1. The "1.7380" Designation
This number comes from the German DIN (Deutsches Institut für Normung) / European EN material number system. It is the most precise way to identify this steel.
Common Name: The material number 1.7380 corresponds to the steel grade 13CrMo4-5 (according to EN 10216-2).
Similar Standards:
ASTM (USA): A335 P12
DIN (Germany): 13CrMo4-5
ISO: 13CrMo4-5
2. Chemical Composition
The key to 1.7380's performance is its chemical composition, which includes alloying elements that make it stronger at high temperatures than plain carbon steel.
| Element | Typical Composition (%) | Purpose |
|---|---|---|
| Carbon (C) | 0.10 - 0.18 | Provides basic strength and hardness. |
| Chromium (Cr) | 0.70 - 1.10 | Improves corrosion & oxidation resistance, increases strength. |
| Molybdenum (Mo) | 0.40 - 0.60 | Greatly enhances high-temperature strength and creep resistance. |
| Manganese (Mn) | 0.40 - 1.00 | Increases strength and hardenability. |
| Silicon (Si) | 0.10 - 0.35 | A deoxidizer that improves strength. |
The presence of Chromium (Cr) and Molybdenum (Mo) is what classifies this as a low-alloy steel, not a simple carbon steel.
3. Key Properties and Why It's Used for Boilers
Excellent Creep Resistance: This is the most critical property. "Creep" is the slow, permanent deformation of a material under constant stress at high temperatures (e.g., inside a boiler). 1.7380 is designed to resist this deformation over long periods (decades), preventing pipe failure.
Good High-Temperature Strength: It retains its mechanical strength at temperatures where carbon steel would become weak. Its typical operating temperature range is up to about 565°C (1050°F).
Oxidation Resistance: The chromium content provides a protective oxide layer that slows down scaling (oxidation) when exposed to hot steam and flue gases.
Good Weldability and Formability: While it requires pre-heating and specific procedures, it is generally weldable, which is essential for constructing boiler systems.
4. Typical Applications
This steel is specifically engineered for pressure-containing parts in high-temperature service:
Superheater Tubes: Sections of the boiler that heat steam beyond its saturation point.
Reheater Tubes: Re-heat steam after it has passed through a high-pressure turbine.
High-Temperature Steam Pipes: Main steam lines and headers that carry steam from the boiler to the turbine.
Heat Exchangers in demanding thermal plants.
5. Relevant Standards for Pipe Manufacturing
Boiler pipes made from 1.7380 are not generic; they are manufactured to strict international standards that define their chemical, mechanical, and testing requirements.
EN 10216-2: Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties.
ASTM A335 / A335M: Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service. (Grade P12 is the equivalent).
ASTM A213 / A213M: Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes. (Grade T12 is the equivalent for tubes).
Summary
| Feature | Description |
|---|---|
| Common Name | 1.7380, 13CrMo4-5, A335 P12 |
| Material Type | Low-Alloy Steel (Chromium-Molybdenum) |
| Primary Use | High-temperature and high-pressure boiler and pressure vessel components. |
| Key Advantage | Superior creep resistance and strength at temperatures up to ~565°C. |
| Key Elements | Chromium (Cr) for oxidation resistance, Molybdenum (Mo) for strength. |
In conclusion, when you see "1.7380 Carbon Steel Boiler Pipe," it's more accurate to think of it as "1.7380 Creep-Resistant Alloy Steel Boiler Pipe." It is a specialized, high-performance material critical for the safe and efficient operation of modern power generation and industrial boiler systems.
