Stainless Steel Pipes
Stainless steel is usually a collective term referring to a different class of two-step process with a maximum carbon content of 2.1%. Steel is made primarily from an alloy of carbon and iron. The feature that makes Stainless steel different is the addition of chromium (Cr) which must be at least 10.5% and other alloying elements such as nickel (Ni). However, the exact components and ratios will vary based on the grade required. Steel corrodes because the iron readily combines with oxygen and other elements in nature to form iron oxide and becomes unstable. But when chromium is added to steel, it reacts to form chromium oxide which protects the surface from rust and creates a corrosion-resistant product.


Stainless Steel Applications

Stainless steel is used in a wide range of applications because of its low-maintenance, oxidation resistant and non -reactive nature. Some of the applications are:
  • Surgical tools and medical equipment
  • Automotive and aerospace
  • Architecture, monuments and sculptures
  • Kitchen sinks, cutlery and cookware
  • Pipes and tubes

Different types of Stainless Steel Piping & Tubing

Sometimes it’s quite difficult to classify pipes and tubes based on their functions. Based on the end-use, we can buy a stainless steel tube and pipe which are categorised as:

Stainless Steel Pressure Pipe: This pipe is made from the combination of chromium and nickel or solid chromium. It is further classified into -
  • Seamless pipe- It can withstand an extreme level of pressure and temperature. Used in a wide variety of different gas and oil applications, mechanical and engineering industries.
  • Welded pipe- Because of its flexibility, low cost and lightweight nature they are generally more preferred in the industries.
  • Electric fusion welded pipe- Used in high-pressure applications
  • Large diameter welded pipe- used in high-temperature applications
Stainless Steel Sanitary Tubing: They are used when stainless steel tubing and piping comes into contact with food and other sensitive products, where sanitation is the main concern. Due to high corrosion resistance and easy to clean properties, it's widely used in such type of applications. The commonly used grade for this application is ASTMA270.
304 stainless steel: As it is highly chemical- and corrosion-resistant, type 304 stainless steel generally used for tubing and piping applications.

Due to the presence of 0.08 per cent of carbon content, it is prone to carbide precipitation, which makes it non- compatible with applications where temperatures fall between 800- and 1640-degrees Fahrenheit(F). This drawback is overcome by Stainless steel type 304L because of its lower carbon content limit and therefore can be used for welding and higher temperature applications.
Stainless Steel Aircraft Tubing: Chromium and nickel type stainless steel is used in highly-specific aircraft applications because of their heat and corrosion-resistance properties. It is mainly found in applications which require high strength and low carbon content.

Why Stainless Steel?

  • Good strength and ductility – In comparison to carbon steel and cast-iron pipes, stainless steel have higher mechanical properties. This property helps in reducing the wall thickness of the pipe and leads to investment cost savings. The good strength and ductility are also beneficial in terms of security, an example in the earthquake.
  • Corrosion protection – In Stainless steel, an internal and external coating is not required. This makes it more cost-efficient and compatible with the environment.
  • Recyclable – Stainless steel can be 100% recycled. Thus, some initial cost is recovered when they are recycled.
  • Coefficient of friction –When compared to cement lined carbon steel pipes or corroded carbon steel, it has lower friction. Hence, it leads to less loss of water pressure along the pipeline. They are also resistant to high flow rates.

Stainless Steel Pipe Applications

  • Fertilizers
  • Breweries
  • Textile Machinery
  • Power Plants
  • Chemicals
  • Pharmaceuticals
  • Construction
  • Water treatment facilities
  • Dairy and Food Processing
  • Stainless Steel in Water Distribution
For the transmission of drinking water, millions of pipelines are used worldwide. In order to provide hygienic delivery of drinking water and long service life, pipelines must offer corrosion resistance to the water itself, treatment chemicals and soil chemistries.

Type 316 (2-3% Mo) stainless steel has been found to the most suitable option for water supply pipelines as they are corrosion resistance and cost-efficient in comparison with other piping material. Duplex Stainless steel (3.0-3.5% Mo) can be used in shoreline installations to achieve the required cost, hygiene, and service life.

Conclusion

Stainless steel pipes are the natural choice when corrosion resistance and low maintenance is required. They are used in a wide range of applications and equipment such as vaporators, automobiles, surface condensers, fluid piping and many more. In many countries, the use of stainless steel is not very common but due to the increase in government calls, switching from copper to stainless steel would be a huge step.