What is DIN 17175?
DIN 17175 is a German industrial standard that specifies the technical delivery conditions for seamless circular steel tubes designed for high-temperature service. The title of the standard is "Seamless steel tubes for elevated temperatures."
The key takeaway is that these pipes are manufactured to withstand continuous exposure to high pressure and high temperature, such as those found in power stations (fossil fuel and nuclear), industrial boilers, and heat exchangers.
Key Characteristics and Scope
Seamless Construction: The pipes are seamless (without a welded seam), making them inherently stronger and more reliable under high pressure and thermal stress compared to welded pipes.
High-Temperature Focus: The steel grades are specifically chosen and processed to maintain strength and resist creep (slow deformation under constant stress) at elevated temperatures, typically up to 600-650°C.
Pressure Application: They are primarily used for piping systems that carry steam, hot water, or other high-temperature fluids under pressure.
Testing Requirements: The standard mandates rigorous testing, including:
Non-destructive testing (usually ultrasonic testing) to ensure internal and external soundness.
Hydrostatic testing to verify pressure integrity.
Mechanical tests (tensile, hardness) to confirm strength.
Flattening test, ring expanding test, or bend test to check ductility.
Chemical analysis to verify the material composition.
Common Steel Grades in DIN 17175
The standard defines several grades, each with a specific chemical composition and mechanical properties suited for different temperature ranges. The most common grades are the low-alloy heat-resistant steels.
| Grade (Werkstoffnummer) | Common Name / Similar To | Key Characteristics and Typical Use |
|---|---|---|
| St 35.8 / St 35.8 I (1.0305) | Carbon Steel | For lower temperature services. Good formability and weldability. |
| St 35.8 III (1.0309) | Carbon Steel (Killed) | A fully killed (deoxidized) version of St 35.8 for improved uniformity. |
| St 45.8 (1.0405) | Carbon Steel | Higher strength than St 35.8 for moderate temperatures and pressures. |
| 17 Mn 4 (1.0485) | Carbon-Manganese Steel | Higher strength due to Manganese content. Used for high-pressure feedwater lines. |
| 13 CrMo 4-5 (1.7335) | Chromium-Molybdenum Steel | Excellent creep strength at temps up to ~560°C. Widely used in boiler superheaters. |
| 10 CrMo 9-10 (1.7380) | Chromium-Molybdenum Steel | Higher Cr & Mo content for superior high-temperature strength (up to ~590°C). For main steam lines. |
| 14 MoV 6-3 (1.7715) | Molybdenum-Vanadium Steel | Good creep strength, but largely superseded by other grades. |
| X 20 CrMoV 12-1 (1.4922) | High Chromium Steel | A high-strength 12% chromium steel for very high temperatures (up to ~620°C). Used in high-pressure turbine components. |
Note: The numbers in the grade name (e.g., 13 CrMo 4-5) indicate the approximate percentage of alloying elements. The first number (13) is the chromium content x 100, and the second number (4) is the molybdenum content x 100.
Typical Applications
DIN 17175 pipes are fundamental in industries where high-temperature and high-pressure integrity is critical:
Power Generation Plants:
Main steam lines
Boiler superheaters and reheaters
High-pressure feedwater lines
Connecting pipes between boiler and turbine
Petrochemical Industry:
Ethylene cracking furnaces
Process heaters and heat exchangers
Industrial Boilers: For various manufacturing processes.
Nuclear Power Plants: For specific auxiliary systems (primary circuits often use other specialized standards).
Comparison with Other Standards
DIN 17175 is functionally similar to several other international standards. Pipes manufactured to these standards are often considered comparable, though direct substitution requires careful analysis of design conditions.
| Standard | Region | Title / Scope | Common Equivalent Grades |
|---|---|---|---|
| DIN 17175 | Germany | Seamless Tubes for Elevated Temperatures | St 35.8, 13 CrMo 4-5, 10 CrMo 9-10 |
| EN 10216-2 | Europe | Seamless steel tubes for pressure purposes - Part 2 | P235GH, 13CrMo4-5, 10CrMo9-10 |
| ASTM A106 / A335 | USA | Standard Specification for Seamless Carbon/Alloy-Steel Pipe for High-Temperature Service | Grade B (A106), P11, P22 (A335) |
| BS 3602 / BS 3604 | UK | Specification for arc welded and seamless steel pipes for pressure purposes | HFW 430, 622-440 |
Important Note: With the harmonization of European standards, DIN 17175 has been largely superseded by EN 10216-2. However, the old DIN designations are still widely used in industry parlance, and many pipes are dual-certified to both the old DIN and the new EN standard. For example, 13 CrMo 4-5 (DIN 17175) is equivalent to 13CrMo4-5 (EN 10216-2).
Summary
In essence, DIN 17175 defines a family of high-quality seamless steel pipes made from heat-resistant steels. When you see this specification, you can be confident that the pipe is designed for demanding, high-temperature, high-pressure applications where safety and long-term reliability are paramount.
When sourcing or specifying these pipes today, it is crucial to check whether the requirement is for the legacy DIN 17175 or the current European standard EN 10216-2.
