ASTM A928 UNS S32750 EFW Super Duplex Pipe
UNS Grade: S32750
Manufacturing Process: Electric Fusion Welded (EFW)
Size Range: 8" NB – 48" NB (up to 120" available upon request)
Outside Diameter: 219.1 – 609.6 mm (up to 3048 mm)
Wall Thickness: Sch 10 – Sch 160 / XXS (6 – 60 mm)
Length: Fixed lengths, multiple lengths, or cut-to-size (up to 12 m)
Pipe Ends: Plain end, beveled, threaded, or in accordance with ASME B16.25 standards
Are you sourcing large-diameter Super Duplex Stainless Steel pipes for high-chloride process systems but facing project delays and high costs associated with seamless pipes? If your engineering team needs a specification-compliant, cost-effective large-diameter 2507 piping solution with verified weld integrity, ASTM A928 UNS S32750 Super Duplex Stainless Steel EFW Pipe offers a potential alternative for demanding corrosive environments.
ASTM A928/A928M covers ferritic-austenitic duplex stainless steel pipes manufactured by electric fusion welding (EFW) using filler metal. Depending on the applicable class and purchase specification, the standard requires specified heat-treatment and testing procedures to ensure the required material properties and corrosion resistance of UNS S32750 (SAF 2507, EN 1.4410). Unlike seamless Super Duplex Stainless Steel pipes, which may have size and availability limitations, A928 UNS S32750 EFW pipes are formed from duplex stainless steel plate, allowing the production of large diameters with controlled wall thickness. Under ASTM A928 Class 1, the weld seam is subject to radiographic examination as specified by the standard. When the applicable construction code and design conditions permit, a weld joint efficiency factor of 1.0 may be used; confirm the governing code requirements and acceptance criteria for the project.
UNS S32750 welded pipe typically achieves a Pitting Resistance Equivalent Number (PREN) of at least 42 and offers excellent resistance to pitting corrosion, crevice corrosion, and chloride-induced stress corrosion cracking. Its specified minimum yield strength is approximately 550 MPa, around twice the typical minimum value for 316L austenitic stainless steel pipe under common product specifications. Controlled solution heat treatment is essential to maintain the required ferrite-austenite phase balance and minimize harmful intermetallic phase precipitation, such as sigma phase, which can reduce toughness and corrosion resistance. These heat-treatment and inspection controls are important quality checkpoints for every production batch.
We supply fully compliant ASTM A928 UNS S32750 EFW super duplex pipe, Class 1 / Class 5 execution as per your project specification. Our typical size range covers NPS 6 up to NPS 24, wall thickness from 6 mm to 30 mm, with custom lengths, beveled ends, plain cut ends and internal grinding of weld roots available. Surface options include pickled & passivated, mechanically cleaned, or custom coated for external marine insulation service.
Are you looking for specific pipe dimensions/wall thickness series or grade requirements (such as Class 1) for a project?
ASTM A928 Super Duplex Pipe Specification
| Item | Detail |
| Standard | ASTM A928 / ASME SA928 |
| UNS Designation | S32750 |
| Common Name | Super Duplex 2507 / SAF 2507 |
| Process | Electric Fusion Welded (EFW) |
| Size Range | 8" NB – 48" NB (up to 120" on request) |
| OD Range | 219.1 – 609.6 mm (up to 3048 mm) |
| Wall Thickness | Sch 10 – Sch 160 / XXS (6 – 60 mm) |
| Length | Single random, double random, or cut-length (up to 12 m) |
| Ends | Plain, beveled, threaded, or per ASME B16.25 |
| NDE | Hydrostatic, RT, MT/PT on weld seam |
| Certifications | EN 10204 3.1/3.2, NACE MR0175, ISO 9001 |
Chemical Composition (wt. %)
| Element | C | Mn | P | S | Si | Cr | Ni | Mo | N | Cu | Fe |
| Max / Range | 0.030 | 1.20 | 0.035 | 0.020 | 0.80 | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | 0.24–0.32 | 0.50 | Bal. |
PREN (Pitting Resistance Equivalent Number): Cr + 3.3Mo + 16N ≥ 40
Mechanical Properties (Solution Annealed)
| Property | Value | Test Standard |
| Tensile Strength (min) | 800 MPa (116 ksi) | ASTM A370 |
| Yield Strength (min) | 550 MPa (80 ksi) | ASTM A370 |
| Elongation (min) | 15 % | ASTM A370 |
| Hardness (max) | 310 HB / 32 HRC | ASTM E10 / E18 |
| Impact Energy (−46 °C, min) | 45 J | ASTM A923 |
| Annealing Range | 1025 – 1125 °C | - |
ASTM A928 UNS S32750 Super Duplex Pipe Tolerance
|
Standard |
Outside Diameter Tolerance(mm) |
Thickness Tolerance |
Length Tolerance (mm) |
|||
|
|
10.3≤D≤48.3 |
+0.4/-0.8 |
10.3≤D≤73 |
+20% / -12.5% |
+6/-0 |
|
|
48.3<D≤114.3 |
±0.80 |
88.9<D≤457 T/D≤5% |
+22.5%/-12.5% |
|||
|
114.3<D≤219.1 |
+1.6/-0.8 |
88.9<D≤457 T/D>5% |
+15%/-12.5% |
|||
|
219.1<D≤457.2 |
+2.4/-0.8 |
D>508 T/D<5% |
+22.5%/-12.5% |
|||
|
D>508 T/D<5% |
+15%/-12.5% |
|||||
Note: The exact tolerance class (D1–D5 for OD, T1–T5 for wall) may be specified by the purchaser in the purchase order. The default per ASTM A999 is D3 / T3 (±0.75% OD, ±10% wall). For EFW pipe, the weld seam reinforcement is permitted up to 3 mm crown above the base plate surface.
Share your NPS, wall, length, class, NDE requirements and destination code today. Our technical team will return a formal quotation, datasheet and test matrix within 24 working hours to support your tender or PO release.
Inspection and Testing
Every pipe length undergoes the mandatory test suite defined in ASTM A928: full heat chemical and product analysis, transverse weld tensile and guided bend tests, Charpy impact testing, ferrite fraction testing (target 40–60% ferrite), 100% weld RT or UT non-destructive examination, full hydrostatic test per ASTM A999, PMI positive material identification and ASTM G48 Method A pitting corrosion testing on representative coupons.
Packaging
For delivery planning: standard stock diameters ship within 10–18 days; custom plate rolling and heat treatment runs follow a scheduled production timeline. Each pipe is individually marked with heat number, grade, ASTM A928 class, NDE batch ID and heat treatment lot, bundled with rust-proof wrapping and custom fumigated wooden saddles for ocean transit to prevent ovality and weld seam damage.
FAQ
Q1: What is the ASTM A928 standard, and how does it differ from ASTM A790?
A: ASTM A928 is a standard specifically for electric-fusion-welded (EFW) duplex stainless steel pipes manufactured with the addition of filler metal (typically used for medium- to large-diameter pipes). In contrast, ASTM A790 covers seamless pipes as well as automatically welded pipes produced without the addition of filler metal.
Q2: What type of filler wire/consumable should be used for ASTM A928 UNS S32750 welded pipes?
A: An over-alloyed filler material, such as AWS A5.9 ER2594 (or 25.10.4.L), is typically used. This filler contains 9%–10% nickel-a higher concentration than the 6%–8% found in the base metal-to compensate for insufficient austenite precipitation in the weld zone during rapid cooling, thereby ensuring the weld possesses adequate corrosion resistance and toughness.
Q3: What do the classifications Class 1 through Class 5 under the ASTM A928 standard signify?
A: These classifications primarily denote the extent of radiographic testing (RT) and the sequence of heat treatment:
Class 1: The pipe undergoes a full solution-annealing heat treatment after welding, and the weld seams are subjected to 100% radiographic testing (this is the most common class used for critical engineering pipelines).
Class 2: The pipe undergoes heat treatment after welding, but 100% radiographic testing is not mandatory (only spot checks are performed).
Class 3 / 4 / 5: These classes feature various combinations of requirements regarding heat treatment stages and whether the welds are single-sided or double-sided.
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