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What Are the Different Types of Alloy Pipe Fittings?

May 14, 2019 Viega
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Alloy pipe fittings offered by Viega come in three main types: carbon steel, stainless steel and copper nickel. In terms of physical properties, each material has unique qualities that make it a good fit for specific applications.

Here’s an intro to these three types of alloy pipe fittings and where they are used.

Carbon Steel

Carbon steel is a commonly used alloy comprised of iron and carbon. Depending on grade, the carbon percentage can be as low as 0.2 percent or as high as 2.1 percent by weight. The higher the carbon percentage, the stronger the material becomes. Yet more carbon also means the alloy pipe fittings are less ductile and have a lower melting point.

This explains why mild carbon steel that contains a smaller percentage of carbon is the most common choice. Tough yet flexible, carbon steel pipe fittings (with the proper sealing elements in place) are suitable for applications like fuel oil, hydronics and natural gas.

Oftentimes, the properties of carbon steel need to be tuned for specific applications. This involves adding other elements to make what the industry refers to as alloy steel. Viega fittings can be pressed onto any of the alloy carbon steels.

Stainless Steel

Next on our list of alloy pipe fittings is stainless steel, a special category of alloy steel. The same alloying element that gives stainless steel its luminous finish is also responsible for its high resistance to corrosion: chromium. To be labeled stainless steel, the material must be comprised of at least 10.5 percent chromium and no more than 1.2 percent carbon by mass.

In terms of grades, stainless steel pipe fittings are divided into multiple segments, of which 304 and 316 are the most common. The former (and most popular option) contains around 18 percent chromium and 8 percent nickel, while the latter uses less chromium and adds in more nickel as well as molybdenum. The added molybdenum in 316, compared to 304, makes it more resistant to corrosive environments, especially those where you are likely to encounter chlorides, bromides, iodides and acids.

304 and 316 stainless steel are used in similar applications — including acids, chemical process lines and potable water lines — but variance in physical properties make these alloy pipe fittings suitable for different environments. Commercial and some industrial environments use 304 stainless steel pipe fittings, whereas 316 stainless steel fittings are used in industrial spaces with more powerful acids and chemicals (e.g., pharmaceutical and medical manufacturing facilities).

Copper Nickel

Copper has a long history of reliability and safety. Well known to contractors, this material is straightforward to cut, bend and join, can be easily recycled and requires little to no maintenance in common applications.

While copper has a natural defense to corrosion, the harsh environments of the sea raise a unique concern. Chloride in seawater eats away at the oxide film meant to protect the metal surfaces of ships. The more time the vessel spends in the water, the more destructive the corrosion becomes and the more profound the impact on its performance.

In these environments, copper nickel pipe fittings are particularly beneficial. Most often an alloy with 90 percent copper and 10 percent nickel (which contributes to its silver color) and a little bit of iron or manganese for strength, copper nickel is highly resistant to seawater corrosion. These alloy pipe fittings are also recognized for their good tensile strength and inherent resistance to biofouling.

At Viega, we make every effort to serve a broad range of industry needs. That’s why we manufacture high-quality metal press fittings in a variety of materials:

  • Viega MegaPress® for carbon steel pipe
  • Viega MegaPress® Stainless and Viega ProPress® Stainless for stainless steel
  • Viega ProPress® for copper
  • Viega MegaPress® CuNi and Viega SeaPress® for copper nickel

To chat with a Viega representative about your project needs, contact us today.

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