Rehabilitation of Aging Pipe Networks: Why Are Ductile Iron Pipe Fittings Preferred Over PVC Fittings in Some Scenarios?

Nov. 04, 2025

In the renovation projects of aging pipe networks, the selection of pipe fitting materials directly affects the renovation quality and long-term operation and maintenance costs. Compared with PVC fittings, ductile iron fittings have become the preferred choice in some key scenarios due to their significant advantages in core performance. The technical logic and application considerations behind this can be analyzed from multiple dimensions.

1. Stronger pressure-bearing capacity, adapting to pressure fluctuations in aging pipe networks

Aging pipe networks often have problems of unstable water pressure and sudden local pressure surges.

Ductile iron fittings have much higher tensile strength and pressure resistance than PVC fittings, usually able to withstand working pressures above 1.6MPa, and some models can reach 4.0MPa.

The long-term safe working pressure of PVC fittings is mostly below 1.0MPa. When facing pressure fluctuations in the pipe network, they are prone to cracking or pipe bursting risks, increasing the cost of secondary maintenance.

2. Better impact resistance and damage resistance, adapting to complex construction environments

The renovation of aging pipe networks is mostly carried out in built-up residential areas and under roads, with narrow construction space and possible external impacts.

Ductile iron has good toughness and can withstand slight collisions during construction, extrusion caused by soil settlement, and indirect impacts of ground vehicle loads.

PVC fittings are relatively brittle. During excavation, transportation, or backfilling, once subjected to external impact, they are prone to damage, leading to delays in the renovation project.

3. Longer service life, reducing long-term maintenance costs

One of the core goals of aging pipe network renovation is to reduce the frequency of subsequent maintenance and extend the overall service life of the pipe network.

Ductile iron fittings have excellent corrosion resistance in soil, with a designed service life of 50-100 years, which can match the renovated pipe network system for a long time.

Although PVC fittings are corrosion-resistant, they are prone to aging and embrittlement due to long-term effects of soil temperature changes and ultraviolet rays, with an actual service life usually of 20-30 years, requiring earlier secondary replacement in the future.

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