Project Description
Super Duplex 25 Chrome Stainless Steel Pipe Structure / Bar – SHUNFU METAL
In the aggressive landscape of offshore oil and gas extraction, standard duplex stainless steels often fail to meet the dual demands of extreme mechanical stress and corrosive volatility. SHUNFU METAL engineers and supplies Super Duplex 25 Chrome (25CRW & 25CRS) pipe and tubing specifically for these hostile environments. We target the gap where standard 22Cr duplex falls short, providing a cold-hardened solution capable of withstanding high-pressure sour service (H2S) and high-chloride seawater injection systems.
Our manufacturing process focuses on delivering grades UNS S32750, S32760, and S39274 with a Pitting Resistance Equivalence (PREN) strictly maintained at ≥40. This is not off-the-shelf piping; this is engineered metallurgy designed for downhole tubing, liners, and subsea flowlines where failure costs millions. As a dedicated manufacturer, SHUNFU METAL controls the entire production chain—from the electric furnace to the final cold drawing—ensuring every joint meets API 5CRA and ISO 13680 specifications.
“The ‘Super’ designation isn’t marketing fluff. It represents a calculated chemical balance—specifically the addition of Nitrogen, Molybdenum, and Tungsten—that pushes the critical pitting temperature and yield strength far beyond conventional austenitic steels.”
Why Choose Super Duplex 25 Chrome?
Operators facing sweet (CO2) and moderately sour (H2S) wells often struggle with material selection. Carbon steel corrodes too quickly, while nickel-based superalloys (like Inconel) drive project costs to unsustainable levels. Super Duplex 25 Chrome sits in the economic and technical “sweet spot.”
The PREN ≥40 Standard:
Resistance to localized corrosion (pitting and crevice corrosion) is non-negotiable in chloride-rich environments. The Pitting Resistance Equivalent Number (PREN) is calculated as:
PREN = %Cr + 3.3(%Mo + 0.5%W) + 16%N.
SHUNFU METAL guarantees a PREN of over 40 for our 25 Chrome series. This provides superior resistance to chloride stress corrosion cracking (SCC) compared to 22Cr Duplex or 316L Stainless.
Cold Hardened for Strength:
We do not just supply annealed pipe. For deep wells requiring high tensile capacity, we utilize cold working processes to elevate yield strengths up to 140 ksi (965 MPa) without sacrificing ductility. This allows for thinner wall thicknesses, reducing total string weight and enabling deeper reach.
Critical Applications in Oilfield & Marine Sectors
Upstream Oil & Gas (OCTG)
Tubing & Liners: Used extensively in sour service wells where H2S partial pressure is ≤ 3.0 psi. The material resists sulfide stress cracking (SSC) at temperatures up to 450°F.
Water Injection: Ideal for seawater injection wells where high oxygen and chloride levels would destroy standard stainless steel.
Midstream & Processing
Heat Exchangers: The high thermal conductivity and corrosion resistance make 25Cr excellent for aggressive fluid cooling systems.
Subsea Flowlines: High strength-to-weight ratio reduces installation costs for umbilical and flowline applications.
Standards, Grades & Product Availability
Global procurement requires strict adherence to international standards. SHUNFU METAL products comply with NACE MR0175 / ISO 15156 for sour service. We supply the following grades and their commercial equivalents:
| UNS Grade | Common Trade Names / Equivalents | DIN / W.Nr. |
|---|---|---|
| UNS S32750 | SAF 2507®, Duplex 2507, F53 | 1.4410 |
| UNS S32760 | ZERON® 100, Z100, F55 | 1.4501 |
| UNS S39274 | DP3W | – |
Product Forms & Dimensions
- Forms: Seamless Pipe, Tubing, Hollow Bar.
- Outer Diameter (OD): Min 2-7/8” (73.02mm) to Max 10-3/4” (273.05mm). Custom large diameter sizes available upon request.
- Length Range: API Range 1 (R1), Range 2 (R2), Range 3 (R3).
Chemical Composition
The precise control of alloying elements is what defines the “Super” capability. Note the high Molybdenum (Mo) and Nitrogen (N) content across all grades, which is critical for pitting resistance. UNS S32760 and S39274 also include Tungsten (W) for enhanced stability.
| UNS | C | Cr | Ni | Fe | Mn | Si | Mo | Cu | W | N |
|---|---|---|---|---|---|---|---|---|---|---|
| S32750 | ≤0.03 | 24-26 | 6-8 | BAL | ≤1.2 | ≤0.8 | 3-4 | – | – | 0.24-0.32 |
| S32760 | ≤0.03 | 24-26 | 6-8 | BAL | ≤1 | ≤1 | 3-4 | 0.5-1 | 0.5-1 | 0.2-0.3 |
| S39274 | ≤0.03 | 24-26 | 6-8 | BAL | ≤1 | ≤0.8 | 2.5-3.5 | 0.2-0.8 | 1.5-2.5 | 0.24-0.32 |
Manufacturing Process: The ShunFu Method
Quality in Super Duplex steel is determined by the purity of the melt and the precision of the heat treatment. Our process ensures the elimination of detrimental intermetallic phases (like Sigma phase) which can embrittle the material.
- STEP 1 Steel Making: We utilize Electric Furnace melting followed by Vacuum Oxygen Decarburization (VOD) or Argon Oxygen Decarburization (AOD). This refining step is crucial for controlling Nitrogen levels and reducing Sulfur inclusions to ≤0.01%, ensuring superior toughness.
- STEP 2 Pipe Making: Seamless tubes are manufactured via hot extrusion or rotary piercing.
- STEP 3 Solution Annealing: The material is heated to temperatures above 1100°C and rapidly quenched. This restores the 50/50 austenite-ferrite balance and dissolves any precipitates.
- STEP 4 Cold Working: To achieve the high strength grades (110 ksi, 125 ksi, 140 ksi), the pipe undergoes controlled cold drawing. This increases mechanical strength without requiring further heat treatment.
Mechanical Properties (API 5CRA / ISO 13680)
We supply Group 2, Category 25-7-4 materials in various strength levels. The selection of grade depends heavily on the downhole pressure and the sour service limitations defined by NACE MR0175.
| Grade | Yield Strength (ksi) Min-Max | Tensile Strength (ksi) Min | Elongation (%) Min | Hardness (HRC) Max | NACE MR0175 Limits |
|---|---|---|---|---|---|
| 80 (Annealed) | 80 – 105 | 110 | 20 | 28 | H2S ≤ 3.0 psi, Temp ≤ 450°F |
| 90 | 90 – 105 | 115 | 20 | 30 | – |
| 110 (Cold-Worked) | 110 – 140 | 125 | 12 | 36 | H2S ≤ 3.0 psi, Cl ≤ 120g/l |
| 125 | 125 – 145 | 130 | 10 | 36 | – |
| 140 | 140 – 160 | 145 | 9 | 38 | Not recommended for sour service |
*Note: Non-standard mechanical properties can be customized. Contact SHUNFU METAL for technical consultation.
Physical Properties
| Property | Unit | 70°F | 200°F | 400°F |
|---|---|---|---|---|
| Density | lbs/in³ | 0.28 | – | – |
| Thermal Expansion | X10⁻⁶/°F | 7.5 | 7.5 | 7.5 |
| Elastic Modulus | psi x 10⁶ | 29 | 28.2 | 27 |
| Poisson Ratio | – | 0.24 | 0.24 | 0.24 |
| Thermal Conductivity | Btu/ft h °F | 8 | 9 | 10 |
Value-Added Processing Services
SHUNFU METAL is not just a stockist; we are a processing center. Super Duplex steel is notoriously difficult to machine due to its high strength and work-hardening rate. Our facility is equipped with heavy-duty CNC machinery specifically tooled for high-alloy steels.
- Deep Hole Boring & Trepanning: Converting solid bars into heavy-wall mechanical tubing.
- Threading: Premium threading services for OCTG connections.
- Surface Finishing: Turning, peeling, and roller burnishing to achieve precise OD/ID tolerances.
Secure Your Supply of Super Duplex 25 Chrome
Don’t compromise on well integrity. Whether you need 110ksi cold-worked tubing for a sour gas project or large diameter pipe for subsea flowlines, SHUNFU METAL has the inventory and the manufacturing capability to deliver.
We are committed to integrate steel resources in china and serve the global steel market. Our company has more than 15 years of experience in steel researching, production, managing and sales. And our team mostly are based on and worked in national famous steel enterprise before. In the aspect of resources and information, we have established cooperative relationship with nearly hundred enterprises, either state-owned or private owned in China.
What’s more, we have built long, deep and close business relationship with dozens of steel company, Sharing and holding equities with several steel enterprises. Because of the close cooperation with steel companies and our pioneering spirit, which can ensure us stay at the top competition, and ensure our customers get what they really want. We provide preffesional one-stop service to the Contractors of follows project:
- Oil and Gas Pipeline Construction
- Onshore and Offshore
- Boiler Manufacturers
- Oil Refining Equipment
- Petroleum and Chemical Plant Construction
- Fire Protection
- Heating & Air Conditioning
Our ability to purchase materials directly from leading mills at the best possible price will give you the competitive edge. This coupled with a skilled workforce dedicated to embracing the demands of the markets we serve. Just give us a call +86-731-89903933.
