Prefabrication of Main Sewer Pipes in Houses

Prefabrication of main sewer pipes in houses involves completing relevant pipeline processes in advance in a fixed area or factory, offering advantages such as improved construction efficiency and quality. During the construction process, attention should be paid to issues such as materials, trench excavation, well body and pipeline construction techniques, and backfill control.

Pipeline Prefabrication Modes

• General Pipeline Prefabrication: In a fixed area, processes such as pipeline cutting, beveling, welding, and inspection are completed in advance. This construction method, being carried out in a fixed area, facilitates coordinated control over quality, progress, and management, while also reducing on-site installation workload and enhancing the overall project level.
• Factory-Based Pipeline Prefabrication: One or more pipe sections are assembled and welded according to drawings in a factory and then transported to the site for overall installation. This mode relies on automated production lines and BIM technology to achieve a流水作业 (assembly-line operation) from material cutting to welding, effectively improving construction efficiency and precision while reducing material waste and on-site operational risks.

Issues and Preventive Measures Related to Prefabricated Pipeline Construction

• Material Issues: Strictly inspect incoming bricks and concrete drainage pipes, and prohibit the use of damaged or cracked materials. Prioritize the use of prefabricated reinforced concrete inspection wells to reduce issues related to unstable on-site bricklaying quality.
• Trench Excavation: Before excavation, prepare a specialized trench excavation plan. Deep trenches require expert论证 (review) as per requirements. Determine the slope ratio or support form based on soil conditions, and prohibit close-range stacking along the trench edges. Additionally, set up a drainage system in the trench, such as a sump pit with a submersible pump, to ensure dry trench construction.
• Well Body and Pipeline Construction Techniques: When constructing inspection wells, ensure that the bricks are intact and the mortar is full, with staggered vertical and horizontal joints. Apply plaster to both the inner and outer walls of the well. Seal the connection between the pipe and the well properly, and do not backfill until curing is complete. During pipeline installation, compact the base and ensure the bedding is in place. Recheck the pipeline slope and centerline, ensure proper sealing of bell-and-spigot joints, and conduct a closed-water test after pipeline installation is complete. Backfilling is only allowed after passing the test.
• Backfill Control: After passing the closed-water test, perform layered backfilling symmetrically, and strictly prohibit unilateral backfilling that may squeeze the pipeline. Backfill materials and compaction degrees should comply with municipal drainage specifications, and direct backfilling with large stones is not allowed.