Duplex Stainless Steel Pipe & Tube
We supply duplex stainless steel pipe and tube in 2205 and super duplex 2507. Seamless 2205 pipe & tube run 6–660 mm OD with walls of 1–12 mm, and welded 2205 heat exchanger tube runs 8–88.9 mm OD. Pipe is made to ASTM A790 and tube to ASTM A789.
2205 to UNS S31803/S32205; super duplex 2507 to UNS S32750
Laser cut to length in our own plant, up to 350 mm OD and 9 m
ASTM G48 pitting and A923 tests on request
EN 10204 3.1 mill certificate; 3.2 with third-party witness on request
Why Order Duplex Pipe & Tube From MTS
01
Seamless 2205 and 2507 Pipe & Tube
Seamless 2205 runs 6–660 mm OD with walls of 1–12 mm. Super duplex 2507 comes in sizes such as 25 × 3, 57 × 3, 76 × 3, 108 × 4, 114 × 4 and 219 × 4 mm etc.
02
Test Reports Your Client Will Ask For
Impact tests, A923 Method A or C and G48 Method A are quoted on request. Tell us the tests your spec names at quote stage.
03
Process Pipe and Exchanger Tube in One Grade
A790 seamless pipe for the lines and A789 heat exchanger tube for the coolers, both in 2205, on one order.
04
Processed in Wuxi, Shipped From Three Ports
We process up to 100,000 tons a month and keep 3,000 tons of stainless pipe & tube in stock (out of 80,000 tons in total) in 60,000 m² of warehouse space in Wuxi. Our own cranes load every container. Orders ship from Shanghai, Qingdao or Tianjin.
Twice the Yield Strength, Built for Chlorides
Duplex pipe & tube have a mixed structure, about half ferrite and half austenite. That gives about twice the yield strength of 316L. It also resists chloride pitting and stress corrosion cracking far better.
For seawater, brine, produced water and hot chloride service, duplex often lasts where 316L fails. Its strength also lets you use a thinner wall for the same pressure.
Duplex and Super Duplex Pipe & Tube Grades
Duplex 2205 Pipe & Tube
UNS S31803 / S32205, EN 1.4462. The workhorse grade for most chloride service. PREN about 35.
Super Duplex 2507 Pipe & Tube
UNS S32750, EN 1.4410. Super duplex pipe & tube for seawater and sour service. PREN 41 or higher.
Super Duplex S32760 Pipe & Tube
Duplex with Cu and W added. Often specified for firewater and seawater systems. Quoted on request.
Lean Duplex Pipe & Tube
UNS S32101 / S32304 for water and structural lines. Lower cost than 2205. Quoted on request.
Duplex Heat Exchanger Tube to A789
Welded 2205 tube from 8 to 88.9 mm OD, wall 0.8–1.5 mm, bright annealed and tested length by length. Seamless tube in exact OD × wall. U-bent tube is quoted on request.
Large Welded Duplex Pipe to A928
Fusion welded pipe from plate for large diameters, quoted on request.
Specifications
| Item | Range |
|---|---|
| Grades | S31803/S32205, S32750; S32760, S32101, S32304 on request |
| EN numbers | 1.4462, 1.4410, 1.4501, 1.4162, 1.4362 |
| Pipe | Seamless 2205 OD 6–660 mm, wall 1–12 mm; seamless 2507 OD 25–219 mm; A928 welded pipe on request |
| Tube | Seamless OD 6–660 mm; welded 2205 heat exchanger tube OD 8–88.9 mm, wall 0.8–1.5 mm |
| Length | Seamless 4–12 m (6 m standard); welded tube 6, 9 or 12 m |
| Standards | ASTM A790 / SA790, A928 / SA928, A789 / SA789; EN 10216-5, EN 10217-7; NORSOK M-650 |
| Tests | Hydro or ET; ferrite, impact, A923 and G48 on request |
Specifying Duplex Pipe & Tube for Your Project
A790, A789 or A928?
Here the standard depends on whether you buy pipe or tube, so the two stay apart.
ASTM A790 covers duplex pipe, seamless or welded without filler. It is ordered by NPS and Schedule. You will see “A790 S31803” or “A790 S32750.”
ASTM A789 covers duplex tubing for general and heat exchanger service. It is ordered by exact OD and wall. ASME code jobs write it as SA789 S31803 or SA789 S32205.
ASTM A928 covers fusion welded pipe, usually with filler, for large sizes. It has five classes for weld X-ray and filler use.
Our advice: use A790 for pipe up to 8″ or 10″, A928 above that, and A789 for any tube bundle.
2205, 2507 or S32760?
Start with 2205. It covers brackish water, cooling water, produced water and most chemical service. Most 2205 today is dual certified S31803/S32205. S32205 has tighter Mo and N limits, so it meets both.
Step up to super duplex 2507 (S32750, 1.4410) for warm seawater, high chloride brine or sour gas. S32760 sits at the same level. Many offshore firewater specs name it.
Not sure which you need? Send chloride level, temperature and pH. We will tell you what other buyers use in the same service.
Thinner Wall, Lower Weight
Duplex has about twice the yield strength of 316L. Design codes allow a higher stress, so the same pressure needs a thinner wall.
That can mean Sch 10S duplex in place of Sch 40S 316L. The pipe & tube weigh less, weld faster and need lighter supports. On long lines, this offsets much of the higher price per kilogram. Ask your engineer to recheck the wall before copying a 316L line list.
Welding Duplex on Site
Duplex loses its balance if welded carelessly. Too little heat gives too much ferrite. Too much heat forms brittle phases. Field welds cannot be annealed afterward.
Follow these basics:
- Overalloyed filler, such as 2209 for 2205 and 2594 for 2507.
- Controlled heat input and interpass temperature.
- Nitrogen in the shielding or backing gas.
- Ferrite checks on the root and cap.
Welders qualified on 316L need a separate duplex procedure. Plan it before the material arrives.
When Duplex Is the Wrong Choice
Duplex is not for high temperature. Above about 250–300°C, it becomes brittle over time. Use 310 Stainless Steel Pipe & Tube or other austenitic grades for hot service.
Duplex is also weak below about -50°C, where toughness drops. For cryogenic lines, 304L or 316L is safer.
Frequently Asked Questions
Is ASTM S31803 still accepted on new projects?
Yes. Many specs still list ASTM S31803. Material dual certified S31803/S32205 meets both, so it satisfies either spec. Check that your certificate shows both UNS numbers.
What is 1.4410 super duplex?
1.4410 is the EN number for super duplex 2507, UNS S32750. It is the same steel, named under European standards. EN 10216-5 pipe & tube are marked 1.4410; A790 pipe is marked S32750.
Can duplex pipe & tube be used with 316L fittings?
It can, but the joint takes the weaker material's limits. Most specs require duplex fittings with duplex pipe & tube.
How do I check duplex pipe & tube on site?
Duplex is magnetic, so a magnet cannot tell 2205 from carbon steel. Check the grade and UNS number in the stencil and on the mill certificate. For welds, a ferrite reading on root and cap confirms the weld procedure.
Do you work with duplex pipe suppliers and stockists?
Yes. We supply distributors who stock duplex for local projects. Mixed loads of 2205 and 2507 can ship together. Ask for our current size list.
Why is super duplex so expensive?
It has more chromium, molybdenum, nickel and nitrogen than 2205. It is harder to make and test. Mill runs are fewer, so lead times are longer. Price also depends on size, tests and documents.
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