Types of stainless steel pipe
Applications of stainless steel pipe: Petroleum, chemical, medical, food, light industry, mechanical instruments, and other industrial pipelines and mechanical structural components. .
In addition, when the bending and torsion strength are the same, the weight is lighter, so it is also widely used in manufacturing mechanical parts and engineering structures. It is also used for furniture, kitchenware, etc
Stainless steel is a multi-functional material composed of steel alloy and a small amount of chromium. The addition of chromium improves the corrosion resistance of the material, a feature that gives stainless steel its name.
Because stainless steel requires almost no maintenance, does not rust, and does not affect other metals in contact with it, it is often used in various applications, especially pipe and pipe manufacturing. According to the end use of the pipeline, stainless steel pipes are divided into several categories.
Stainless steel pipes
Pipes and tubes are sometimes difficult to classify, and they are often distinguished according to their functions. In addition to these classifications, stainless steel is also distinguished by type and grade.
For piping and plumbing applications, Type 304 stainless steel is a common choice, because of its high resistance to chemicals and corrosion.
However, Type 304 stainless steel is not compatible with applications ,where the temperature drops between 800 and 1640 degrees Fahrenheit (F), because it is prone to carbide precipitation due to the material’s 0.08% carbon content limit.
Type 304L stainless steel avoids this problem because it has a lower carbon content limit, so it can be welded and higher temperature applications. Other types of stainless steel often contain additives (such as nickel or molybdenum) to enhance the characteristics required in specific applications.
Stainless steel pipes for general corrosion resistance
This general type of steel is suitable for applications that require corrosion resistance beyond other characteristics. Ferritic or martensitic type steel (the steel with the highest chromium content) is heat-treated or annealed.
Austenitic stainless steels (those with high chromium and nickel content) provide higher strength and can be used under the same general conditions as ferritic and martensitic stainless steels.
Stainless steel pressure pipes
Types of stainless steel pressure pipes include seamless and welded pipes, electrofusion welded pipes for high pressure applications, large diameter welded pipes for corrosion or high temperature applications, and seamless austenitic and ferritic stainless steel pipes and welded pipes.
Sanitary stainless steel pipes
Where stainless steel pipes or pipes must come into contact with food and other sensitive products, hygiene is the top priority. Sanitary stainless steel pipes are used for such applications because they have high corrosion resistance, do not fog and are easy to keep clean. For specific applications, different tolerances can be achieved. The grade commonly used for these applications is ASTMA270.
Stainless steel mechanical pipes
Stainless steel mechanical pipes In applications such as cylinders, bearings and other hollow parts, stainless steel mechanical pipes are usually used. In addition to the more traditional round tube cross-section, the tube can also be manipulated to have various cross-sectional shapes, such as square and rectangular. Generally ASTMA 511 and A554 grades are used for mechanical piping applications.
Stainless steel aircraft tubes
In very special aviation applications, chromium-nickel stainless steel is used because of its heat and corrosion resistance. They are used in applications that require hardenable or weldable high-strength aircraft stainless steel pipes, although hardened parts should not be used with certain types of corrosive substances. Low-carbon stainless steel types are a common choice for welded parts.
For applications that require seamless and welded pipes of larger dimensions (1.6 to 125 mm outside diameter), aircraft structural pipes are used; this type of stainless steel is manufactured in accordance with the Aerospace Materials Specification (AMS) or Military Specification (MIL Specification)
Aircraft hydraulic line pipe, another type of aircraft pipe, is used in aerospace applications, such as jet line fuel and hydraulic systems, and tends to be smaller. Usually made of 304 or 304 L stainless steel.
Stainless steel in distribution water
There are millions of miles of pipelines used to transport drinking water around the world. These pipes must be able to resist corrosion by the water itself, soil chemicals and processing chemicals to provide long-life and sanitary quality drinking water. Type 316 (2-3% Mo) stainless steel has been proven to provide the necessary corrosion resistance for most applications, and its cost is competitive with other piping materials. Where additional corrosion protection may be required, such as in coastal installations, duplex stainless steel (3.0-3.5% Mo) can be used to achieve the required hygiene, cost, and service life.
The purpose and application of stainless steel pipes
answer “Why stainless steel?” These and other beneficial properties of molybdenum-containing stainless steel are summarized as follows:
- Excellent corrosion resistance-compared to carbon steel and cast iron or ductile iron, stainless steel is significantly more resistant to water and sterilization Oxidation of the agent. This leads to a longer service life of the pipeline.
- Anti-corrosion: SS does not require internal and external coatings, nor does it require cathodic protection. This reduces the cost of the system and makes stainless steel more compatible with the environment.
- Sanitary material: Due to its very high passivation film stability, SS is basically inert in water. The leaching of alloying elements (Cr and Ni) is within a safe range. Therefore, they provide better drinking water quality.
- Friction coefficient-Compared with cement-lined carbon steel pipe or corroded carbon steel, the friction is smaller, thereby reducing the water pressure loss along the pipeline. This provides an opportunity to reduce the inner diameter of the pipe and save capital costs. This is also the reason for less sediment adhesion and less bacterial colonization. They can also withstand high flow rates.
- Good strength and ductility: SS, especially dual-phase materials, has higher mechanical properties than carbon steel and cast iron pipes. This allows the thickness of the pipe wall to be reduced (without any corrosion margin) and saves investment costs. The best ductility is also important in terms of safety, for example in the event of an earthquake.
- Erosion and corrosion: Duplex stainless steel is more resistant to erosion and corrosion than carbon steel, especially in the presence of sand.
- Easy to manufacture: SS is a highly adaptable material: easy to form, process and weld, coupled with its good ductility, can easily install and modify the pipeline. They also come in a variety of product forms.
- Easy to maintain: With high corrosion resistance and easy solderability, water leakage can be greatly reduced, possibly from 25% to less than 5%, thereby further saving costs. This argument is becoming more and more important due to the increase in water and water treatment costs.
- Excellent durability, because SS resists cracks, cavitation and abrasion corrosion in clean and polluted water and the atmosphere (even pollution). They are cost-effective, can be used for a long time and do not cause environmental pollution. • Recyclable: SS is 100% recyclable, and part of the initial cost can be recovered when recycling.
Stainless Steel Pipe Applications
• Textile Machinery
• Food and Dairy Products Processing
• Power Plants
• Modern Buildings
• Oil and Gas Processing
• Water Treatment Facilities
• Seawater Desalination
• Synthetic Fibers
• Pulp And papermaking
• oil refining and petrochemicals
• energy industry As you can see, stainless steel pipes are widely used and have become the natural choice for heat-resistant and corrosion-resistant metals.
Where are welded stainless steel pipes used?
ERW welded stainless steel pipes are ideal for applications in oil and gas, petrochemical, chemical, pulp and paper, and breweries. Stainless steel pipes are used in the following equipment:
• heat exchangers
• surface condensers
• fluid pipes
• LP/HP heaters