Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
ASTM A790: Super Duplex 2507 Pipe
ASTM A790 is the standard specification for seamless and welded ferritic / austenitic stainless steel pipe for general corrosive service. Within A790, super duplex 2507 is registered as UNS S32750. The standard covers seamless and welded pipe across the NPS pipe size range (typically 1/8 NPS to 30 NPS and beyond). The European parallel is EN 10216-5 (seamless) for Werkstoff 1.4410.
TorqBolt supplies A790 UNS S32750 seamless and welded pipe across NPS 1/2 to NPS 24 with mill test certificates that record chemistry, mechanical properties, ferrite content, hydrostatic test, and NDE evidence.
ASTM A790 Scope
A790 covers seamless and welded ferritic / austenitic stainless steel pipe for general corrosive service. The standard governs chemistry, mechanical properties, heat treatment, dimensions, hydrostatic testing, NDE, and corrosion testing. Seamless pipe is hot-extruded or pierced and pilger rolled. Welded pipe is strip-rolled and longitudinally welded, with subsequent solution anneal. Sizes follow ASME B36.19M (stainless pipe schedule).
ASTM A790 Chemistry for UNS S32750
| Element | Min % | Max % |
|---|---|---|
| Carbon (C) | (no min) | 0.030 |
| Chromium (Cr) | 24.0 | 26.0 |
| Nickel (Ni) | 6.0 | 8.0 |
| Molybdenum (Mo) | 3.0 | 5.0 |
| Nitrogen (N) | 0.24 | 0.32 |
| Manganese (Mn) | (no min) | 1.20 |
| Silicon (Si) | (no min) | 0.80 |
| Phosphorus (P) | (no min) | 0.035 |
| Sulfur (S) | (no min) | 0.020 |
| Copper (Cu) | (no min) | 0.50 max, residual, not intentional |
Mechanical Requirements
| Property | Minimum |
|---|---|
| Tensile strength | 800 MPa (116 ksi) |
| Yield strength (0.2 percent) | 550 MPa (80 ksi) |
| Elongation in 50 mm | 15 percent |
| Hardness | 32 HRC max |
Heat Treatment
Solution annealing at 1040 to 1100 degrees Celsius followed by rapid water quench. For welded pipe, the post-weld solution anneal is critical to restore the ferrite / austenite balance disturbed by welding heat input. Heavy-wall pipe (above 25 mm wall) requires particular attention to quench rate at the pipe centre to suppress sigma-phase precipitation.
Required Tests
| Test | Method / Acceptance |
|---|---|
| Chemistry | Per ASTM E1086 family |
| Tensile | ASTM A370 |
| Hardness | HRC or HBW |
| Hydrostatic | To ASTM A999, 1.5 x design pressure typical |
| NDE on welded pipe | 100 percent radiography or UT of weld seam |
| Flattening, flaring, reverse flattening | Per A1016 |
| Ferrite (S2 or S52) | ASTM E562 point count |
| Intermetallic (S57) | ASTM A923 Method A |
| Pitting (S58) | ASTM G48 Method A, CPT above 35 degrees Celsius |
Dimensions
Pipe sizes follow ASME B36.19M for stainless pipe (NPS designation, wall thickness by schedule: 5S, 10S, 40S, 80S, 160). 2507 pipe is supplied across NPS 1/2 to NPS 24 in standard schedules. For non-standard wall thickness, mill rolling is project-specific.
Applications
- Offshore and FPSO seawater piping (firewater, cooling, ballast)
- Process piping in chloride and H2S service
- Sulphuric acid manufacturing piping
- Phosphoric acid piping
- Desalination feed and brine piping
- Caustic and bleach service piping
- Pulp and paper bleach plant piping
- Subsea pipeline material for short flowline jumpers
Related Standards
- ASTM A789: tube spec (smaller sizes)
- ASTM A479: bar spec
- ASTM A182 F53: forging / flange spec
- ASTM A815: wrought fittings (WP-S32750)
- EN 10216-5: European seamless tube spec for Werkstoff 1.4410
- NORSOK M-630: MDS D57 (seamless pipe)
- ASME B36.19M: stainless pipe dimensional standard
- NACE MR0175 / ISO 15156-3: sour service requirements
ASTM A790 Frequently Asked Questions
What does ASTM A790 cover for UNS S32750?
A790 specifies seamless and welded super duplex 2507 pipe for general corrosive service in solution-annealed and water-quenched condition. Pipe sizes follow ASME B36.19M, supplied across NPS 1/2 to NPS 24 in standard schedules.
What is the difference between A790 and A789?
A790 covers pipe (dimensioned by NPS and schedule); A789 covers tube (dimensioned by OD and wall). Same chemistry (UNS S32750), same heat treatment. A790 is the production pipe spec; A789 is the heat exchanger and instrument tube spec.
What is the heat treatment for A790 welded pipe?
Solution annealing at 1040 to 1100 degrees Celsius followed by rapid water quench, performed after welding. The post-weld anneal restores the ferrite / austenite balance disturbed by welding heat input. As-welded pipe is only admissible when WPS qualification proves balanced microstructure.
What yield strength does A790 require for 2507?
Yield 550 MPa (80 ksi) minimum, tensile 800 MPa (116 ksi) minimum, elongation 15 percent minimum. Hardness 32 HRC max, tightened to 28 HRC max for sour service per NACE MR0175.
What NDE is required on A790 welded pipe?
100 percent radiography or ultrasonic examination of the weld seam, plus hydrostatic test at 1.5 times design pressure. Eddy current is acceptable for thin-wall pipe per A1016. Project specifications often add supplementary NDE on the body.
Does A790 cover pipe for sour service?
Yes, when supplemented with NACE MR0175 / ISO 15156-3 requirements: 28 HRC max, 35 to 65 percent ferrite, qualified WPS for welded pipe. NORSOK M-630 D57 layers further requirements for Norwegian Continental Shelf supply.
Satisfaction Survey
