drainage pipelines.

5. Flexible workflow: Installation can be paused and resumed at any time; in the event of traffic congestion or the need for emergency drainage, the profile can be cut and the manhole cover replaced to restore traffic and allow drainage, with welding and installation resuming whenever work restarts.