When designing or upgrading a heat exchanger system for high-temperature or corrosive environments, choosing the right stainless steel grade is crucial. 310 and 310S stainless steel pipes are both excellent candidates due to their superior heat and oxidation resistance. However, there are key differences between them that can significantly affect performance, durability, and welding outcomes.
So, which is better for your heat exchanger – 310 or 310S? Let's dive in.
Common standards include ASTM A312 (seamless/welded pipe), ASTM A213 (boiler & heat exchanger tubes), and EN 10216-5.
| Grade | Key Feature |
|---|---|
| 310 | High carbon for intermittent high-temperature use |
| 310S | Low carbon for continuous high-temperature stability |
| STANDARD | WERKSTOFF NR. | UNS | JIS | BS | GOST | AFNOR | EN |
| SS 310 | 1.4841 | S31000 | SUS 310 | 310S24 | 20Ch25N20S2 | - | X15CrNi25-20 |
| SS 310S | 1.4845 | S31008 | SUS 310S | 310S16 | 20Ch23N18 | - | X8CrNi25-21 |
| Element | SS 310 | SS 310S |
| C | 0.015 max | 0.08 max |
| Mn | 2.0 max | 2.0 max |
| Si | 0.15 max | 1.00 max |
| P | 0.020 max | 0.045 max |
| S | 0.015 max | 0.030 max |
| Cr | 24.00 - 26.00 | 24.00 - 26.00 |
| Mo | 0.10 max | 0.75 max |
| Ni | 19.00 - 21.00 | 19.00 - 21.00 |
| Fe | 54.7 min | 53.095 min |
| Element | SS 310/310S |
| Density | 7.9 g/cm3 |
| Melting Point | 1402 °C (2555 °F) |
| Tensile Strength | Psi – 75000 , MPa – 515 |
| Yield Strength (0.2%Offset) | Psi – 30000 , MPa – 205 |
| Elongation |
40 % |
Heat Treatment:
310: Anneal at 1040–1120°C followed by rapid cooling.
310S: Stress relieve at 870–925°C for welded components.
310: Ideal for intermittent high temps (up to 1035°C).
310S: Best for continuous high temps (up to 1150°C).
310S: No post-weld annealing required due to low carbon.
310: Requires post-weld heat treatment to restore corrosion resistance.
310: Lower initial cost for cyclic heating applications.
310S: Higher cost but reduces long-term maintenance in sustained heat.
Fabrication Tips
The answer lies in welding and corrosion resistance.While both 310 and 310S offer similar thermal performance, 310S contains lower carbon, which minimizes the risk of intergranular corrosion in welded areas – a critical factor in heat exchanger fabrication. This makes 310S the preferred choice for pressure-bearing, welded tube sheets, U-bend tubes, and shell-side piping.
At Gnee Steel, we supply high-quality 310/310S stainless steel pipes and tubes with full certification to ASTM A312, A213, EN 10216-5, and offer:
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