Piping Guide for Prefabricated Houses

The piping of prefabricated houses should be standardized in terms of reserved embedment, construction requirements, material connections, position spacing, protection and fixation, special scenarios, and bending intersections, as detailed below:

1. Reserved Embedment in Prefabricated Components
Prefabricated composite slabs require reserved electrical boxes, while prefabricated walls need embedded electrical boxes and pipes. The reserved length of the pipes should connect with the cast-in-place section to ensure subsequent pipeline continuity.

2. Construction Phase and Basic Requirements
Embedded pipes should be installed before concrete pouring and fixed within the formwork or steel reinforcement structure, embedding with the component as it forms. During construction, reserve positions for boxes, lay the pipelines, then connect and seal them for protection to prevent displacement or blockage during pouring.

3. Material and Connection Specifications
Commonly used materials include PVC pipes, SC pipes (welded steel pipes), and JDG pipes (tight-fitting steel pipes). In civil defense areas, SC pipes must be used with threading, and finished waterproof sleeves are recommended for bathroom drainage pipes. SC and JDG pipes must not be butt-welded or sleeve-welded; instead, use dedicated grounding clamps to connect BVR-4MM² yellow-green bicolored wires. The locknut ends of the pipes should be wrapped with tape to prevent concrete blockage.

4. Position and Spacing Requirements

• Piping in Floor Slabs: Pipelines should take the shortest route with minimal bends. The outer diameter should not exceed one-third of the concrete slab thickness, with a minimum distance of ≥15mm from the surface. Parallel spacing between pipes should be ≥25mm, and fire protection electrical pipelines should maintain a net distance of ≥30mm from the building surface.
• Piping in Shear Walls: Reserve positions for boxes, lay the pipelines after installation, then connect and seal them for protection to ensure the pipes are embedded within the structure.

5. Protection and Fixation Measures
The connection between conduits and electrical boxes (or cabinets) should be secure. Use finished adjustable positioning boxes, with the top and bottom ends tied to the main reinforcement with Ф6 short steel bars. Flatten any crushed pipes with pliers and place stones between the bottom and top reinforcement to prevent deformation. All exposed pipe ends should be tightly wrapped and protected with concrete blocks.

6. Handling Special Scenarios

• Crossing Walls/Floor Slabs: Pre-embed steel sleeves with a diameter 2-3 sizes larger than the actual pipe. For crossing exterior basement walls, fabricate rigid waterproof sleeves with a 5-8mm steel plate welded as a waterstop ring; in civil defense areas, pre-embed airtight sleeves with heights matching the drawings.
• Finished Product Protection: Chiseling should not be excessively large, deep, or wide. Chiseling and drilling are strictly prohibited in prefabricated beams, columns, and prestressed floor slabs. Electricians should monitor during concrete pouring to prevent damage to the piping and displacement of boxes or cabinets.

7. Bending Radius and Intersection Handling
The minimum bending radius for pre-embedded pipes in floor slabs should be ≥6D (D is the pipe diameter). Pipes with a diameter <32mm can be cold-bent or hot-bent using a pipe spring, while those ≥32mm should use finished elbows. When laying pipes in the internal bedding layer, minimize intersections; no more than three pipes should intersect at the same point, and the intersection should not excessively raise the top reinforcement.