Black Steel Pipe:Black steel pipes are uncoated and made from carbon steel. The name comes from the black oxide scale formed on the surface of the steel pipe following the manufacturing process. Black steel pipes have high heat resistance and are therefore typically used for transporting hot water or gas in residential and commercial buildings. They are also often used for fire sprinkler systems because of their strong resistance to heat. However, black steel pipes are more susceptible to rust and corrosion than galvanized steel pipes, especially when exposed to moisture.
Galvanized Steel Pipe:Galvanized steel pipes are steel pipes that have undergone the process of galvanization, where a protective zinc coating is applied to prevent rusting. The zinc acts as a ‘sacrificial layer’ and will rust before the underlying steel does, thereby greatly extending the life of the pipe in corrosive environments. Galvanized pipes are commonly used in outdoor constructions, like fences, handrails, or for some interior plumbing.

The choice between black steel pipe and galvanized steel pipe depends on the application. Black steel pipes are suitable for carrying gas or hot water in environments where corrosion is not a concern. Galvanized steel pipes, because of their corrosion resistance, are more suitable for carrying water and are used in outdoor or humid environments to prevent rust. Note that galvanized pipes are not recommended for carrying drinking water because the zinc coating may be released into the water over time.

Can galvanized steel pipes be used for indoor plumbing?

Yes, galvanized steel pipes can be, and historically have been, used for indoor plumbing. The zinc coating on galvanized pipes provides a layer of protection against corrosion and rust, which can be beneficial in certain plumbing applications.

However, there are several noteworthy issues to consider:

Zinc and Lead Leaching: Over time, the zinc coating inside galvanized steel pipes can slowly degrade and may leach into the water supply. Before the 1980s, galvanized pipes were sometimes constructed using a small amount of lead. If these pipes corrode, lead might also leach into the water supply, posing a health risk.
Corrosion Over Time: Although galvanized pipes are resistant to corrosion, they are not immune to it. Over a period (often decades), the zinc layer can erode, leading to rust and corrosion that can reduce the pipe’s lifespan and eventually lead to leaks and water damage.
Internal Buildup: Over time, mineral deposits can build up inside galvanized pipes, causing a decrease in water pressure.

Due to these concerns, many modern residential and commercial plumbing systems have transitioned to using copper or plastic (PVC, CPVC, or PEX) pipes, which don’t have the same corrosion issues and are easier to install. However, galvanized steel pipes are still used in some applications where corrosion resistance is a priority and the potential for zinc leaching is not a concern.

It’s always important to check local building and plumbing codes before deciding on the type of pipes to use for a specific application.

What are applications for black steel pipes?

Black steel pipes are versatile and can be used in a variety of applications due to their strength and durability. Some common uses for black steel pipes include:

Transporting Gas and Water: Black steel pipes are often used to transport natural gas and water to residential and commercial buildings. They are well-suited for this purpose due to their resistance to heat and high pressure.
Fire Sprinkler Systems: Because of their heat resistance, black steel pipes are commonly used in fire sprinkler systems. They are able to withstand the high water pressure that is necessary in these systems.
Steam and Air Lines: Black steel pipes are used in steam and compressed air lines because they can withstand high pressure and are resistant to scaling.
Fencing and Railings: Black steel pipes are used for fencing and railings, because they provide a sturdy and durable structure.
Scaffolding: In construction, black steel pipes are often used to create scaffolding for their strength and durability.
HVAC Systems: Black steel pipes can also be used in heating, ventilation, and air conditioning systems, where their resistance to heat can be beneficial.
Oil and Petroleum Industries: Black steel pipes are used in the oil and petroleum industries for moving oil and other liquids.

While black steel pipes have many uses, it’s important to keep in mind that they are more prone to rusting than galvanized pipes, so they may not be the best choice for applications where the pipes will be exposed to moisture or corrosive substances.