Material Standard
ASTM A815 Download
ASTM A815 / A815M — Wrought Duplex and Ferritic Stainless Steel Piping Fittings
ASTM A815/A815M (latest edition: A815M-23) is the primary specification for wrought ferritic, ferritic-austenitic (duplex), and martensitic stainless steel butt-welding pipe fittings. The ASME counterpart SA-815 is adopted in BPVC Section II Part A. A815 is the duplex companion to ASTM A403 (austenitic SS) — together they cover the full stainless steel fitting range. Products include elbows (LR/SR), tees, reducers, and caps to ASME B16.9 dimensions.
A815 covers three microstructural families: ferritic-austenitic (duplex) — the dominant group, comprising grades with 40–60% ferrite; ferritic — body-centred cubic (BCC) alloys without nickel; and martensitic grades (410, 420). The duplex grades provide approximately twice the yield strength of austenitic grades (ASTM A403) combined with superior resistance to chloride stress corrosion cracking (SCC).
| Grade | UNS No. | Type | PREN | Typical Application |
|---|---|---|---|---|
| WP2304 | S32304 | Lean Duplex | ~26 | Mildly corrosive service, cost-sensitive duplex applications |
| WP2205 (WP31803) | S32205 / S31803 | Standard Duplex | ~35 | Seawater, desalination, chemical processing, offshore |
| WP2507 | S32750 | Super Duplex | ~43 | FGD, highly aggressive chloride media, deep-sea umbilicals |
| WP2101 | S32101 | Lean Duplex (Mn) | ~26 | Structural applications, cost-optimised with Mn replacing Ni |
| WP446 | S44600 | Ferritic | ~23 | High-temperature oxidation resistance, NO₂ environments |
| WP430 | S43000 | Ferritic | ~18 | Automotive, general corrosion-resistant service |
| Grade | C max | Cr | Ni | Mo | N | Others |
|---|---|---|---|---|---|---|
| WP2304 | 0.030 | 21.5–24.5 | 3.0–5.5 | 0.05–0.60 | 0.05–0.20 | — |
| WP2205 | 0.030 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.08–0.20 | — |
| WP2507 | 0.030 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | Cu 0.50 max |
| WP2101 | 0.040 | 19.5–21.5 | 1.35–1.70 | 0.10–0.80 | 0.20–0.25 | Mn 4.0–6.0 |
| WP446 | 0.20 | 23.0–27.0 | — | — | 0.25 max | N+C ≤0.25 |
| Grade | UTS min (MPa) | YS min (MPa) | Elong. min (%) | Hardness max (HBW) |
|---|---|---|---|---|
| WP2304 | 600 | 400 | 25 | 290 |
| WP2205 | 620 | 450 | 25 | 293 |
| WP2507 | 795 | 550 | 15 | 310 |
| WP2101 | 655 | 450 | 30 | 290 |
| WP446 | 483 | 276 | 20 | 217 |
| Grade | Solution Temp (°C) | Cooling | Target Ferrite % |
|---|---|---|---|
| WP2304 | 980–1080 | Water quench | 40–65% |
| WP2205 | 1020–1100 | Water quench (mandatory) | 40–60% |
| WP2507 | 1050–1150 | Water quench (mandatory) | 40–60% |
| WP446 | 760–830 (anneal) | Air cool | N/A (fully ferritic) |
Duplex caution: Do not hold duplex grades in the 600–1000 °C range during cooling — sigma (σ) phase and chi (χ) phase precipitate rapidly, causing embrittlement and dramatic loss of corrosion resistance. Verify per ASTM A923 Practice A (sodium hydroxide etch) and Practice B (ferric chloride corrosion test).
| Test | Requirement |
|---|---|
| Tensile | One test per heat or heat-treatment lot |
| Hardness | Spot check per lot; 100% on WP2507 for critical service |
| Ferrite Content (duplex) | ASTM A923 Practice A — magnetic or metallographic; ferrite ≥ 25% |
| Corrosion Test | ASTM A923 Practice B (ferric chloride) — supplementary when specified |
| Impact Test (Charpy) | ASTM A923 Practice C — ≥ 54 J at –40 °C for WP2205/WP2507 |
| Chemical Analysis | One ladle analysis per heat |
| Visual & Dimensional | 100%; per ASME B16.9 / B16.28 |
| Industry | Grade | Reason |
|---|---|---|
| Seawater / offshore | WP2205, WP2507 | PREN ≥ 35, SCC resistance, high strength (weight saving) |
| Desalination (RO, MSF) | WP2205, WP2507 | Chloride pitting resistance at elevated temperature |
| Flue Gas Desulfurisation (FGD) | WP2507 | PREN > 40 required; sulphur-chloride combined attack |
| Oil & gas (subsea) | WP2205, WP2507 | High pressure, CO₂/H₂S, chloride SCC resistance |
| High-temperature oxidising | WP446 | Good oxidation resistance to 1100 °C, no creep requirement |
| Standard | Description |
|---|---|
| ASTM A789 / ASME SA-789 | Duplex SS seamless and welded tubing (companion tube specification) |
| ASTM A790 / ASME SA-790 | Duplex SS seamless and welded pipe (companion pipe specification) |
| ASTM A182 F51/F53 | Forged duplex SS flanges and fittings |
| ASTM A403 | Wrought austenitic SS butt-welding fittings (companion austenitic spec) |
| ASTM A923 | Detecting detrimental intermetallic phase in duplex stainless steels |
| # | Item | Example |
|---|---|---|
| 1 | Standard | ASTM A815M-23 or ASME SA-815 |
| 2 | Grade | WP2205 or WP2507 |
| 3 | Fitting type & NPS | 90° LR Elbow, NPS 6, Sch 40S |
| 4 | Dimensional standard | ASME B16.9 |
| 5 | Heat treatment | Solution annealed + water quenched (mandatory) |
| 6 | Test requirements | ASTM A923 ferrite check; Charpy –40 °C if required |
| 7 | Certificate | EN 10204 3.1 MTR with full chemical, mechanical, heat treatment record |
HT PIPE supplies ASTM A815 duplex stainless steel fittings in WP2205 and WP2507, NPS ½–48, solution-annealed with EN 10204 3.1 and NACE MR0175 compliance.
Q1: Why is WP2507 harder to weld than WP2205?
WP2507's higher alloy content (Cr 25%, Mo 4%, N 0.28%) narrows the welding process window. Excessive heat input causes sigma-phase precipitation in the HAZ; insufficient heat input produces excess ferrite. AWS D10.18 and NORSOK M-601 set strict heat input limits (0.5–1.5 kJ/mm). Filler metal must be over-alloyed (e.g. ER2509 for 2507 base metal) to compensate for nitrogen loss in the arc.
Q2: Is A815 WP2205 suitable for H₂S sour service?
WP2205 is conditionally permitted for sour service per NACE MR0175/ISO 15156 Part 3, with hardness ≤ 310 HBW and operating temperature ≤ 232 °C. The duplex microstructure is susceptible to hydrogen embrittlement above 232 °C or under high H₂S partial pressures. Confirm with MR0175 Part 3 Table A.3 for exact temperature and H₂S limits before specifying.