Stainless steel is steel to which chrome and nickel elements are added with specific percentages. These elements prevent steel corrosion. In this way, it combines with oxygen in the air and forms a thin oxide layer. This very resistant layer prevents the pipe from being oxidized. Corrosion resistance increases with the increase of chromium. Stainless steel has 12-25% chromium. This element increases the penetration depth of hardness. Nickel, which is added at the rate of 1-4%, increases the strength of steel. But it does not have much effect on the hardness of steel. This element also increases the impact resistance of steel. Molybdenum increases the wear resistance of steel and is often added 0.4-0.1%.

Types of Stainless Steel Pipes

AISI is the most common global standard for stainless steel pipes. According this standard, a three-digit number is used for naming. The first number from the left is between 2-6 and indicates the phases and elements in steel. After three digits, the letters L, S, or H are written, which respectively introduce low carbon steel, medium carbon steel, and high carbon steel. In the following, we explain the most common grades of stainless-steel pipes.

Stainless Steel 304

This grade, which has a maximum of 0.08% carbon, can be used for all cases that require high corrosion resistance. It is not recommended to use this stainless-steel pipe in the temperature range of 426-899 degrees Celsius. Because carbide is deposited.

Stainless Steel 316

The difference between this grade and 304 grade is in the amount of molybdenum and nickel. Grade 316 is more expensive and has higher corrosion resistance than 304 stainless steel. In addition, stainless steel 316 is easier to clean.

Stainless Steel 318

This grade has a higher corrosion resistance due to the addition of 2-3% molybdenum. These stainless-steel pipes are used in places where there is acid, salt water and sea water.

Types of Stainless Steel Pipes based on microstructure

Austenitic Stainless Steel (grades 304 and 316)

• non-magnetic
• High resistance to corrosion up to 815 degrees Celsius
• It has a fine-grained structure
• High impact resistance at low temperature

Stainless Steel Ferrite (grades 409, 430 and 439)

• magnetic
• Coarse-grained
• High carbon content
• Low corrosion resistance compared to austenitic stainless steel

Martensitic Stainless Steel (grades 410 and 420)

• High hardness
• Low corrosion resistance compared to austenitic stainless steel

Sediment hardened Stainless Steel

• magnetic
• High strength

Stainless Steel duplex and super duplex

• Austenitic and ferritic