In our last blog, we took a look at different types of alloy steel for their material properties—in particular, their ability to resist corrosion. However, when you’re deciding which pipe material and grades to select for your next pipe fabrication or construction project, resistance to acids, solvents, or salts is likely to be just one of many factors you need to take into consideration.
In this blog post, we’re going to dive into different types of alloy pipe and evaluate these special alloys for various industrial use cases so you can make sure your projects are on track to provide reliable, safe performance for years.
Understanding Alloy Steel Pipe Materials
There are many different types of alloy that are used in PVF products. Making the right selection depends on comparing the material properties of various steel alloys with your pipeline system’s intended operating environment. While keeping track of all the various types of special alloys can seem daunting, we’re here to make it simple and break them down by their material properties and capabilities.
Chromoly Steel (Chromium/Molybdenum Alloy Steel)
We start off with a low-alloy steel, also known as alloy steel grade 4130, that derives its unique material properties from its high chromium and molybdenum content. This alloy steel pipe material is known for its high tensile strength, excellent heat resistance, and good resistance to corrosion and oxidation. It can withstand temperatures up to 600 degrees Celsius or higher and provides a long, reliable service life for pipe and tubing in harsh, high-pressure environments.
While it boasts strong resistance to wear and thermal fatigue, though, it is susceptible to embrittlement over time at higher temperatures.
Industry Applications:
- Power generation (e.g., boilers, heat exchangers)
- Oil and gas refining
- Petrochemical processing plants
- High-temperature steam lines
Low-Alloy Steel vs. Carbon Steel
Chromoly steel and other low-alloy steels boast useful material properties for pipe and other PVF parts. However, they often come with financial tradeoffs compared to carbon steel pipe and tube, as carbon steel is more cost-effective both in initial material costs and long-term maintenance costs, while also boasting high strength, durability, and easy weldability.
Low-alloy steels, however, are stronger and tougher overall, with enhanced corrosion resistance and performance under high pressures and temperatures—making them more suitable, if a bit more expensive and more difficult to machine, than carbon steel for more demanding industrial applications.
Stainless Steel (304, 316, 317, etc.)
In our previous blog, we explored stainless steel alloys in-depth for their corrosion and acid resistant properties. However, corrosion resistance is not the only desirable property for stainless steel alloys. Stainless steel alloys also have excellent hygienic properties, making them ideal for high-purity pipelines in food and beverage or pharmaceutical processing lines. Stainless steel is also easy to weld, speeding up fabrication and installation processes.
Industry Applications:
- Food and beverage processing
- Pharmaceutical manufacturing
- Water treatment facilities
- Chemical processing
Nickel Alloy Steels (Inconel, Monel, etc.)
Stainless steels with high nickel content boast impressive performance in extreme temperatures and resistance to acids and alkalis as well as oxidation. However, these types of alloy pipe are very expensive compared to other alloys and are difficult to machine and fabricate.
Industry Applications:
- Aerospace industry
- High-temperature chemical processing
- Oil and gas refining (sour gas applications)
- Nuclear power plants
Carbon-Manganese Steel
Compared to other special alloys, carbon-manganese steel is low-cost and offers reliable performance for low-temperature environments, though it has limited resistance to corrosion and higher temperatures.
Industry Applications:
- Water pipelines
- Structural applications in the oil and gas industry
- Shipbuilding and marine structures
Ferritic Stainless Steel (340, 446, etc.)
This alloy steel’s material properties include high thermal conductivity, low thermal expansion, moderate corrosion and oxidation resistance, and strong magnetic properties, especially at high temperatures. However, the tradeoff is that it lacks the toughness of some other high-alloy steels and is more difficult to weld.
Industry Applications:
- Automotive exhaust systems
- Heat exchangers in power plants
- Industrial boilers and furnace components
Austenitic Stainless Steel (904L, 310, etc.)
Boasting the best corrosion resistance of all stainless steels, these special alloys also stay strong in both extreme heat and cryogenic temperatures. While 904L and 310 stainless steel are non-magnetic, unlike 340 or 446, they are easier to weld than ferritic stainless steel. However, they are also very expensive.
Industry Applications:
- Chemical processing and petrochemical industries
- High-temperature furnace and kiln components
- Piping for highly corrosive substances in pharmaceutical manufacturing
Duplex Stainless Steel
What happens when you combine ferritic and austenitic stainless steel alloys? You get duplex steel, which relies on a dual-phase microstructure for improved strength and corrosion resistance. These pipe material grades boast excellent strength and resistance to stress corrosion cracking, crevice corrosion, and pitting. They are lower-cost compared to high-nickel alloys. However, while they offer easy weldability, they are more difficult to fabricate and machine compared to austenitic steel on its own and have limited use at temperatures above 300 degrees Celsius.
Industry Applications:
- Offshore oil and gas exploration
- Chemical process industry
- Desalination plants
- Marine applications
Choose the Right Alloy Steel Pipe Material with American Stainless
With so many options to choose from, selecting the right alloy steel for its material properties and cost-effectiveness isn’t always a simple or obvious choice for your next project. That’s where American Stainless comes in. With our extensive inventory and supply chain mastery, we’re sure to have the types of alloy pipe and tube you need on hand, or at least not far away. Our customer service team boasts vast knowledge of the US Southeast’s leading industries as well and is on standby to provide any help you need in making the right decision.
Reach out to us today for a price quote and discover why fabricators and contractors all across the US Southeast trust us for pipe and tube supply.