Draft page. The factory document pack for this page is still under review. Values marked “To be confirmed” have not been verified yet.
Duplex 2205 and super duplex 2507 ball valves
Ball valves · Duplex stainless
Duplex 2205 and super duplex 2507 ball valves are used where chlorides cause pitting in 316 stainless steel, such as seawater and offshore service. 2507 has more chromium, molybdenum and nitrogen than 2205, which gives it a higher pitting resistance number (PREN). Forged bodies use ASTM A182 F51 or F53; cast bodies use A995 4A or 5A.
Who makes this valve
We publish one number per API specification, never a factory-by-factory row: a row with its licence set and expiry year would point at a single registry entry. One RFQ is quoted by several panel factories, and each quotation names the manufacturer, its API licence number and where to verify it, so you can check the source before you order. How we check licences
How it compares
| Property | Duplex 2205 | Super duplex 2507 |
|---|---|---|
| UNS | S31803 / S32205 | S32750 |
| Forged (ASTM A182) | F51 / F60 | F53 |
| Cast (ASTM A995) | Grade 4A (CD3MN) | Grade 5A (CE3MN) |
| PREN = Cr + 3.3 Mo + 16 N | About 35 | 40 or higher, the usual definition of super duplex |
| Typical use | Chloride process service, produced water | Seawater, offshore and higher-chloride service |
Specification range
Grades are public ASTM designations. Which grades, sizes and classes the partner factory supplies is confirmed against its datasheet and sample EN 10204 3.1 certificates before this page goes live.
| ASTM grade | Form | Sizes (NPS) | Pressure classes | End connections | Partner factory supplies |
|---|---|---|---|---|---|
| ASTM A182 F51 | Forged duplex 2205 | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A182 F53 | Forged super duplex 2507 | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A182 F55 | Forged super duplex (S32760) | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A995 4A | Cast duplex 2205 | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A995 5A | Cast super duplex 2507 | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
| ASTM A995 6A | Cast super duplex, higher alloy | To be confirmed | To be confirmed | To be confirmed | To be confirmed |
Pressure–temperature rating
ASME B16.34 lists duplex stainless steels in their own material group with a lower maximum temperature than carbon steel, because duplex grades can embrittle with long exposure at elevated temperature. For reference, the table shows group 1.1 Standard Class values at −29 °C to 38 °C; confirm the rating for the exact duplex grade before you order.
| Pressure class | Max. working pressure (bar) | (psi) |
|---|---|---|
| Class 150 | 19.6 | 285 |
| Class 300 | 51.1 | 740 |
| Class 600 | 102.1 | 1,480 |
| Class 900 | 153.2 | 2,220 |
| Class 1500 | 255.3 | 3,705 |
| Class 2500 | 425.5 | 6,170 |
Partner factory P-T curve for this valve: To be confirmed
Duplex 2205 trunnion ball valves in Class 600
Large-bore duplex valves at Class 600 are normally trunnion mounted for the same torque reasons as carbon steel valves. Whether the partner factory supplies F51 or 4A trunnion valves in Class 600, and in which sizes, is still to be confirmed.
F51, F53 and F55: choosing the duplex grade
Forged parts use ASTM A182 F51 or F60 for 2205, F53 for 2507 and F55 for super duplex UNS S32760. Cast parts use ASTM A995: grade 4A for 2205, 5A for 2507 and 6A for a higher-alloy super duplex casting.
The grades are not interchangeable. Higher chromium, molybdenum and nitrogen raise the pitting resistance number and the strength, but also the welding care needed. The purchase order should name the standard and grade, and the material certificate should show the UNS number and the composition, so the PREN can be calculated from it.
Sour service: ISO 15156 and duplex
Duplex stainless steel is popular in sour wells, but it is not automatically acceptable under NACE MR0175 / ISO 15156. ISO 15156-3 sets limits by grade, temperature, H2S partial pressure and chloride content, and it can require a specific heat treatment or restrict the welding procedure.
The RFQ should state the H2S partial pressure, the design temperature and the chloride content. A quotation that only says “sour service”, without those values, cannot be checked against the standard.
Welding, ferrite balance and documents
Duplex properties depend on a balanced ferrite–austenite structure. Welding, heat treatment and hot forming can shift the balance or form intermetallic phases that reduce toughness and corrosion resistance, so the welding procedure and the heat treatment have to be controlled together.
Purchasers commonly ask for a ferrite count and ASTM A923 testing, which covers impact testing, corrosion testing and metallographic examination for detrimental phases. Add the EN 10204 3.1 material certificates and the pressure test record for each serial number.
Datasheet and drawings
Datasheet: To be confirmed
A datasheet, dimension drawing and STEP file will be published here, without factory branding, after the panel factory authorises them. Until then, ask for them in your RFQ.
Prices, lead times and minimum order quantities are quoted per enquiry against the datasheet you send; they are not listed on this page.
Frequently asked questions
- Is 2507 a duplex or super duplex steel?
- 2507 is a super duplex stainless steel. Its PREN is 40 or higher, the threshold normally used to call a duplex grade super duplex.
- What is the difference between 2205 and 2507?
- 2507 has about 25% chromium, 4% molybdenum and more nitrogen, against about 22% chromium and 3% molybdenum in 2205. That raises its pitting resistance and strength, at a higher cost.
- What is the equivalent of super duplex 2507?
- UNS S32750, EN 1.4410. Forged valve parts use ASTM A182 F53 and cast parts use ASTM A995 Grade 5A.
- What material is ASTM A182 F51?
- F51 is the forged designation for duplex stainless steel UNS S31803, the original 2205 composition. F60 covers UNS S32205, a tighter 2205 composition.
- Is duplex stainless steel suitable for sour service?
- Only within the limits of NACE MR0175 / ISO 15156, which depend on the grade, the temperature, the H2S partial pressure and the chloride content. Duplex is often used in sour service, but the grade and the heat treatment have to be checked against the standard for the actual conditions.
Standards cited
- ASTM A182: Forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service.
- ASTM A995: Austenitic-ferritic (duplex) stainless steel castings for pressure-containing parts; grades 4A and 5A are common for valve bodies.
- NACE MR0175 / ISO 15156: Metallic materials for use in H2S-containing environments in oil and gas production: material selection, heat treatment and hardness limits for sour service.
- ASTM A923: Test methods for detecting detrimental intermetallic phases in duplex stainless steels.
- EN 10204: Types of inspection documents, including the 3.1 and 3.2 certificates.
- ASME B16.34: Valves with flanged, threaded and welding ends: pressure–temperature ratings by material group and pressure class. Edition quoted to: ASME B16.34-2025.