1. The Short Answer
A 1.7335 Seamless Steel Pipe is a seamless (i.e., without a welded seam) tube made from a specific chromium-molybdenum alloy steel. The number 1.7335 is a DIN/EN material number (German/European standard).
Its most common and equivalent designation is 13CrMo4-5 according to the EN 10216-2 standard.
In simple terms, it's a heat-resistant and pressure-resistant pipe used for high-temperature applications, such as steam boilers, superheaters, and high-pressure piping systems.
2. Detailed Breakdown of the Designation
"1.7335" - The Material Number
This is a systematic number from the European standard (EN).
1. : Indicates it's a steel.
7335: A unique identifier for this specific chemical composition. You can look this number up in a material database to find its exact properties.
"Seamless"
This describes the manufacturing process. The pipe is formed by piercing a solid billet of steel to create a hollow shell, which is then elongated and rolled to the required size. This is in contrast to "welded" pipe, which is formed from a rolled sheet and has a seam.
Advantages: Superior strength, better pressure integrity, more uniform wall thickness, and better performance under high stress and temperature.
3. Key Characteristics and Specifications
Chemical Composition (approx. for 13CrMo4-5 / 1.7335)
This is what gives the steel its properties:
Carbon (C): 0.08 - 0.18% (Provides strength)
Chromium (Cr): 0.70 - 1.15% (Improves corrosion/oxidation resistance and strength at high temperatures)
Molybdenum (Mo): 0.40 - 0.60% (Enhances strength at high temperatures and creep resistance)
Manganese (Mn): 0.40 - 1.00% (Aids in strength and hardenability)
Silicon (Si): 0.10 - 0.35% (A deoxidizer, improves strength)
Mechanical Properties
Properties vary with heat treatment condition and wall thickness, but typical values at room temperature are:
Yield Strength (Rp0.2): Min. 280 - 310 MPa
Tensile Strength (Rm): 460 - 590 MPa
Elongation (A): Min. 20 - 22%
Key Performance Features
Good High-Temperature Strength: Retains its strength at elevated temperatures (typically up to ~550-600°C / 1020-1110°F).
Excellent Creep Resistance: Resists the tendency to slowly deform under mechanical stress at high temperatures over long periods. This is critical for boiler tubes.
Good Weldability: Can be welded with standard techniques, though pre-heating and post-weld heat treatment (PWHT) are often required.
4. Common Equivalent Standards
This material is known by different names in different standards systems. 1.7335 / 13CrMo4-5 is the most common European designation.
| Standard | Equivalent Designation | Similar/Common US Equivalent |
|---|---|---|
| EN 10216-2 | 13CrMo4-5 (the common name) | ASTM A335 P12 |
| DIN 17175 | 13CrMo44 | |
| ISO 9329-1 | 13CrMo4-5 | |
| ASTM | - | A335 Grade P12, A213 T12 |
Note: While A335 P12 is a very close equivalent, there can be slight variations in chemical composition and mechanical properties. They are not always 100% interchangeable without verification.
5. Main Applications
Due to its properties, 1.7335 seamless pipes are used in:
Power Plant Boilers: For superheater and reheater tubes, and main steam lines.
Petrochemical Plants: In high-temperature process piping and heat exchangers.
Oil Refineries: For transfer lines and furnace tubes.
High-Pressure Pipelines: Carrying steam or other hot gases/fluids.
Summary
When you see "1.7335 Seamless Steel Pipe," you are looking at a high-quality, seamless tube made from 13CrMo4-5 alloy steel. It is specifically engineered to withstand high pressure and high temperatures, making it a critical component in the energy and process industries. Its seamless nature ensures maximum reliability in these demanding applications.
