What Is ASTM A249 Stainless Steel Tube?
overview
ASTM A249 is the specification for welded austenitic stainless steel tubes used in heat-exchangers, condensers, superheaters, and boilers. It defines chemistry, mechanical properties, dimensional tolerances, and verification tests. A unique feature is the post-weld cold work before final heat treatment, which refines the weld zone and supports reliable tube-sheet expansion and thermal cycling.
What astm A249 standard is
- Product form: Welded austenitic stainless steel tube.
- Core intent: Deliver tubes with stable weld integrity and uniform properties for thermal duty (HX/boiler).
- Process note: The weld must be cold-worked before the final anneal; heavily cold-worked (HCW) welded tubing is available when specified.
- How to order: OD × wall × length (minimum-wall or nominal-wall per spec), grade, condition, tests/docs, and any U-bend requirements.
ASTM A249 specification Requirements
Chemical Composition
| Grade (TP) | C max | Mn | P | S | Si | Cr | Ni (%) | Mb |
| TP304 | 0.08 | 2 | 0.045 | 0.03 | 1 | 18-20 | 8-11 | - |
| TP304L | 0.035 | 2 | 0.045 | 0.03 | 1 | 18-20 | 8-13 | - |
| TP316 | 0.08 | 2 | 0.045 | 0.03 | 1 | 16-18 | 10-14 | 2-3 |
| TP316L | 0.035 | 2 | 0.045 | 0.03 | 1 | 16-18 | 10-14 | 2-3 |
Mechanical Properties
| Grade (TP) | Tensile min (MPa) | Yield min (MPa) | Elongation in 2 in. (min, %) | Rockwell Hardness Number (max) |
| TP304 | 515 | 205 | 35 | B90 |
| TP304L | 485 | 170 | 35 | B90 |
| TP316 | 515 | 205 | 35 | B90 |
| TP316L | 485 | 170 | 35 | B90 |
Permissible Variations in Dimension
| Item | Requirement | Notes for buyers |
| Wall thickness tolerance | ±10% of nominal wall for all tubing sizes. | Use nominal “t” in your drawings; QA accepts ±10% unless your PO tightens it. |
| Weld-area balance | At the longitudinal weld, the wall must not exceed the wall measured 90° away from the weld by more than the greater of: 6% of the specified wall or 0.004 in (0.1 mm). | Controls “weld bulge” so the tube rolls/expands and seals consistently in service. |
| Other dimensions | As per ASTM A1016/A1016M. | Covers OD, cut length, straightness, and related checks. |
Mechanical Tests Required (per ASTM A249)
- Tension (tensile) test: Confirms minimum strength properties.
- Flattening test: Evaluates ductility and weld integrity under flattening.
- Reverse-bend test: Checks weld soundness and ductility through alternating bends.
- Hardness test: Verifies heat-treat condition and consistency.
- Hydrostatic or nondestructive electric test (ECT): One integrity method must be performed to demonstrate soundness.
- Dimensional & visual inspection: OD, wall, length, ovality/straightness, and surface condition per order.
Common Applications
- Shell-and-tube heat exchangers (process and utility)
- Condensers and superheaters
- Boilers and economizers
- HVAC coils and thermal loops
- District energy and power-plant auxiliaries
FAQs
1. How does A249 differ from A213 and A269?
A249 is welded tubing for thermal duty with post-weld cold-work + final anneal.
A213 covers seamless (and welded) tubes for boiler/superheater/HX, often chosen when a seam-free construction is required.
A269 is general/instrumentation tubing for non-sanitary service.
2. What makes A249 suitable for tube-sheet rolling/expansion?
The required cold-work of the weld before the final anneal produces a refined weld zone that supports leak-tight expansion and thermal cycling.
3. Which grades are most common?
Austenitic TP304/TP304L and TP316/TP316L cover most duties; TP321/TP347 are selected for stabilization at elevated temperatures.
4. What documents come with delivery?
Typically, EN 10204 3.1 MTC, dimensional checks, and test certificates (hydro/ECT) as specified. Heat/lot numbers appear on labels.
