ASTM A790 S32750 Super Duplex Stainless Steel Pipe
Product Overview
ASTM A790 S32750 pipe is a super duplex stainless steel pipe designed for applications requiring high mechanical strength and resistance to localized corrosion. Also designated as UNS S32750, this grade typically contains approximately 25% chromium, 7% nickel, and 3–4% molybdenum, with nitrogen added to support its corrosion resistance and duplex microstructure.
The combination of austenitic and ferritic phases provides a balance of strength and corrosion resistance. S32750 is commonly specified for demanding environments in offshore engineering, chemical processing, oil and gas production, and seawater-related systems.
ASTM A790/A790M covers seamless and welded ferritic/austenitic stainless steel pipe. Product supply conditions, dimensions, testing requirements, and acceptance criteria should be confirmed against the applicable standard edition and purchase specification.
Technical Specifications
| Item | Description |
|---|---|
| Product Name | Super Duplex Stainless Steel Pipe |
| Material Grade | S32750 |
| UNS | S32750 |
| Standard | ASTM A790/A790M |
| Equivalent Designation | Commonly known as 2507 |
| Material Type | Super Duplex Stainless Steel |
| Product Type | Seamless or Welded Pipe |
| Manufacturing Route | According to ordered product type |
| Size | As per customer requirements |
| Wall Thickness | As per applicable dimensions and schedule |
| Length | Standard or specified length |
| Heat Treatment | Solution annealing, as required by the standard |
| Inspection | Applicable mechanical, dimensional, and nondestructive tests |
| Documentation | Material Test Certificate (MTC), subject to order requirements |
Chemical Composition of UNS S32750
The following table gives typical ASTM A790 S32750 composition limits. Verify the applicable standard edition and material certificate before using these values in a contractual specification.
| Element | Composition (%) |
|---|---|
| Carbon (C) | ≤ 0.030 |
| Manganese (Mn) | ≤ 1.20 |
| Silicon (Si) | ≤ 0.80 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.020 |
| Chromium (Cr) | 24.0–26.0 |
| Nickel (Ni) | 6.0–8.0 |
| Molybdenum (Mo) | 3.0–5.0 |
| Nitrogen (N) | 0.24–0.32 |
| Copper (Cu) | ≤ 0.50 |
Mechanical Properties
Typical minimum mechanical requirements for UNS S32750 pipe under ASTM A790 include the following. Confirm the exact requirements for the ordered product form, dimensions, and applicable edition.
| Property | Requirement |
|---|---|
| Tensile Strength | ≥ 800 MPa |
| Yield Strength (0.2% Offset) | ≥ 550 MPa |
| Elongation | ≥ 15% |
Hardness limits and additional test requirements should be checked against the applicable ASTM A790/A790M edition and purchase order.
Key Characteristics of ASTM A790 S32750 Pipe
S32750 generally offers higher yield strength than common austenitic stainless steel grades such as 304L and 316L. This can be relevant when evaluating pipe wall thickness and structural requirements, although final sizing must follow the applicable design code.
Its chromium, molybdenum, and nitrogen content supports resistance to pitting and crevice corrosion in many chloride-containing environments. Actual performance depends on temperature, chloride concentration, deposits, flow conditions, and other service variables.
The material combines austenitic and ferritic phases. Proper solution heat treatment and control of fabrication conditions are important to preserve the intended microstructure and properties.
S32750 is used in selected offshore, chemical processing, oil and gas, and seawater-related systems where both strength and corrosion resistance are required. It is not universally suitable for every seawater or chemical environment.
Manufacturing Process
The manufacturing route depends on whether seamless or welded pipe is ordered. Typical production and verification steps may include:
Raw material selection and chemical composition verification.
Pipe forming by the applicable seamless or welded process.
Solution heat treatment in accordance with the applicable specification.
Pickling or other agreed surface treatment.
Dimensional inspection and required mechanical testing.
Applicable nondestructive examination and pressure testing.
Final inspection, marking, and preparation of material documentation.
Specific processes and tests should only be listed as available services after confirmation with the manufacturer.
Applications of S32750 Super Duplex Pipe
Oil and Gas: Selected process piping, production systems, and chloride-containing service environments.
Offshore Engineering: Piping systems exposed to demanding marine conditions.
Chemical Processing: Equipment and pipelines handling compatible corrosive process media.
Seawater Systems: Selected seawater handling and desalination applications, subject to corrosion assessment.
Pulp and Paper: Selected process environments where the material's corrosion resistance is appropriate.
Material selection should be based on the actual service conditions, applicable design code, and corrosion assessment.
ASTM A790 S32750 vs. S31803 / S32205
| Comparison | S32750 | S31803 / S32205 |
|---|---|---|
| Material Category | Super Duplex | Duplex |
| Chromium Content | Approximately 25% | Approximately 22% |
| Molybdenum Content | Approximately 3–5% | Approximately 3% |
| Nitrogen Content | Approximately 0.24–0.32% | Generally lower |
| Strength | Generally higher | High |
| Localized Corrosion Resistance | Generally higher in comparable chloride environments | Good, depending on grade and conditions |
| Typical Selection | More demanding service conditions | General duplex applications |
Actual performance depends on the precise grade, heat treatment, fabrication quality, and operating environment. The comparison should not replace a project-specific material assessment.
Frequently Asked Questions
It is super duplex stainless steel pipe made to ASTM A790/A790M requirements, using UNS S32750 for applications that may require high strength and resistance to localized corrosion.
S32750 is commonly known as duplex grade 2507. Confirm the UNS designation and product specification when purchasing, rather than relying on a commercial grade name alone.
ASTM A790/A790M covers both seamless and welded ferritic/austenitic stainless steel pipe. Availability depends on the supplier's manufacturing capability, dimensions, and order requirements.
It may be suitable for selected seawater applications, but suitability is not automatic. Temperature, chloride concentration, crevice conditions, deposits, flow, and cleaning practices can affect corrosion performance.
S32750 is a super duplex grade generally offering higher alloy content, strength, and localized corrosion resistance than S32205. The appropriate grade depends on the design requirements and service environment.
Depending on the order and supplier capability, documentation may include a material test certificate, chemical analysis, mechanical test results, dimensional inspection records, and applicable nondestructive examination reports.
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