Quick Summary
The designation K21590 refers to a specific material code in the Korean Industrial Standards (KS) system. It corresponds to a carbon steel pipe suitable for high-temperature service. The most common standard that uses this code is KS D 3561, which covers "Carbon Steel and Alloy Steel Pipes for High Temperature Service."
In practical terms, a pipe marked K21590 is a seamless pipe made from a carbon steel grade designed to maintain strength at elevated temperatures.
1. Specification and Equivalent Standards
The primary standard for K21590 is KS D 3561. This standard is roughly equivalent to other international standards for high-temperature seamless pipes.
| Standard | Designation | Equivalent / Similar Standards |
|---|---|---|
| KS D 3561 | K21590 | ASTM A106 Gr. B (Most Common Equivalent) |
| ASTM A53 Gr. B (Seamless Type) | ||
| DIN 17175 St.35.8 | ||
| JIS G 3454 STPT 370/410 |
Note: While these are functionally similar and often interchangeable for many applications, there can be slight variations in chemical composition, heat treatment, and permissible stresses. Always consult the specific standard's data sheet for critical applications.
2. Material and Chemical Composition
K21590 is a carbon manganese steel. Its key characteristic is a higher manganese content than standard carbon steels (like AISI 1020), which gives it improved strength, especially at high temperatures.
A typical chemical composition range is similar to ASTM A106 Gr. B:
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.30 max |
| Manganese (Mn) | 0.29 - 1.06 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.035 max |
| Silicon (Si) | 0.10 min |
3. Mechanical Properties
The mechanical properties make it suitable for pressure-containing applications. The values below are typical for a pipe in the normalized or hot-finished condition.
| Property | Value |
|---|---|
| Tensile Strength | ≥ 415 MPa (60,000 psi) |
| Yield Strength | ≥ 240 MPa (35,000 psi) |
| Elongation | Varies with wall thickness, but typically ≥ 20% |
4. Key Characteristics and Advantages
Seamless Construction: No longitudinal weld seam, making it stronger and more reliable for high-pressure applications. It eliminates the risk of weld seam failure.
High-Temperature Strength: Formulated to retain a significant portion of its strength at temperatures up to ~450°C (850°F).
Good Weldability and Formability: Can be easily welded, bent, and flanged using standard procedures, making it versatile for fabrication.
Cost-Effective: Provides an excellent balance of performance, durability, and cost for a wide range of industrial applications.
5. Common Applications
K21590 seamless pipes are widely used in systems that transport fluids or gases at high pressures and/or temperatures.
Power Generation: Boiler tubes, superheater tubes, and main steam lines in fossil fuel power plants.
Oil & Gas Refineries: Process piping for crude oil, hydrocarbons, and other process fluids.
Petrochemical Plants: Transfer lines for chemicals at elevated temperatures and pressures.
High-Pressure Pipelines: For transporting steam, air, water, and oil.
How to Identify and Source
When sourcing or verifying this material, you should look for the following markings on the pipe itself or the accompanying Mill Test Certificate (MTC):
Standard: KS D 3561
Grade/Material Code: K21590
Size: Outer Diameter (OD) and Wall Thickness (WT)
Heat Number: For traceability.
Manufacturer's Mark: The mill that produced the pipe.
Conclusion
The K21590 Seamless Steel Pipe is a high-quality, general-purpose pressure pipe standard from Korea. Its properties are very similar to the globally recognized ASTM A106 Gr. B, making it a reliable choice for high-temperature and high-pressure service in power plants, refineries, and other heavy industries. Its seamless nature ensures maximum integrity for demanding applications.
