Can Super Duplex fittings be used in cryogenic applications?

Yes. Super Duplex fittings have adequate toughness down to -50°C, making them suitable for most LNG and cryogenic service applications. Impact testing is recommended to confirm suitability at low temperatures.

Which grade should I choose: UNS S32750 or UNS S32760?

UNS S32750 is commonly used for offshore and marine piping applications. UNS S32760 is preferred when exposed to highly acidic chloride environments or where additional tungsten is required to enhance resistance against reducing acids.

What is the average lead time for Super Duplex fittings?

Standard sizes ranging from 1/2 inch to 8 inches are generally available from stock. Custom or oversized fittings typically require 4–6 weeks for production, with express delivery options available for urgent projects.

Super Duplex Fittings Manufacturer & Supplier | UNS S32750 & S32760

Q: What is the difference between Duplex and Super Duplex fittings?

Super Duplex fittings (PREN > 40) contain higher chromium (24–26%), molybdenum (3–5%), and nitrogen than standard Duplex 2205 fittings (PREN 30–40). This delivers approximately 30–40% better pitting and crevice corrosion resistance, and ~20% higher mechanical strength. Super Duplex is the material of choice where 2205 has demonstrated SCC or pitting failures. See our Duplex vs Super Duplex guide for a full technical comparison.

Super Duplex Stainless Steel Pipe Fittings

Super Duplex Stainless Steel Pipe Fittings are applied in high-chloride and corrosive conditions, where the exceptional strength and resistance to pitting and crevice corrosion conditions are needed. Solitaire Overseas is a manufacturer and supplier of Super Duplex, grades in common (UNS S32750 2507), UNS S32760, which are applied in offshore, seawater, chemical and process piping work. Our fittings are engineered to provide redistribution of flow, alteration of line direction/size and to join piping equipment with dependable service operation under severe service conditions. We also produce Super Duplex fittings like elbows, tees, reducers and couplings in the right tolerances so that they are simple to install and have a long service life. The solution heat treatment (usually 1040-1120degC) and rapid quenching (air/water) of material (where necessary) is done to maintain the appropriate phase balance and corrosion behavior. Super duplex stainless steels are very strong and resistant to oxidation but long exposure to high temperature may compromise toughness (e.g. 475degC embrittled in duplex grades). This is one of the reasons why Super Duplex components are typically designed to operate within recommended temperature ranges, and appropriate support and controlled forming/heat treatment procedures are necessary in the manufacture.

We provide a full variety of Super Duplex fitting types of various industrial layouts; 90deg and 45deg elbows, equal and reducing tees, concentric and eccentric reducers, caps, couplings, crosses and stub ends to fit lap joint configurations. All fittings are tested and supplied in accordance with the applicable international standards including, but not limited to, ASME B16.9 buttweld fittings, ASME B16.11 forged threaded fittings and socket weld fittings where applicable and, where indicated, MSS SP-43. We have Super Duplex pipe fittings in grade UNS S32750 and S32760 with buttweld, threaded, or socket weld end connections to suit various project needs. As required, Mill Test Certificates (MTC) complying with EN 10204 3.1 may be issued, which fully satisfies material traceability and compliance certification of critical applications within oil and gas, petrochemical, desalination and marine engineering sectors where certification of material is necessary to approve a project and to ensure operational safety.

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Super Duplex steel grades, Which one to use on your project?
Super Duplex Pipe Fittings - Standard Requirements
The Overall Composition of the Chemical
Complete Range of Super Duplex Flange Types
The reasons that Super Duplex does better than regular Stainless Steel
UNS S32750 Vs. UNS S32760 - Technical Comparison
Critical Applications for Super Duplex Pipe Fittings
Certified Super Duplex Materials - 3rd Party Assured
Super Duplex Pipe Fittings- Expert Answers
FAQs About Stainless Steel 304 Tubes

Super Duplex steel grades, Which one to use on your project?

The pipe fittings in super duplex stainless steel are not a single material they are a family of ultra-high-performance alloys with Pitting Resistance Equivalent Number (PREN) of over 40. The choice between UNS S32750 and UNS S32760 is determined by your needs and conditions of specific corrosive environment and the mechanical properties.

UNS S32750 (F53 / 2507)

PREN: 40-43

Best Used: General offshore, moderate chloride and high strength piping systems.

Main Benefit: Economical high performance standard in the majority of marine applications and process.

Explore S32750 Fittings →

UNS S32760 (F55 / Zeron 100)

PREN: 40-45+

Best In: Udimet W/Cu: best in extreme chlorides, acidic media, and sour service applications that need W/Cu improvement.

Important Benefit: Tungsten and copper additions are the best anti-corrosion additives.

Explore S32760 Fittings →

Not Sure Which Grade? Send them your application information to our metallurgical team and we will suggest the best super duplex specification to use in your operating environment. Contact Engineering Team

Super Duplex Fittings — Standard Specifications

Parameter	Specification
Standards	ASTM A182, A815 / ASME B16.9, B16.11, B16.28, MSS SP-43, MSS SP-83, MSS SP-95
Grades Covered	UNS S32750 (F53 / 2507), UNS S32760 (F55 / Zeron 100)
Werkstoff Nr.	1.4410 (S32750), 1.4501 (S32760)
Size Range	Seamless: ½" to 24" NB \| Welded: 24" to 96" NB
Connection Types	Butt Weld (BW), Socket Weld (SW), Threaded (NPT/BSP), Flanged Ends, Beveled Ends
Pressure Classes	Sch 5 to XXS (BW) \| 3000#, 6000#, 9000# (Forged SW/Threaded)
Temperature Range	-50°C to +300°C (-58°F to +572°F)
PREN Value	≥ 40 (Superior pitting resistance vs duplex 2205 at 30–40)
Manufacturing Process	Push, Forge, Press, Cast (Seamless & Welded)
Bending Techniques	Mandrel Bending, Hot Induction Bending, Roll Bending, Rotary Draw Bending
Third Party Inspection	SGS, DNV, TUV, LLOYDS, BV, IRS, PDIL

Chemical Composition of Super Duplex Stainless Steel Fittings

Element	UNS S32750 (%)	UNS S32760 (%)	Role
Chromium	24–26	24–26	Primary corrosion resistance
Nickel	6–8	6–8	Austenite stabilizer
Molybdenum	3–5	3–4	Pitting & crevice resistance
Nitrogen	0.24–0.32	0.20–0.30	Strength + pitting resistance
Tungsten	—	0.5–1.0	Resistance to reducing acids (S32760 only)
Copper	—	0.5–1.0	Corrosion in acid environments (S32760 only)
Iron	Balance	Balance	Base metal

Mechanical Properties of ASTM A815 Super Duplex Pipe Fittings

Property	UNS S32750	UNS S32760
Tensile Strength (min)	795 MPa (115 ksi)	750 MPa (109 ksi)
Yield Strength (0.2% offset, min)	550 MPa (80 ksi)	550 MPa (80 ksi)
Elongation in 2" (min)	15%	25%
Hardness (max)	32 HRC / 310 HB	32 HRC / 310 HB
Impact (Charpy V-notch)	≥ 45 J @ -46°C	≥ 45 J @ -46°C

Equivalent Grades of Super Duplex Stainless Steel Fittings

UNS	EN / Werkstoff	Common Name	ASTM Forging	ASTM Pipe
S32750	1.4410	2507 / F53	ASTM A182 F53	ASTM A790
S32760	1.4501	Zeron 100 / F55	ASTM A182 F55	ASTM A790

Dimensional Tolerances for Super Duplex Buttweld Fittings

All Super Duplex buttweld fittings are manufactured to tight dimensional tolerances in accordance with ASME B16.9 and MSS SP-43:

Thickness (T): ±12.5% of nominal wall
Outside Diameter at Ends: ±1.6mm (up to 10") / ±2.4mm (above 10")
Angularity: ±1° maximum (per MSS SP-43)
Overall Length: ±1% or ±0.5mm (whichever is greater)
Center-to-End (Elbows/Tees): Per ASME B16.9 Table 1

The reasons that Super Duplex does better than regular Stainless Steel

🔬 Corrosion Mastery

In aggressive seawater and chloride environments with PREN >40, these fittings allow pitting to be prevented. They are unusually resistant to stress corrosion cracking (SCC) and crevices corrosion at failure points of standard 316L fittings.

💪 Mechanical Superiority

The sensitivity of yield is 550-650 MPa and this is about 2x more than ordinary austenitic stainless steel. This allows the wall schedules to be thinner and the piping systems to be weighted considerably.

💰 Lifecycle Economics

Although the Super Duplex fittings are more expensive to install in the first place, it has a lower maintenance cost because of long life span and less downtime. Components of smaller weight also lower the requirements of structural support.

🌡️ Environmental Versatility

Works effectively in severe PH (acidic and alkaline) and retains its structure over a temperature range of between cryogenic (-50°C) to moderate heat (+300°C).

UNS S32750 Vs. UNS S32760 - Technical Comparison

Property	UNS S32750 (2507 / F53)	UNS S32760 (Zeron 100 / F55)
Chromium (%)	24-26	24-26
Nickel (%)	6-8	6-8
Molybdenum (%)	3-5	3-4
Tungsten (%)	-	0.5-1.0 (Added)
Copper (%)	-	0.5-1.0 (Added)
PREN	40-43	40-45+
Tensile Strength	750-950 MPa	750-1000 MPa
Best Applications	Offshore platforms, heat exchangers	Acidic chloride media, desalination
More Details	View S32750 Specs	View S32760 Specs

Important Observation: It is anticipated that the definite addition of Tungsten (W) and Copper (Cu) in S32760 pipe fittings offers improvements in resistance to reducing acid (i.e. sulfuric and phosphoric acid) in comparison to S32750 which makes it preferable in specific chemical processing applications.

Critical Applications for Super Duplex Pipe Fittings

⚓
Offshore Oil & Gas
Subsea process piping, topside, and risers that are vulnerable to seawater.
🌊
Desalination and Water Treatment
High pressure brine handling systems and Seawater Reverse Osmosis (SWRO) piping.
⚗️
Chemical Processing
Production of chlor-alkali, fertilizer production and acid transport lines.
🚢
Marine Engineering
Blast water systems, fire fighting system and exhaust gas cleaning.
⚡
Power Generation
Flue Gas Desulfurization (FGD) systems as well as geothermal plant piping systems.

Welding & Hot Forming of Super Duplex Stainless Steel Fittings

Welding of Super Duplex fittings requires controlled interpass temperature (<150°C), matched or slightly overalloyed filler metals (ER2594, E2594), and post-weld solution annealing when required. Correct procedure ensures the ferrite/austenite phase ratio is maintained in the 40–60% range to preserve corrosion resistance.

Hot forming of Super Duplex pipe fittings must be conducted in the 1000–1150°C range followed by rapid water or air quench to prevent sigma-phase and chi-phase precipitation. Forming outside this window — particularly the 600–950°C sensitization range — can severely compromise toughness and corrosion properties.

Note: 475°C embrittlement is a risk with extended exposure in the 350–500°C range. Super Duplex components should not be operated in this temperature zone for extended periods.

Related Super Duplex Products

Certified Super Duplex Materials - 3rd Party Assured

Testing Standards

Ferrite content: 40-60% (ASTM E562)
Impact testing: -46°C (ASTM A370)
Corrosion testing: ASTM G48 Method A

Certifications

EN 10204 3.1 / 3.2 MTCs
NACE MR0175 / ISO 15156
NORSOK M-650 Qualified

Documentation

Heat traceability records
PMI (Positive Material Identification) reports
Dimensional inspection reports

Frequently Asked Questions — Super Duplex Fittings

Q1: What is the difference between Duplex and Super Duplex fittings?

Super Duplex fittings (PREN > 40) contain higher chromium (24–26%), molybdenum (3–5%), and nitrogen than standard Duplex 2205 fittings (PREN 30–40). This delivers approximately 30–40% better pitting and crevice corrosion resistance, and ~20% higher mechanical strength. Super Duplex is the material of choice where 2205 has demonstrated SCC or pitting failures. See our Duplex vs Super Duplex guide for a full technical comparison.

Q2: Can Super Duplex fittings be used in cryogenic service?

Yes. Super Duplex Stainless Steel retains adequate impact toughness down to −50°C (−58°F), qualifying it for most LNG and cryogenic applications. Charpy V-notch impact testing at −46°C per ASTM A370 is performed and documented in the MTC.

Q3: Are Super Duplex fittings compatible with 316L stainless steel piping?

Yes, with appropriate precautions. Super Duplex fittings can be welded to 316L or other austenitic stainless steel piping using appropriate transition filler metals. However, this creates a galvanic couple and the dissimilar material weld procedure must be reviewed. It is recommended to use super duplex filler wire (ER2594) and carry out full weld procedure qualification (WPS/PQR) to ASME IX or ISO 15614.

Q4: What is the difference between ASTM A182 and ASTM A815?

ASTM A182 covers forged fittings (socket weld and threaded, pressure class 3000# to 9000#) in Super Duplex grades F53/F55. ASTM A815 covers wrought buttweld fittings (elbows, tees, reducers etc.) for Super Duplex in UNS S32750 and S32760. Both standards require solution annealing and quenching of the final product.

Q5: What is the lead time for Super Duplex fittings?

Solitaire Overseas maintains ready stock of standard ½" to 8" NB sizes for prompt despatch. Custom or oversized orders typically require 4–6 weeks production lead time. Express delivery options are available for emergency project requirements. Contact our sales team for current stock levels and pricing.

Q6: Which certifications are available with Super Duplex fittings?

We provide EN 10204 3.1 MTCs as standard, with 3.2 available on request. Additional certifications include NACE MR0175 / ISO 15156 (sour service), NORSOK M-650 (subsea), and NACE TM-0284 compliance documentation. Third-party inspection by SGS, DNV, TUV, BV, LLOYDS and others can be arranged.

Q7: What thread types are available for threaded Super Duplex fittings?

Solitaire Overseas supplies Super Duplex threaded fittings with the following thread types: NPT (National Pipe Tapered), BSP (British Standard Pipe), BSPT, and socket weld. All threaded fittings conform to ASME B16.11 with pressure ratings of 3000#, 6000#, and 9000#.

REQUEST A QUOTE FOR SUPER DUPLEX FITTINGS

Send your requirements to Solitaire Overseas Enquiry Form or email us with your material grade, size schedule, quantity, and certification requirements.