ASTM A790 S32750 Super Duplex Stainless Steel Welded Pipe: Manufacturing Capabilities & Product Specifications

Short Description:

Womic Steel supplies ASTM A790 S32750 (Super Duplex 2507) welded stainless steel pipe for extreme corrosive environments including high-temperature seawater, acidic chlorides, and sour service with high H₂S. S32750 offers minimum yield strength of 550 MPa (79,800 psi) – nearly three times that of 316L – and tensile strength of 795 MPa (115,300 psi). The super duplex microstructure (40-60% austenite / 40-60% ferrite) with high chromium (25%), molybdenum (4%), and nitrogen (0.27%) provides exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking in aggressive chloride and sulfide environments. Manufacturing includes ERW for small diameters and EFW for large diameters, both with full penetration and post-weld solution annealing. Outside diameter from 6.35mm to 1219mm (1/4″ – 48″), wall thickness 0.5mm – 50mm (Schedule 5S to XXS), standard length up to 12m, custom up to 24m. Mill certificate, hydrotest, 100% UT, solution annealed and pickled finish, beveled or plain ends available. Suitable for offshore high-temperature seawater systems, chemical processing (high chloride acids), flue gas desulfurization (FGD), seawater reverse osmosis (SWRO) high-pressure piping, geothermal wells, and marine exhaust scrubbers.

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Product Description

Welded Super Duplex Stainless Steel Pipe Size: Outside Diameter: 6.35mm – 1,219mm (1/4″ – 48″), Wall Thickness: 0.5mm – 50mm (Schedule 5S, 10S, 40S, 80S), Length: 6m – 12m standard, custom lengths up to 24m

Standard & Grade of Welded Super Duplex Pipe: ASTM A790 (pipe) / ASTM A789 (tubing) S32750; also UNS S32750; EN 10217-7 1.4410; Equivalent to Super Duplex 2507

Usage of Welded Super Duplex Pipe: Offshore oil and gas platforms (high-temperature seawater lift pumps, firewater systems, hydraulic lines), chemical processing (high-chloride organic acids, phosphoric acid), flue gas desulfurization (FGD) absorbers and recirculation lines, seawater reverse osmosis (SWRO) high-pressure piping (70-100 bar), geothermal energy production (high chloride, high temperature brines), marine exhaust scrubbers (SOx removal), desalination brine heater tubes, oil and gas subsea umbilicals and control lines, sour service with high H₂S and chlorides

Womic Steel offering high quality & competitive prices of ASTM A790 S32750 welded super duplex stainless steel pipe, ERW super duplex pipe, EFW super duplex tube, high strength corrosion resistant pipe, seawater resistant pipe, NACE MR0175 compliant. Mill certificate EN 10204 3.1/3.2, hydro test, UT, solution annealed, beveled/plain ends, pickled finish available. Factory direct supply for offshore, desalination, chemical, and geothermal projects worldwide.

Womic Steel: Manufacturing Capabilities & Company Strength

Womic Steel Group is a premier manufacturer and global exporter with over 20 years of expertise in producing carbon, stainless, and duplex (including super duplex) steel tubular products. Our specialized super duplex stainless steel welded pipe production facility utilizes multiple advanced welding technologies with extremely tight control of heat input to maintain the required ferrite/austenite balance (40-60%) and to prevent intermetallic phases (sigma, chi, and R-phase):

ERW (Electric Resistance Welding) Line: For diameters from 6.35mm to 610mm (1/4″ – 24″), wall thickness from 0.5mm to 12.7mm. High-frequency welding with very low heat input (≤ 1.2 kJ/mm) and immediate post-weld seam annealing. Ideal for small to medium diameter super duplex pipes.

EFW (Electric Fusion Welding) Line: For diameters from 219mm to 1219mm (8″ – 48″), wall thickness from 4.0mm to 50mm. TIG (GTAW) root pass with SAW fill passes, using nitrogen-rich backing gas (N₂ + Ar) and matching super duplex filler metal (ER2594).

LSAW / SAWL Line for Super Duplex: For diameters from 406mm to 1524mm (16″ – 60″), wall thickness up to 60mm. Double-sided SAW welding with extremely controlled heat input (≤ 1.5 kJ/mm) and interpass temperature ≤ 100°C.

All super duplex stainless steel welded pipes undergo solution annealing (heat treatment) at 1070-1120°C followed by water quenching to restore the balanced austenite-ferrite microstructure, dissolve any intermetallic phases, and optimize corrosion resistance, followed by pickling and passivation.

Quality Certifications & Regulatory Compliance:

ISO 9001:2015 Certified

PED 2014/68/EU (CE Marking)

EN 10204 3.2 Certification with third-party validation (TÜV, BV, SGS, LR)

Third-Party Inspection (TPI) approved by SGS, BV, ABS, DNV, TÜV

NORSOK M-650 (mandatory for offshore super duplex applications)

DNV GL approval for super duplex pipes

NACE MR0175 / ISO 15156 for sour service (H₂S)

Womic Steel supplies super duplex welded pipes to over 40 countries across offshore, chemical, desalination, and geothermal industries.

Production Flexibility:

ERW: 6.35–610mm OD × 0.5–12.7mm WT × ≤ 12m

EFW: 219–1219mm OD × 4.0–50mm WT × ≤ 12m (longer upon request)

LSAW: 406–1524mm OD × 6.0–60mm WT × ≤ 18m

Finishing options: Annealed and pickled, bright annealed (for tubing)

ASTM A790 S32750: Material Composition & Performance Characteristics

UNS S32750 is a super duplex stainless steel with high chromium (25%), high molybdenum (4%), and high nitrogen (0.27%) content. It offers significantly higher pitting and crevice corrosion resistance than standard duplex 2205, making it suitable for the most aggressive chloride and sulfide environments, including high-temperature seawater, acidic brines, and high H₂S sour service. The high nitrogen content also promotes austenite formation and improves weldability.

Chemical Composition (Ladle Analysis, % by mass):

Element	UNS S32750 (ASTM A790)	UNS S32760 (for comparison)
C	≤ 0.030	≤ 0.030
Mn	≤ 1.20	≤ 1.00
P	≤ 0.035	≤ 0.030
S	≤ 0.020	≤ 0.010
Si	≤ 0.80	≤ 1.00
Cr	24.0 – 26.0	24.0 – 26.0
Ni	6.0 – 8.0	6.0 – 8.0
Mo	3.0 – 5.0	3.0 – 4.0
N	0.24 – 0.32	0.20 – 0.30
Cu	≤ 0.50	0.50 – 1.00
W	—	0.50 – 1.00
Fe	Balance	Balance

Mechanical Properties (Room Temperature, Solution Annealed):

Property	S32750 (Super Duplex 2507)
Yield Strength (min, 0.2% offset)	550 MPa (79,800 psi)
Tensile Strength (min)	795 MPa (115,300 psi)
Elongation (min, 50mm gauge)	25%
Hardness (max)	90 HRB (or 290 HV)
Impact Toughness (min) @ -46°C	27 J (Charpy V-Notch, typical 80-150J)

Physical Properties:

Density: 7.80 g/cm³

Modulus of Elasticity: 200 GPa (29 × 10⁶ psi)

Thermal Conductivity: 15 W/m·K at 100°C

Coefficient of Thermal Expansion: 13.0 × 10⁻⁶/°C (20-100°C)

Corrosion Resistance:

Pitting Resistance Equivalent Number (PREN) = Cr% + 3.3(Mo%) + 16(N%) ≥ 40 (typically 42-45)

Excellent resistance to pitting and crevice corrosion in chloride environments up to high temperatures (critical pitting temperature > 80°C in seawater)

Outstanding resistance to chloride stress corrosion cracking (SCC)

Excellent resistance to sulfide stress cracking (SSC) for sour service (NACE MR0175)

Good resistance to organic acids, phosphoric acid, and caustic solutions

Superior erosion-corrosion resistance

Microstructure Requirements (per ASTM A790): Ferrite content shall be 40-60% after solution annealing. Womic performs ferrite measurement using image analysis per ASTM E562 on every heat and every weld qualification.

Dimensional Range & Standards Compliance

Item	Specification
Standard	ASTM A790 / ASME SA790 (pipe); ASTM A789 (tubing)
Manufacturing Processes	ERW, EFW, LSAW
Outside Diameter Range	ERW: 6.35 – 610mm; EFW/LSAW: 219 – 1524mm
Wall Thickness Range	ERW: 0.5 – 12.7mm; EFW/LSAW: 4.0 – 50mm
Schedule Range	5S, 10S, 40S, 80S (for NPS 1/8″ – 48″)
Length Range	Standard: 6m; Extended: 12m, 18m, up to 24m
End Finish	Plain End (PE), Beveled End (BE)
Surface Finish	Annealed & Pickled, Bright Annealed
Tolerances	OD: ±0.5% or ±3.2mm; WT: ±12.5% (per ASTM A999); Length: +50mm / -0mm

Available Dimensions & Specifications – ASTM A790 S32750 Welded Super Duplex Pipe (Selected Typical Sizes)

NPS	OD (mm)	Schedule	WT (mm)	Weight (kg/m)	Standard Length	Typical Application
1/2″	21.3	80S	3.73	1.62	6m	Subsea control line
3/4″	26.7	80S	3.91	2.20	6m	Chemical injection
1″	33.4	80S	4.55	3.24	6m	Umbilical tube
1-1/2″	48.3	80S	5.08	5.41	6m	Hydraulic line
2″	60.3	80S	5.54	7.48	6m / 12m	Seawater lift
3″	88.9	40S	5.49	11.3	6m / 12m	Firewater main
4″	114.3	40S	6.02	16.1	6m / 12m	Brine line
6″	168.3	40S	7.11	28.3	6m / 12m	SWRO high pressure
8″	219.1	40S	8.18	42.6	12m	Offshore headers
10″	273.0	40S	9.27	60.3	12m	FGD recirc line
12″	323.9	40S	10.31	79.8	12m	Geothermal brine
16″	406.4	40S	12.70	123.4	12m	Large diameter
20″	508.0	40S	15.09	183.5	12m	Main seawater
24″	609.6	40S	17.48	255.5	12m	High volume

Custom dimensions outside these ranges available. Super duplex pipes require longer lead times due to specialized plate/strip sourcing.

Common Super Duplex Stainless Steel Standards & Grades Manufactured by Womic Steel

Standard	Steel Grades	Typical Application	Welding Process
ASTM A790	S32750, S32760, S32550	Offshore, chemical, geothermal	EFW/LSAW
ASTM A789	S32750, S32760	Tubing, heat exchanger	ERW (cold finished)
ASTM A928	S32750, S32760	Electric fusion welded super duplex	EFW
EN 10217-7	1.4410 (2507)	Pressure purposes	SAW/ERW
NORSOK M-630	25Cr (2507)	Offshore Norwegian sector	EFW/LSAW

Usage: High-temperature seawater, SWRO high-pressure, FGD absorbers, geothermal brine, sour service with high H₂S and chlorides, subsea umbilicals.

Manufacturing Process – Welded Super Duplex Stainless Steel Pipe (ERW, EFW, LSAW)

Super duplex welding requires extreme control of heat input, interpass temperature, and post-weld heat treatment. The high alloy content (25% Cr, 4% Mo, 0.27% N) makes the material prone to intermetallic phase precipitation (sigma, chi) if cooling is too slow or if heat input is excessive.

ERW (Electric Resistance Welding) Process – Small to Medium Diameter (6.35–610mm OD):

Raw Material (Strip/Coil) Inspection: Super duplex strip verified for S32750 composition (Cr 24-26%, Mo 3-5%, N 0.24-0.32%). Each coil has unique heat number.

Uncoiling & Leveling

Strip Edge Trimming

Forming: Continuous roll forming.

High-Frequency Welding: Very low heat input (≤ 1.2 kJ/mm). Welding speed optimized to minimize heat-affected zone width.

Seam Annealing: Immediate induction annealing after weld, followed by water quench.

Sizing & Straightening

Cutting to Length

NDT: Eddy current test (100%) + optional UT.

Solution Annealing (Full Pipe): 1070-1120°C, water quench (mandatory for all super duplex).

Hydrostatic Test

Pickling & Passivation

Ferrite Measurement: 40-60% ferrite.

Final Inspection & Marking

EFW (Electric Fusion Welding) Process – Large Diameter (219–1219mm OD, 4.0–50mm WT):

Plate Preparation: Super duplex plate, edges beveled (X bevel).

Roll Forming

Tack Welding

TIG (GTAW) Root Pass: Matching super duplex filler (ER2594), nitrogen backing gas (minimum 5% N₂ in Ar) to prevent nitrogen loss.

SAW Fill & Cap Passes: Heat input ≤ 1.5 kJ/mm, interpass temperature ≤ 100°C. Special basic flux for super duplex.

Inner Weld (for large diameters)

100% RT + UT (per ASTM A928)

Solution Annealing: Full pipe heat treatment in car-bottom furnace (1070-1120°C), water quench.

Pickling & Passivation

Hydrostatic Test

Ferrite Measurement & PMI

Dimensional Inspection & Marking

LSAW Process for Super Duplex – Very Large Diameter (406–1524mm OD, 6.0–60mm WT):

UOE or JCOE forming from super duplex plate

Double-sided SAW welding with heat input ≤ 1.5 kJ/mm

Full solution annealing after welding

Ferrite measurement on every pipe

Critical Control Points for Super Duplex Welding:

Heat input: ≤ 1.5 kJ/mm (target ≤ 1.2 kJ/mm for optimal properties)

Interpass temperature: ≤ 100°C (strictly enforced)

Backing gas: Minimum 5% N₂ in Ar (or 10-20% N₂ for best results)

Cooling rate after welding: Rapid (assisted with cooling air if needed)

Solution annealing: 1070-1120°C, water quench – mandatory, cannot be omitted.

Ferrite content: 40-60% (target 45-55%)

Quality Control & Testing Procedures for ASTM A790 S32750 Welded Super Duplex Pipe

Stage	Inspection Method	Purpose
Raw Material	Chemical Analysis (OES)	Verify S32750 (Cr 24-26%, Mo 3-5%, N 0.24-0.32%)
Raw Material	Tensile Testing	Yield ≥ 550 MPa, Tensile ≥ 795 MPa
Raw Material	Ferrite Measurement	Starting plate 40-60%
Raw Material	Charpy @ -46°C	≥ 27 J (typical 80-150 J)
Raw Material	Intergranular Corrosion Test (ASTM A262)	No sensitization
In-Process	Heat Input Monitoring	≤ 1.5 kJ/mm (EFW/LSAW)
In-Process	Interpass Temperature	≤ 100°C
In-Process	Cooling Rate	Rapid cooling between passes
Weld (ERW)	Eddy Current (100%)	Weld integrity
Weld (EFW/LSAW)	100% PAUT (Phased Array UT)	Detect intermetallic phases and weld defects
Weld (EFW/LSAW)	RT (100% for Class 1)	Weld quality
Weld	Dye Penetrant (PT)	Surface cracks
After Solution Annealing	Ferrite Measurement (ASTM E562)	40-60% (target 45-55%)
After Solution Annealing	Hardness Test	≤ 90 HRB (or 290 HV)
After Solution Annealing	Microstructure (SEM/EDS)	No sigma, chi, or R-phase
Finished Pipe	Hydrostatic Test	Pressure integrity
Finished Pipe	Charpy @ -46°C (weld + HAZ)	≥ 27 J (typical 60-120 J)
Finished Pipe	Pitting Corrosion Test (ASTM G48 Method A)	No pitting at 40°C, 24h (more severe than for 2205)
Finished Pipe	CPT (Critical Pitting Temperature)	≥ 80°C in seawater (by agreement)
Finished Pipe	PMI (XRF)	Confirm grade (Cr, Mo, N)
Finished Pipe	Visual & Marking	Traceability

Optional Tests for Critical Offshore Service (NORSOK M-650):

Ferrite measurement on weld (5 positions across weld)

Microstructure for intermetallic phases (sigma, chi, R-phase) – 500x and 1000x

Hardness traverse across weld (max 320 HV)

Corrosion testing in simulated seawater with chlorination

Hydrogen induced cracking (HIC) test (for sour service)

Primary Applications – ASTM A790 S32750 Welded Super Duplex Stainless Steel Pipe

Offshore oil and gas platforms (high-temperature seawater): Seawater lift pumps (pressures 10-20 bar, temperatures 30-50°C), firewater systems, cooling water mains. S32750 resists pitting at higher temperatures where 2205 may fail.

Seawater reverse osmosis (SWRO) high-pressure piping: Feed and reject lines operating at 70-100 bar (1,000-1,500 psi) with high chloride brines (up to 70,000 ppm TDS). S32750's high strength allows thinner walls.

Flue gas desulfurization (FGD) systems: Absorber recirculation lines, spray headers, and oxidation air spargers in coal-fired power plants. Resists highly chloridic acidic environment (pH 1-3, Cl⁻ up to 100,000 ppm).

Geothermal energy production: Brine extraction and reinjection lines (high temperature up to 150°C, high chloride, high CO₂, trace H₂S). S32750 resists pitting and SCC.

Marine exhaust scrubbers (SOx removal): Closed-loop scrubbers with seawater wash. S32750 resists sulfuric acid condensation and chlorides.

Chemical processing: Production of phosphoric acid (wet process), titanium dioxide (chloride route), and organic chlorides. S32750 resists reducing-acid attack.

Subsea umbilicals and control lines: Small diameter tubing (1/2″ to 2″) for hydraulic and chemical injection in deepwater oil and gas fields.

Sour service with high H₂S and chlorides: NACE MR0175 qualified for H₂S partial pressures up to 1 bar in high chloride produced water.

Packaging & Shipping – ASTM A790 S32750 Welded Super Duplex Pipe

Packaging:

Anti-corrosion protection: VCI paper or plastic wrap (no oil for sensitive systems). For offshore, heat-sealed plastic bags.

End caps: Stainless steel or heavy-duty plastic caps (color-coded for super duplex – typically blue or yellow).

Bundling (Small diameters): Bundles with steel straps and interleaving paper. Each pipe individually separated.

Individual packaging (Large diameters): Plastic film wrap with foam rings between pipes.

Wooden crates for critical offshore and NORSOK M-650 projects.

Shipping:

Containers for ≤ 610mm, break-bulk for larger diameters.

Documentation: MTC 3.1/3.2 (EN 10204), hydrotest report, PAUT/RT reports, ferrite measurement report, PMI report, Charpy reports (base + weld), G48 pitting report, microstructure report (if required), dimensional report, packing list, COO. NORSOK M-650 dossier upon request.

Womic Steel Advantages & FAQ – ASTM A790 S32750 Super Duplex Welded Pipe

Why Partner with Womic Steel for S32750 Super Duplex?

Complete Size Range: ERW 1/4″ – 24″, EFW/LSAW 8″ – 60″.

Full solution annealing after welding (1070-1120°C, water quench).

In-house ferrite measurement and microstructure examination (SEM/EDS).

NORSOK M-650 qualified for offshore Norwegian sector.

DNV GL approval for super duplex pipes.

Critical pitting temperature (CPT) testing available (ASTM G48 Method D).

Sour service certification (NACE MR0175/ISO 15156).

Lead times: 40-50 days for ERW, 50-70 days for EFW/LSAW.

Frequently Asked Questions (FAQ) – ASTM A790 S32750 Super Duplex Welded Pipe

Q: What is the difference between S32750 and S32760?
A: Both are super duplex grades with similar properties. S32760 typically contains small additions of copper (0.5-1.0%) and tungsten (0.5-1.0%), which can slightly improve corrosion resistance in certain reducing acids. S32750 relies on higher nitrogen (0.24-0.32% vs 0.20-0.30%) and no tungsten. Both have PREN ≥ 40. S32750 is more common in the Americas and Asia; S32760 is more common in Europe. Womic can supply both; please specify your requirement.

Q: What is the maximum service temperature for S32750?
A: S32750 is suitable for continuous service in seawater up to 80°C (critical pitting temperature > 80°C). For chloride-free environments, it can be used up to 280°C. Above 280°C, embrittlement due to sigma phase formation occurs. For high-temperature (> 300°C) applications, nickel-based alloys (Alloy 625, C-276) are recommended.

Q: Why is solution annealing mandatory for super duplex welded pipe?
A: Super duplex has high chromium and molybdenum, making it very prone to sigma phase precipitation in the HAZ if cooling is too slow. Solution annealing at 1070-1120°C dissolves any intermetallic phases and restores the ferrite/austenite balance. Without proper solution annealing, the pipe will have poor corrosion resistance and low toughness. Womic performs full solution annealing on all super duplex welded pipes.

Q: Can S32750 be used for sour service (H₂S)?
A: Yes, S32750 is qualified for sour service per NACE MR0175/ISO 15156 for H₂S partial pressures up to 1.0 bar (15 psi) in specific hardness ranges (≤ 28 HRC). Womic supplies S32750 with hardness ≤ 27 HRC and full HIC/SSC testing upon request. For very high H₂S (> 1 bar), nickel-based alloys may be required.

Q: What is the pitting resistance equivalent (PREN) of S32750?
A: PREN = Cr% + 3.3(Mo%) + 16(N%). For S32750 with nominal composition 25% Cr, 4% Mo, 0.27% N, PREN ≈ 25 + 13.2 + 4.3 = 42.5. Minimum PREN per ASTM is 40. This is significantly higher than 2205 (PREN 35-38) and much higher than 316L (PREN 24-26). S32750 can resist pitting in seawater up to 80°C.

Q: Do you provide NORSOK M-650 certification?
A: Yes. Womic Steel is qualified to NORSOK M-650 for super duplex stainless steel welded pipes. We provide full documentation including ferrite measurement (weld, HAZ, base metal), hardness traverses, microstructure examination (500x and 1000x for intermetallic phases), and corrosion testing. This is mandatory for offshore projects on the Norwegian continental shelf.

Q: What is the typical lead time for S32750 super duplex welded pipe?
A: 40-50 days for ERW (small to medium diameters), 50-70 days for EFW/LSAW (large diameters). NORSOK M-650 documentation adds 15-20 days. Third-party inspection adds 7-14 days. Lead times are longer than for standard duplex due to specialized plate/strip sourcing from certified mills.

Q: What welding filler metal is recommended for S32750?
A: AWS A5.9 ER2594 (or ERNiCrMo-13) filler metal is required for matching super duplex properties. Womic uses ER2594 for TIG root passes and SAW fill passes. We also provide welding procedure qualification (WPQ) samples and recommended WPS for field welding.

Project Reference – Arabian Gulf Seawater Lift Pumps & Firewater System (UAE)

Country: United Arab Emirates (Abu Dhabi, offshore oil field)
Standard & Grade: ASTM A790 S32750 (Super Duplex 2507) – NORSOK M-650 qualified
Dimensions & Quantity:

OD 219.1mm (8″) × Schedule 40S (8.18mm WT) – 1,200 meters (approx. 40 tons) – EFW process

OD 323.9mm (12″) × Schedule 40S (10.31mm WT) – 800 meters (approx. 58 tons) – EFW process

OD 88.9mm (3″) × Schedule 80S (7.62mm WT) – 2,500 meters (approx. 35 tons) – ERW process

OD 60.3mm (2″) × Schedule 80S (5.54mm WT) – 3,000 meters (approx. 23 tons) – ERW process
Total: 7,500 meters (7.5 km), approx. 156 tons

Specifications: ASTM A790 S32750 solution annealed and pickled, beveled ends. Hydrostatic testing. 100% PAUT for EFW pipes, eddy current + UT for ERW. PMI on every pipe. Mandatory ferrite measurement (40-60%, achieved 45-55%). Charpy impact at -46°C (spec 27J, achieved 90-160J). Pitting corrosion test per ASTM G48 Method A at 40°C (more severe than standard 22°C) – no pitting. Critical pitting temperature (CPT) per ASTM G48 Method D – achieved CPT ≥ 85°C. NORSOK M-650 documentation including microstructure examination (no sigma/chi phases) and hardness traverses. Third-party inspection by DNV UAE. NACE MR0175 compliance for sour service (trace H₂S in produced water).

Application: Seawater lift pump discharge piping and firewater ring main for an offshore oil production platform in the Arabian Gulf. Seawater temperature: 35-40°C in summer (up to 42°C), salinity 45,000-50,000 ppm, with chlorination (0.5 ppm residual Cl₂). The system supplies cooling water to process equipment and firewater for platform safety. Previous 2205 duplex piping experienced pitting after 5 years due to elevated seawater temperature and chlorination. S32750 was selected for its higher critical pitting temperature (> 80°C vs 2205's 50-60°C) and higher strength.

Technical Challenges & Solutions:

High temperature seawater (up to 42°C) with chlorination – Arabian Gulf seawater in summer reaches 40-42°C, and chlorination for biofouling control increases the oxidizing potential. Standard duplex 2205 has CPT of 50-60°C, which is borderline. S32750 with CPT ≥ 85°C provides margin. Womic performed G48 Method D CPT testing: critical temperature measured 85-92°C. Also performed pitting test at 40°C for 72 hours – no pitting. Client accepted.

Strict ferrite control and microstructure – NORSOK M-650 requires ferrite between 40-60% and no intermetallic phases. Womic performed ferrite measurement on 20% of pipes (weld + HAZ + base metal). Results: weld 48-54%, HAZ 45-52%, base metal 47-56%. Microstructure examination (500x and 1000x) showed no sigma, chi, or R-phase. Hardness max 285 HV10 (well below 320 HV limit).

Welding procedure qualification for field repairs – Platform installation required field welding of super duplex. Womic provided WPS using ER2594 filler, with heat input ≤ 1.5 kJ/mm, interpass ≤ 100°C, and nitrogen backing gas. We supplied 30 weld coupons for qualification. All passed radiographic, PT, Charpy at -46°C (weld 80-120J, HAZ 90-130J), and ferrite measurement.

Lightweight design using Schedule 40S – S32750's high strength (550 MPa yield) allowed use of Schedule 40S instead of heavier Schedule 80S used for 2205. This reduced pipe weight by 35%, saving 25 tons of structural steel on the platform. Womic provided dimensional verification reports.

Logistics to offshore platform – Pipes shipped from Shanghai to Abu Dhabi, then to offshore platform via supply vessel. DNV witnessed loading and stowage. All 156 tons delivered in two shipments over 6 weeks. NORSOK M-650 documentation package (550 pages) delivered electronically within 10 days of shipment.

Result: Seawater lift and firewater system commissioned in Q4 2023. After 18 months of operation with seawater temperatures up to 42°C, inspection using remotely operated vehicle (ROV) showed no pitting, no crevice corrosion, and no cracking. The operator has upgraded their material specification for all Arabian Gulf seawater systems to S32750 for new platforms. Womic Steel has been added to the operator's approved supplier list for super duplex piping under NORSOK M-650.

Contact:
Website: www.womicsteel.com
E-mail: sales@womicsteel.com

Tel / WhatsApp / WeChat:
Victor: +86 15575100681
Jack: +86 18390957568

Womic Steel – Your reliable partner for ASTM A790 S32750 super duplex stainless steel welded pipes for high-temperature seawater, offshore platforms, desalination, FGD, and geothermal applications worldwide.