PVC water supply pipe village water supply construction plan: stress testing and pipeline antifreeze

in the village water supply project, PVC water supply pipe is widely used because of its corrosion resistance, low cost, easy installation and other advantages. However, due to the complex geological conditions, low temperature in winter and other factors, the construction needs to focus on the control of stress testing and pipeline antifreeze links to ensure long-term stable operation of the water supply system. The following technical points, implementation steps and quality control three aspects to explain.

First, stress testing technical specification

1. Preparation before testing

After the installation of the pipeline is completed, the appearance inspection is required to ensure that the interface is not damaged and the bracket is firm. Use clean water for testing, the water temperature is not less than 5 ° C, and the air in the pipeline needs to be completely discharged through the exhaust valve. The length of the test section should not exceed 1km, and the area with a large height difference should be tested in sections.

2. Graded boost operation

- Pre-test stage: Slowly boost to 1.5 times the working pressure (and not less than 0.6MPa), check whether the interface is leaking after 30 minutes of pressure regulation;

- Main test stage: continue to boost to the test pressure (1.5 times the working pressure), pressure drop after 1 hour of pressure regulation shall not exceed 0.05MPa, and then reduce to the working pressure for appearance inspection to ensure no leakage.

3. Special case treatment

If the leakage point is found, it should be immediately reduced pressure drainage, repair after re-test. Winter test need to take pipeline heating measures to prevent the water body from freezing and cracking pipes.

Second, pipeline anti-freezing construction plan

1. Laying depth control

In cold areas, the buried depth of the pipeline should exceed the local frozen soil thickness of more than 0.3m. Determine the permafrost layer data through geological investigation, for example, the buried depth in the Northeast Plain area needs to reach 1.8m, and the North China area is not less than 1.2m.

2. Selection of thermal insulation materials

- Outdoor surface-mounted pipelines are insulated by high-density polyethylene jacket pipes (PEF), with a thickness of 50mm, and the interface is sealed with waterproof tape;

- Paste 50mm thick polyurethane thermal insulation board on the inner wall of the valve well, and lay a gravel cushion at the bottom of the well for drainage.

3. Drainage and antifreeze design

Set a drain valve at the lowest point of the pipeline, and empty the pipeline when it is out of use or repaired in winter. For water meter wells, double-layer well covers + polystyrene foam board thermal insulation are used, and an electric heating device (power 20W/m) is installed inside.

Third, quality control points

1 Material Acceptance

The PVC pipe entering the site needs to provide the factory certificate, and the wall thickness deviation (10%), drop weight impact test (1kg heavy hammer 1m height impact without crack at 0 ℃) and other tests.

2. Construction record

records the stress testing curve, pipeline coordinate elevation, insulation layer thickness and other data in detail to form a hidden engineering acceptance document.

3. Emergency support

Equipped with emergency repair equipment (such as hot melt welding machine, plugging fixture), establish a winter inspection system, measure the temperature of exposed pipes every day, and start temporary heating measures when the ambient temperature is lower than -10 ℃.

Through the scientific implementation of stress testing and anti-freezing programs, the operation risk of PVC pipeline systems can be effectively reduced. The engineering practice shows that after adopting the above technology, the failure rate of the pipeline in winter can be reduced by more than 80%, and the leakage rate can be controlled within 12%, which significantly improves the water supply guarantee capacity of villages and towns.