Stainless Steel 348H — UNS S34809 Technical Reference

Stainless Steel 348H (S34809) is included here as a material reference. Controlled carbon, grain size and delivery condition support elevated-temperature use; grade identity alone does not establish a design temperature.

Scope: Numerical limits below apply only to the named source, product form and condition. They are not measured results, design allowable stresses or guarantees for every product with this UNS. Acceptance follows the purchase order and applicable design/product standards.

1. Selected Chemical Requirements

Basis: ASTM A213/A213M-25, Table 2 (seamless boiler/heat-exchanger tube reference). Values are mass %. This selected-element table does not replace the complete source table and footnotes.

A213 Table 2 note H controls Nb+Ta, with Ta ≤0.10% and Co ≤0.20%. A312 pipe has its own combined-element requirements; check Table 1 and note L separately.

2. Mechanical Requirements and Delivery Condition

Basis: ASTM A213/A213M-25, Table 4. Published room-temperature minima. The source MPa and ksi values are shown separately; do not combine unit systems when assessing an order.

Seamless boiler/heat-exchanger tube requirements only. Elongation depends on specimen geometry and table notes. Pipe and transverse values require separate checks.

3. Designation References

UNS S34809 is the material identifier used here. Cross-system names below are comparison candidates only. EN, JIS and GB/T grades can differ in chemistry, form, condition and testing; substitution requires a technical comparison and project-required approval.

These are recorded designation references, not a certification of equivalence. A dash means no confirmed entry is supplied. A common UNS number or commercial name does not establish branded origin.

4. Fabrication and Service Considerations

Controlled carbon, grain size and delivery condition support elevated-temperature use; grade identity alone does not establish a design temperature.

Austenitic grades can suffer chloride SCC, local corrosion or sensitisation under suitable conditions. Low carbon/stabilisation reduces particular risks without eliminating every thermal-history effect. Compare suitable high-alloy austenitic, duplex and nickel candidates using representative service data.

5. Product Standards and Ordering Basis

A213/A213M covers specified seamless boiler/superheater/heat-exchanger tube; A312/A312M is a pipe specification and A269/A269M is for specified general-service tubing. Confirm that the ordered edition actually covers the UNS, route, size and condition. Alternative EN/GB/JIS delivery requires separate verification.

State grade/UNS, form, route, specification/edition, OD/wall/length, condition, examination and documents. ASME SA/SB acceptance and design-code permission require separate checks. EN 10204 type 3.1 is an inspection document, not independent product approval. Chemical and mechanical tests can use different heat/lot sampling bases.

6. Typical Applications

Elevated-temperature parts meeting the design-code and creep requirements.

These are examples, not a service-envelope approval. Confirm medium, concentration, temperature, pressure, flow/stagnation, deposits, crevices, stress and fabrication condition.

7. Product Enquiries and Related Pages

Forms, sizes, availability and certification are confirmed in the written quotation. Send an enquiry with the actual specification and service requirements.

Reference review: 30 October 2026. Editions identify the sources used; they do not assert that all named editions remain active or that alternative standards have identical requirements.