Atomic mass unit 47.867

The lifespan of PVC pipe underground can vary based on several factors, including the quality of the pipe, installation conditions, and the environment in which it's placed. Generally, PVC pipes have a projected lifespan of 50 to 100 years when buried underground. This long-lasting durability is attributed to PVC's resistance to corrosion, chemical stability, and its ability to withstand moderate pressures and temperatures. However, it's crucial to ensure the pipes are properly installed, away from sharp rocks or materials that could cause punctures or cracks, and in conditions that meet the pipe's specifications. Moreover, continuous exposure to extremely high pressures or aggressive chemicals can potentially shorten its lifespan.

The term "polypropylene cast iron" appears to be a confusion of materials, as polypropylene and cast iron represent two distinct categories of materials. Polypropylene is a polymer, a type of plastic known for its versatility and used in various applications, from packaging to automotive parts. On the other hand, cast iron is a metal alloy primarily made of iron and carbon, known for its durability and used in applications like cookware and engineering components. There is no such material as "polypropylene cast iron"; these materials belong to different classes: polymers and metals, respectively.