Underground Works: Best Practices and Materials for Subsurface Plumbing

Underground pipework is essential for safely transporting water into households and buildings, but it requires careful planning and material selection due to the challenging conditions below ground. The soil environment can be highly corrosive, and various factors can affect the longevity of underground piping systems.

The Challenges of Underground Installations

Underground pipework faces numerous harsh conditions that can reduce its lifespan:

• Soil Composition: The presence of minerals, toxins, and varying pH levels can be corrosive to pipes and fittings.

• Environmental Factors: Freezing and thawing cycles, vibrations, ground settlement, and surface loading all contribute to wear and tear.

• Weather Exposure: Pipes buried too close to the surface are more susceptible to frost and surface disturbances, leading to potential damage.

Choosing the Right Materials

Copper and its alloys, such as DZR brass and bronze, are excellent choices for underground installations due to their natural corrosion resistance and durability. Here are key considerations when selecting fittings:

1. Copper and Capillary Fittings
   Copper’s inherent resistance to corrosion makes it a strong candidate for underground use, and capillary fittings can be installed as usual without special considerations.

   

   Capillary

   Flowflex Capillary fittings are designed for precision and reliability in copper pipe connections. Featuring a capillary action for secure, leak-free joints, they ensure ease of installation and longevity. Ideal for domestic and commercial applications, these fittings provide a neat, robust, and corrosion-resistant solution for HVAC systems.

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2. Brass Fittings – Use DZR or Bronze
   When using brass fittings, ensure they are made from DZR (Dezincification Resistant) material, which enhances their ability to withstand corrosive environments. Alternatively, bronze fittings are also suitable due to their high resilience, but standard brass should be avoided as it lacks the necessary corrosion resistance.

   Compression

   Flowflex Compression fittings, including Type A, Type B, PEX, and Large Bronze Flange Fittings, offer secure, leak-free connections, easy installation, and durability. They ensure flexibility in plumbing, are corrosion-resistant, and provide robust performance, enhancing the efficiency and reliability of HVAC systems.

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3. Type B Manipulative Compression Fittings
   If using compression fittings, opt for Type B Manipulative fittings, which provide additional strength and are specifically designed for use with soft copper tube (R220). This combination offers the flexibility needed for underground installations and ensures a longer service life.

Installation Depth and Protection

Depth plays a critical role in protecting underground pipework:

• Recommended Depth
  Pipes should be installed between 750mm and 1350mm below the surface. This depth strikes the best balance between protection from frost, vibrations, and surface loadings while maintaining reasonable accessibility for maintenance.

• Avoid Excessive Depth
  Although deeper installations offer more protection, they also increase costs and complicate future inspections or repairs.

Extra Protective Measures: Wrapping and Sheathing

For added protection, wrap or sheath pipes and fittings with suitable materials. This additional layer shields the pipework from corrosive elements in the soil and groundwater, extending the system’s lifespan. However, it’s crucial to ensure that the protective sheathing remains intact during installation; any tears or breaks can allow contaminants to accumulate, significantly shortening the expected life of the pipework.

Conclusion

Selecting the right materials, installing at the correct depth, and applying additional protective measures are essential steps to ensure the long-term performance of underground pipework. By carefully considering these factors, you can safeguard your piping systems against the harsh conditions below ground, ensuring they remain reliable and efficient for years to come.