1. **What material is S355 pipe?**
S355 pipe is made from **S355 structural steel**, a non-alloy European standard steel grade defined in EN 10025. It is commonly used in construction and engineering applications due to its good weldability, toughness, and strength. The "S" denotes structural steel, and "355" refers to its minimum yield strength of **355 MPa** (Megapascals).
2. **What does S355 steel mean?**
S355 steel is a **carbon-manganese structural steel** with a minimum yield strength of 355 MPa. It is designed for load-bearing structures like buildings, bridges, and machinery. The steel may include variants such as S355JR, S355J0, or S355J2, which indicate differing impact toughness levels at low temperatures (e.g., 27 Joules at -20°C, 0°C, or -30°C).
3. **What is the ASTM equivalent of S355 steel?**
The closest ASTM equivalents to S355 steel are **ASTM A36** (general structural steel) and **ASTM A572 Grade 50** (high-strength low-alloy steel). While A36 has a lower yield strength (~250 MPa), A572 Grade 50 matches S355 in yield strength (345 MPa) and is often used in similar applications. However, exact equivalence depends on specific mechanical and chemical requirements.
4. **What type of steel is pipe?**
Steel pipes can be made from various types of steel, including:
- **Carbon steel** (e.g., ASTM A53, A106) for general-purpose use.
- **Alloy steel** (e.g., ASTM A335) for high-temperature or pressure applications.
- **Stainless steel** (e.g., ASTM A312) for corrosion resistance.
- **High-strength low-alloy (HSLA) steel** for demanding structural or pipeline uses.
5. **What steel pipe is the strongest?**
The strongest steel pipes are typically made from **high-grade alloy steels** or **quenched and tempered steels**, such as:
- **ASTM A514** (yield strength up to 690 MPa).
- **API 5L X80/X100** (yield strengths of 550–690 MPa for high-pressure pipelines).
- **Maraging steel** (e.g., Grade 250 or 300, with tensile strengths exceeding 2000 MPa).
Strength depends on the application; for example, pipelines prioritize toughness and weldability, while structural uses focus on yield strength.
