When choosing fittings and valves for a system, material matters. Brass has long been a popular choice, but stainless steel offers advantages in strength, durability, and corrosion resistance that can make it a better option for certain applications.
So, when should you choose stainless steel over brass? The answer depends largely on the application and the water conditions.
Both stainless steel and brass are commonly used in plumbing applications, but they have different properties.
Stainless steel is known for its strength, durability, and corrosion resistance. Boshart’s stainless steel fittings are available in different grades, including 304 and 316 stainless steel.
The primary difference between 304 and 316 stainless steel is the addition of molybdenum in 316 stainless steel. Grade 316 contains approximately 2–3% molybdenum, which significantly improves its corrosion resistance and makes it better suited for highly corrosive applications.
Contains approximately:
316 stainless steel contains approximately:
That added molybdenum is especially important when dealing with chloride-containing water because it improves resistance to chloride-related corrosion and pitting.
One of the key concerns with certain brass alloys is dezincification.
Dezincification is a form of corrosion and weakening that occurs when zinc leaches from a brass alloy. This leaves behind a porous, copper-rich structure with reduced mechanical
Brasses containing more than 15% zinc, often referred to as yellow brasses, are susceptible to dezincification and are not suitable for direct burial.
Dezincification can sometimes be identified by a change in colour, with brass changing from its original yellow appearance to a pink, reddish, or brownish colour.
Water conditions play an important role in how quickly dezincification can occur.
Factors that can accelerate zinc leaching include:
Over time, dezincification can contribute to leaking and structural failure. Zinc deposits can also build up downstream within a plumbing system, potentially narrowing the inside diameter of the pipe and reducing water pressure.
If you've ever seen a brass valve or fitting develop a green, crusty coating, you may have wondered whether it is failing.
Not necessarily.
The green coating is called patina and is the result of copper oxidization. Patina should not be confused with dezincification.
Unlike rust on iron, patina generally does not negatively affect the performance of a brass fitting or valve. In fact, it can form a stable, protective barrier that slows further corrosion.
Moisture and corrosive elements can accelerate this natural oxidization process.
For applications where appearance is important, coatings can help. Zinc-plated coatings can help maintain the appearance and performance of brass components. Chrome-plated supply stops are one example.
When it comes to hard water applications, stainless steel is the superior choice.
Hard water contains dissolved minerals, particularly calcium and magnesium, that can build up inside plumbing components over time. While both materials can be used in plumbing systems, stainless steel is less prone to corrosion and mineral buildup than brass, making it better suited for hard water environments.
Brass can be more vulnerable to the effects of hard water, including mineral scaling and, under certain water conditions, dezincification. As these minerals accumulate, they can create more than just an appearance issue—they can interfere with the performance and operation of valves and fittings.
In brass valves, scale can build up around internal components and moving parts, potentially causing:
Stainless steel offers a clear advantage in these conditions. Its greater resistance to corrosion and mineral deposits makes it a more durable, reliable choice for plumbing systems exposed to hard water.
When durability is a priority, stainless steel has a significant advantage.
Stainless steel fittings and valves are significantly stronger and more durable than brass. Another benefit is it's resistance to cracking. Stainless steel fittings are less likely to crack than brass fittings when exposed to freezing conditions.
For installations where durability and long-term performance are important considerations, stainless steel can be an excellent choice.
If hard water is a concern, stainless steel is the material to consider for long-term performance and durability.
There isn't one material that is the right choice for every application.
When selecting between stainless steel and brass, consider the water chemistry, temperature, chloride levels, expected service conditions, and desired service life.
Stainless steel can be an excellent choice when strength, durability, and corrosion resistance are priorities.
Brass remains a widely used plumbing material, but understanding the water conditions and the specific brass alloy is important for selecting the right product.
The key is to match the material to the application—not simply choose the material you're most familiar with.
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