Cast iron pipes used in plumbing applications are typically coated with a layer of protective material to prevent corrosion and extend their lifespan. The most common coating used for cast iron pipes is a layer of asphaltic paint or bituminous coating. This coating helps to create a barrier between the cast iron and the surrounding environment, protecting the pipe from rust and corrosion.
The asphaltic or bituminous coating is applied to the exterior surface of the cast iron pipe. It is a black, sticky substance that adheres to the pipe and provides a protective layer. This coating is resistant to moisture and helps to prevent the pipe from coming into direct contact with water, soil, and other corrosive elements.
In addition to the asphaltic or bituminous coating, cast iron pipes may also receive an additional layer of protective coating on the interior surface. This coating is typically a cement mortar lining that helps to protect the pipe from the corrosive effects of the flowing water and prevents the formation of scale and buildup inside the pipe.
These coatings play a crucial role in maintaining the integrity and longevity of cast iron pipes, ensuring they can effectively transport water and wastewater while resisting corrosion over an extended period of time.