Seamless stainless steel tubes in heat resistant grade

Seamless stainless steel tubes in heat resistant grade - overview

Seamless stainless steel tubes in heat resistant grade are precision-made, hollow cylindrical products without a longitudinal weld, designed to perform at elevated temperatures. These tubes are used where oxidation, sulfidation or carburisation can occur and where dimensional stability and corrosion resistance at high temperature are required. In plain terms: they are heat-resistant stainless tubes (also called heat-resisting or heat-resistant stainless steel tubes) suitable for furnaces, burners, glass and ceramic processes, and similar high-temperature applications.

What "seamless" and "heat resistant" mean

Seamless means the tube is manufactured without a welded seam (typically by hot rolling, extrusion or rotary piercing), which gives a more uniform structure and better mechanical performance at high temperature compared with many welded tubes. Heat resistant stainless steels are alloys selected for their ability to resist scaling, oxidation, sulfidation or carburisation when exposed to high temperatures.

Typical applications and industries

Seamless heat-resistant stainless tubes are used across a wide range of sectors, from small workshop projects to heavy industrial installations. Typical uses include:

• Furnace tubes and muffle tubes in heat-treatment and annealing furnaces
• Recuperators and burner components
• Thermocouple protection tubes and thermowell liners
• Components in glass production (e.g. ends of glass-blowing pipes) and ceramic firing (baskets, conveyors)
• Pipe hangers, supports and other fittings in boilers and petrochemical plants
• Applications in automotive exhaust systems, power generation, and offshore equipment where high-temperature corrosion resistance is needed

Who buys these tubes?

Typical buyers are furnace and oven manufacturers, heat-treatment shops, glass and ceramics manufacturers, petrochemical and power plant engineers, maintenance and fabrication workshops, and original equipment manufacturers (OEMs) requiring high-temperature resistant components.

Available grades and key properties

Below are the heat-resistant stainless grades commonly supplied as seamless tubes in this category. Where available, equivalent designations are shown for Europe, the USA and local (Polish) PN/DIN notation to help selection.

Stainless steel 1.4841 (Austenitic heat-resistant)

Designation (provided): AISI: 314 / DIN: X15CrNiSi25-21 / PN: H25N20S2.

Key facts from the technical information:

• Type: austenitic, heat-resistant stainless steel.
• Temperature limits: heat resistant up to about 1150 °C. In atmospheres containing fumes and sulfur compounds resistance is retained up to around 1000 °C, depending on contaminant concentrations.
• Typical uses: ends of glass-blowing pipes, baskets for firing porcelain and heavy-duty conveyor parts where continuous high temperatures and resistance to oxidation/carburisation are required.

Stainless steel 1.4845 (Austenitic, often sold as 310S)

Designation (provided): AISI: 310S / DIN: X8CrNi25-21 / PN: H23N18.

Key facts:

• Type: austenitic chrome–nickel heat-resistant steel (approx. 25% Cr, 20% Ni class).
• Excellent resistance to oxidation and sulfidation; good resistance to carburisation.
• Temperature guidance: in air up to about 1100 °C. In sulfur-containing atmospheres it can be used in the range of about 650–1050 °C depending on whether the atmosphere is oxidising or reducing and whether impurities such as sodium or vanadium are present.
• Common applications: furnace tubes, recuperators, muffle tubes in continuous annealing, thermocouple protection tubes, pipe hangers, burners.

Stainless steel 15X25T (ferritic heat-resistant, also shown as 15Cr25Ti / H25T)

Designation (provided): DIN: 15Cr25Ti / PN: H25T. EN equivalent often cited as 1.4749 (stabilised with aluminium in EN grade instead of Ti).

Key facts and usage notes:

• Type: ferritic heat-resistant stainless steel with very good resistance to sulphur-containing gases and good oxidation resistance in air.
• Temperature guidance: can be used up to about 1150 °C, but has relatively low creep strength at the highest temperatures.
• Creep behaviour: 15X25T (H25T) is noted for very high creep elongation (often exceeding 100%) and comparatively low creep resistance. This means the tube will deform slowly under load at elevated temperature - even its own weight can cause significant bending above ~700 °C. Proper support and design for expected creep are essential.
• Advantages: good resistance to oil and ash corrosion and to molten copper, lead and tin; particularly suitable where sulphur gas reduction resistance is required.

Practical guidance for selection

When choosing a seamless heat-resistant stainless tube, consider:

• Operating temperature - match the grade to the maximum continuous temperature (for example, 1.4841 and 15X25T are rated to ~1150 °C, 1.4845/310S to ~1100 °C in air).
• Atmosphere - oxidising, reducing or sulphur-containing atmospheres influence grade choice (1.4845 is a good general-purpose high-temperature austenitic; 15X25T is especially resistant to sulphur gas reduction).
• Mechanical loads and creep - for parts bearing weight at high temperature, prefer grades with higher creep strength or allow for creep deformation in the support design (pay special attention with 15X25T).
• Scale and corrosion products - grades with higher Cr and Ni content offer better oxidation resistance; presence of sodium, vanadium or other contaminants can reduce service temperature or life.

  How we present material designations

  To help you compare and order the correct tubes we use both common names and technical designations: for example, "stainless steel 1.4845 (AISI 310S / DIN X8CrNi25-21)" or "15X25T (15Cr25Ti, PN H25T, ferritic heat-resistant). Using these equivalents makes it easier to match material specifications with engineering drawings and supplier certificates.

  Summary - matching grade to need

  In short:

  • Choose 1.4841 for very high temperature applications and specific glass/ceramic process parts where temperatures up to ~1150 °C are required.
  • Choose 1.4845 (310S) as a robust austenitic option with very good oxidation and sulfidation resistance up to ~1100 °C in air and appropriate performance in sulphur-containing atmospheres depending on conditions.
  • Choose 15X25T (15Cr25Ti / H25T) when outstanding resistance to sulphur gas reduction and oxidation is required, but design for significant creep and deformation at high operating temperatures.

  Need help choosing?

  If you are unsure which grade suits your application, consider the maximum service temperature, whether the atmosphere contains sulphur or other contaminants, and whether the tube will carry significant load at temperature. Contact our technical support with your operating temperature, atmosphere description and mechanical constraints so we can recommend the correct seamless stainless heat-resistant tube for your project.