Which type of pipe is commonly used for natural gas in residential installations?

Black iron pipe is commonly used for natural gas in residential installations because it is specifically designed to handle the pressures and properties of natural gas. This type of pipe is durable and can withstand high temperatures, making it suitable for the safe transportation of gas. Black iron has a long history of use in gas applications and is known for its reliability and strength.

Other types of pipes, while they may be suitable for various applications, are not ideal for natural gas. Plastic pipe, for instance, is often used for water supply lines but may not be suitable for high-pressure gas lines due to potential degradation over time. Galvanized steel pipe, while it has been used historically for gas, can rust internally, leading to contamination and flow issues. PEX pipe is typically used for plumbing and heating applications but is not approved for use with natural gas. Each of these alternatives has different characteristics that make them unsuitable for natural gas transport in residential settings.