Duplex S31803 Buttweld Fitting Manufacturer
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For high pressure pipelines and corrosive industrial settings, Midland Alloys Inc. is a reliable manufacturer and supplier of Duplex Steel UNS S31803 Buttweld Fittings. High yield strength, superior durability in aggressive media and outstanding resistance to chloride stress corrosion are all feature of these fittings. We provide a large range of products that are made in accordance with ASTM A815, ASME B16.9 and ANSI B16.28 standards such as elbows, tees, reducers, stub ends, crosses and end caps. Our Duplex S31803 buttweld fittings come in concentric and eccentric reducers, as well as seamless and welded long and short radius elbows. We provide customised sizes, technical documentation such as mill test certificates (MTC), and maintain a ready stock to ensure short lead times. As an ISO 9001:2015 certified company, we focus on quality, competitive pricing, and timely dispatch for both domestic and international markets.
We are a top manufacturer and supplier of Duplex S31803 Buttweld Fitting offering precisely engineered solutions that satisfy all industrial requirements. We provide client with dependable service and stringent quality control.
What Is S31803 Buttweld Fittings?
S31803 Buttweld pipe fittings are welded parts manufactured for use in duplex stainless steel piping systems. These fittings are made of ferritic austenitic stainless steel (UNS S31803) which has a stable dual phase microstructure due to the controlled amounts of chromium, nickel and molybdenum. Reliable fabrication is supported by this structure’s consistency throughout the forming and welding process.
Duplex S31803 buttweld pipe fittings are crafted to meet the standards set by ASTM A815, ASME SA815 and ASME B16.9, ensuring they have a consistent wall thickness and precise dimensional control. To keep everything stable and allow for smooth alignment in duplex piping systems these fittings undergo proper heat treatment. They meet rigorous engineering standards across various industrial specifications and are available in a wide range of sizes and types.
Benefits of Duplex Steel S31803 Buttweld Fittings
ASME B16.9 Duplex S31803 fittings are frequently utilized in pipe systems where dependability, strength, and resistance to corrosion are crucial. Below are some key benefits that make Duplex S31803 fittings a preferred choice in various industries:
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and chloride stress corrosion cracking.
- High Strength and Durability: Higher mechanical strength than standard austenitic stainless steels, ensuring long-term performance under pressure.
- Weldability and Fabricability: Good weldability and ease of fabrication allow for efficient installation and customization.
- Cost-Effectiveness: Combines strength and corrosion resistance, reducing material thickness and overall project cost.
Specification of S31803 Duplex Butt Weld Pipe Fittings
Duplex S31803 Buttweld Fittings conform to international standards for dimensions, wall thickness, and tolerances. These fittings support seamless integration in duplex stainless steel piping systems used in high-pressure and corrosive conditions.
Below are the key specifications of Duplex Steel UNS S31803 Buttweld Pipe Fittings:
Seamless Butt Weld Fittings: 1/2" - 10" Welded Butt Weld Fittings: 1/2" - 48"
ASTM A815 / ASME SA815
Type of Duplex S31803 Buttweld Fittings
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Elbow (90°, 45°, Long Radius, Short Radius)Modifies the pipeline's flow direction at predetermined angles with regulated radii.
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Tee (Equal Tee, Reducing Tee)Adjusts the size of the main and branch lines to split or combine flow at 90° intersections.
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A reducer (eccentric or concentric)joins pipes with varying diameters while preserving flow offset or alignment.
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stub endIn non-permanent piping configurations, the stub end (long or short) connects to lap joint flanges for disassembly.
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Return Bends (180° bend)Redirects flow by 180 degrees, allowing the pipeline to reverse direction.
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Cross (Equal Cross, Reducing Cross)Provides multidirectional flow by joining four pipes at right angles.
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pipe capTo stop flow or pressure, an end cap also known as a pipe cap, seals the pipe's open end.
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Bend (3D, 5D, Custom Radius)This tool uses predefined or custom radii to gradually change the direction of pipelines.
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nipplesShort pipe segments called "nipples" (also known as "barrel" or "swage") are used to join two fittings or pipes.
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Collar / CouplingLinks two pipe sections in a straight run with a secure and leak-free joint.
Technical Details & Delivery Condition
Ferritic-austenitic stainless steel Duplex S31803 has precisely regulated components that preserve its corrosion resistance and dual-phase structure. The typical chemical composition is listed in the table below:
| Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | Fe |
| S31803 | 0.030 max | 2.00 max | 1.00 max | 0.030 max | 0.020 max | 22.0 – 23.0 | 3.0 – 3.5 | 4.50 – 6.50 | 0.14 – 0.20 | 63.72 min |
| Grade | Density | Melting Point | Tensile Strength | Yield Strength (0.2%Offset) | Elongation |
| S31803 | 7.8 g/cm3 | 1350 °C (2460 °F) | Psi – 116000 , MPa – 800 | Psi – 80000 , MPa – 550 | 15 % |
The following table shows equivalent grades across different international standards and designations.
Below is a sample SS 304/304L pipe weight chart:
| STANDARD | WERKSTOFF NR. | UNS |
| Duplex S31803 | 1.4462 | S31803 / S32205 |
| Products | Size | |
| ASTM A815 Duplex Steel Elbow – Long Radius | ASTM A815 Duplex Steel Stub Ends | Sizes 1/2″ – 48″ |
| ASTM A815 Duplex Steel Elbow – Short Radius | ASTM A815 Duplex Steel Cross | |
| ASTM A815 Duplex Steel Reducing Elbow | ASTM A815 Duplex Steel Reducing Cross | |
| ASTM A815 Duplex Steel 45° Elbow | ASTM A815 Duplex Steel Tees | |
| ASTM A815 Duplex Steel Fabricated Tee | ASTM A815 Duplex Steel End Cap | |
| ASTM A815 Duplex Steel Reducer | ASTM A815 Duplex Steel Coupling | |
| ASTM A815 Duplex Steel Concentric Reducer | ASTM A815 Duplex Steel Pipe Nipple | |
| ASTM A815 Duplex Steel Eccentric Reducer | ASTM A815 Duplex Steel 5D Elbow | |
| ASTM A815 Duplex Steel 3D Elbow | ASTM A815 Duplex Steel Welded Pipe Fittings | |
Duplex & Super Duplex Steel Buttweld Fittings Grades We Offer
Duplex Steel S31803 Buttweld Fitting Schedule
| NB | OD | SCH XXS | SCH 80S | SCH 5S | SCH 160S | SCH 10S | SCH 40S | |||||||
| mm | in. | mm | WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) | Weight (kg/m) | WT (mm) | Weight (kg/m) | WT (mm) | WT (mm) | Weight (kg/m) | WT (mm) | Weight (kg/m) |
| 10 | 3/8 | 17.1 | – | – | 3.20 | 1.10 | 0.490 | 1.24 | – | – | 1.65 | 0.63 | 2.31 | 0.845 |
| 25 | 1 | 33.4 | 9.09 | 5.45 | 4.55 | 3.24 | 1.30 | 1.65 | 4.24 | 6.35 | 2.77 | 2.09 | 3.38 | 2.50 |
| 150 | 6 | 168.3 | 21.95 | 79.22 | 10.97 | 42.7 | 11.32 | 2.77 | 67.56 | 18.2 | 3.40 | 13.84 | 7.11 | 28.3 |
| 15 | 1/2 | 21.3 | 7.47 | 2.55 | 3.75 | 1.62 | 0.800 | 1.65 | 1.94 | 4.75 | 2.11 | 1.00 | 2.77 | 1.27 |
| 40 | 1 1/2 | 48.3 | 10.16 | 9.54 | 5.08 | 5.41 | 1.91 | 1.65 | 7.25 | 7.14 | 2.77 | 3.11 | 3.68 | 4.05 |
| 32 | 1 1/4 | 42.2 | 9.70 | 7.77 | 4.85 | 4.47 | 1.65 | 1.65 | 5.61 | 6.35 | 2.77 | 2.70 | 3.56 | 3.38 |
| 50 | 2 | 60.3 | 11.07 | 13.44 | 5.54 | 7.48 | 2.40 | 1.65 | 11.1 | 8.74 | 2.77 | 3.93 | 3.91 | 5.44 |
| 600 | 24 | 609.6 | – | – | 30.96 | 442.08 | 82.47 | 5.54 | 808.22 | 59.54 | 6.35 | 94.45 | 17.48 | 255.41 |
| 65 | 2 1/2 | 73.0 | 14.2 | 20.39 | 7.01 | 11.4 | 3.69 | 2.11 | 14.9 | 9.53 | 3.05 | 5.26 | 5.16 | 8.63 |
| 80 | 3 | 88.9 | 15.24 | 27.65 | 7.62 | 15.2 | 4.51 | 2.11 | 21.3 | 11.1 | 3.05 | 6.45 | 5.49 | 11.30 |
| 300 | 12 | 323.9 | 25.40 | 186.97 | 12.7 | 132.0 | 31.25 | 3.96 | 238.76 | 33.32 | 4.57 | 36.00 | 9.52 | 73.88 |
| 3 | 1/8 | 10.3 | – | – | 2.41 | 0.47 | 0.276 | 1.24 | – | – | 1.24 | 0.28 | 1.73 | 0.37 |
| 100 | 4 | 114.3 | 17.12 | 41.03 | 8.56 | 22.3 | 5.84 | 2.11 | 33.54 | 13.49 | 3.05 | 8.36 | 6.02 | 16.07 |
| 125 | 5 | 141.3 | 19.05 | 57.43 | 9.53 | 31.97 | 9.47 | 2.77 | 49.11 | 15.88 | 3.40 | 11.57 | 6.55 | 21.8 |
| 250 | 10 | 273.1 | 25.40 | 155.15 | 12.7 | 96.0 | 22.63 | 3.40 | 172.4 | 28.6 | 4.19 | 27.78 | 9.27 | 60.5 |
| 200 | 8 | 219.1 | 22.23 | 107.8 | 12.7 | 64.6 | 14.79 | 2.77 | 111.2 | 23.0 | 3.76 | 19.96 | 8.18 | 42.6 |
| 350 | 14 | 355.6 | – | – | 19.05 | 158.08 | 34.36 | 3.96 | 281.70 | 35.71 | 4.78 | 41.3 | 11.13 | 94.59 |
| 6 | 1/4 | 13.7 | – | – | 3.02 | 0.80 | 0.390 | 1.24 | – | – | 1.65 | 0.49 | 2.24 | 0.631 |
| 400 | 16 | 406.4 | – | – | 21.41 | 203.33 | 41.56 | 4.19 | 365.11 | 40.46 | 4.78 | 47.29 | 12.7 | 123.30 |
| 20 | 3/4 | 26.7 | 7.82 | 3.63 | 3.91 | 2.20 | 1.03 | 1.65 | 2.89 | 5.54 | 2.11 | 1.28 | 2.87 | 1.68 |
| 500 | 20 | 508.0 | – | – | 26.19 | 311.2 | 59.25 | 4.78 | 564.68 | 49.99 | 5.54 | 68.71 | 15.09 | 183.42 |
| 450 | 18 | 457.2 | – | – | 23.8 | 254.36 | 46.80 | 4.19 | 466.40 | 45.71 | 4.78 | 53.42 | 14.27 | 155.80 |
Duplex Steel S31803 Buttweld Fitting Weight Chart
| Pipe Elbow Nominal Size | Pipe Elbow Outside Diameter Y | Wall Thickness T (Pipe Elbow Schedule) | 45 Deg. Elbow LR Centre to Face B | 45 Deg. Elbow LR Weight | 90 Deg. Elbow LR Centre to Face A | 90 Deg. Elbow LR Weight | 90 Deg. Elbow SR Centre to Face A | 90 Deg. Elbow SR Weight | ||
| mm | in | mm | mm | Schedule | mm | kg | mm | kg | mm | kg |
| 15 | 1/2” | 21.3 | 2.78 | STD | 15.9 | 0.04 | 38.1 | 0.08 | – | – |
| 3.73 | X.S | 15.9 | 0.05 | 38.1 | 0.10 | – | – | |||
| 20 | 3/4” | 26.7 | 2.87 | STD | 11.1 | 0.04 | 28.6 | 0.08 | – | – |
| 3.91 | X.S | 11.1 | 0.05 | 28.6 | 0.11 | – | – | |||
| 25 | 1” | 33.4 | 3.38 | STD | 22.2 | 0.09 | 38.1 | 0.15 | 25.4 | 0.11 |
| 4.55 | X.S | 22.2 | 0.11 | 38.1 | 0.19 | 25.4 | 0.14 | |||
| 32 | 11/4” | 42.2 | 3.56 | STD | 25.4 | 0.14 | 47.6 | 0.28 | 31.75 | 0.18 |
| 4.85 | X.S | 25.4 | 0.2 | 47.6 | 0.39 | 31.75 | 0.24 | |||
| 40 | 11/2” | 48.3 | 3.68 | STD | 28.6 | 0.2 | 57.1 | 0.4 | 38.1 | 0.26 |
| 5.08 | X.S | 28.6 | 0.25 | 57.1 | 0.5 | 38.1 | 0.35 | |||
| 50 | 2” | 60.3 | 3.91 | STD | 34.9 | 0.36 | 76.2 | 0.72 | 50.8 | 0.5 |
| 5.54 | X.S | 34.9 | 0.5 | 76.2 | 1.0 | 50.8 | 0.68 | |||
| 65 | 21/2” | 73.0 | 5.16 | STD | 44.4 | 0.73 | 95.2 | 1.46 | 63.5 | 0.95 |
| 7.01 | X.S | 44.4 | 0.91 | 95.2 | 1.82 | 63.5 | 1.27 | |||
| 80 | 3” | 88.9 | 5.49 | STD | 50.8 | 1.1 | 114.3 | 2.18 | 76.2 | 1.45 |
| 7.62 | X.S | 50.8 | 1.45 | 114.3 | 2.86 | 76.2 | 1.95 | |||
| 100 | 4” | 114.3 | 6.02 | STD | 63.5 | 2.1 | 152.4 | 4.2 | 101.6 | 2.8 |
| 8.56 | X.S | 63.5 | 2.9 | 152.4 | 5.7 | 101.6 | 3.9 | |||
| 125 | 5” | 141.3 | 6.65 | STD | 79.4 | 3.4 | 190.0 | 6.8 | 127.0 | 4.8 |
| 9.5 | X.S | 79.4 | 5.0 | 190.0 | 10.0 | 127.0 | 6.5 | |||
| 150 | 6” | 168.3 | 7.11 | STD | 95.2 | 5.1 | 229.0 | 10.1 | 152.4 | 6.8 |
| 10.97 | X.S | 95.2 | 7.7 | 229.0 | 15.3 | 152.4 | 10.2 | |||
| 200 | 8” | 219.1 | 8.18 | STD | 127.0 | 10.2 | 305.0 | 20.4 | 203.0 | 13.6 |
| 12.7 | X.S | 127.0 | 15.5 | 305.0 | 30.9 | 203.0 | 20.9 | |||
| 250 | 10” | 273.9 | 9.27 | STD | 159.0 | 18.1 | 381.0 | 36.1 | 254.0 | 24.1 |
| 12.7 | X.S | 159.0 | 24.4 | 381.0 | 48.8 | 254.0 | 32.5 | |||
| 300 | 12” | 323.9 | 9.52 | STD | 190.0 | 26.6 | 457.0 | 53.1 | 305.0 | 35.4 |
| 12.7 | X.S | 190.0 | 35.0 | 457.0 | 70.0 | 305.0 | 46.7 | |||
| 350 | 14” | 355.6 | 9.52 | STD | 222.0 | 34.1 | 533.0 | 68.1 | 356.0 | 45.4 |
| 12.7 | X.S | 222.0 | 45.0 | 533.0 | 90.0 | 356.0 | 60.0 | |||
| 400 | 16” | 406.4 | 9.52 | STD | 254.0 | 45.0 | 610.0 | 89.3 | 406.0 | 59.5 |
| 12.7 | X.S | 254.0 | 59.0 | 610.0 | 118.0 | 406.0 | 78.7 | |||
| 450 | 18” | 457.0 | 9.52 | STD | 286.0 | 56.5 | 686.0 | 113.0 | 457.0 | 75.6 |
| 12.7 | X.S | 286.0 | 75.0 | 686.0 | 150.0 | 457.0 | 100.0 | |||
| 500 | 20” | 508.0 | 9.52 | STD | 318.0 | 85.0 | 762.0 | 140.0 | 508.0 | 93.5 |
| 12.7 | X.S | 318.0 | 112.5 | 762.0 | 186.0 | 508.0 | 124.0 | |||
| 600 | 24” | 610.00 | 9.52 | STD | 381.0 | 101.5 | 914.0 | 203.0 | 610.0 | 135.0 |
| 12.7 | X.S | 381.0 | 134.5 | 914.0 | 269.0 | 610.0 | 179.0 | |||
Manufacturing Process of S31803 Buttweld Fitting
Choosing certified raw materials that satisfy ASTM A815 and ASME SA815 requirements is the first step in the production of Duplex S31803 Buttweld Fittings. Depending on the type of fitting, hot or cold forming is accomplished by pressing, hammering or extrusion after duplex stainless steel billet or pipe have been cut to the necessary length. Formed components undergo solution annealing heat treatment to stabilise the duplex structure and eliminate residual stresses.
Post heat treatment, the fittings are machined to precise dimensions and tolerances using CNC or conventional methods. The surface undergoes pickling, passivation, or shot blasting to remove scale and achieve a uniform finish. Non destructive testing (NDT) like dye penetrant, ultrasonic or radiographic inspection is performed on each fitting. Dimensional inspection, mechanical testing and the issuance of Mill Test Certificates (MTCs) in compliance with EN 10204 3.1 are examples of final quality checks. Consistency, traceability and adherence to global quality standards like ISO 9001:2015 are guaranteed by the procedure
Pipe
Cutting
Forming
Sizing
Heat Treatment
Pickling
Beveling
Polishing
Sand Blasting
Elbow
Inspection
Analytic
Marking
Packing & Shipping
Industrial Applications for S31803 Duplex Buttweld Fittings
- Oil & Gas: Installed in pipeline networks that are subjected to high pressure and saline environments, both onshore and offshore.
- Chemical Processing: Utilized in transfer lines and reaction vessels that handle corrosive fluids.
- Desalination Plants: Used in brine discharge systems and high salinity feedwater.
- Pulp & Paper Industry: Incorporated into bleach plants and digesters that process chemicals containing chloride.
- Power Plants: Installed in cooling water lines, condensers, and heat exchangers.
- Marine / Shipbuilding: Utilized in seawater cooling applications, pump lines, and ballast systems.
Our headquartered in India, is a recognised exporter of Duplex S31803 Buttweld Fittings to a wide network of global markets. We are a reliable partner in many industrial sectors around the world because our fittings continuously satisfy the technical requirements of global projects.
We continue to export frequently to the Gulf nations such as the United Arab Emirates, Saudi Arabia, Oman, Qatar, and Kuwait, where the infrastructure and oil and gas industries require high-strength, corrosion-resistant piping solutions. With robust supply chains in Germany, the United Kingdom, France, and Italy, as well as in Asia-Pacific countries like Singapore, Malaysia, Indonesia, and South Korea, our presence is still growing.
We also serve emerging markets in Africa and Latin America, including South Africa, Nigeria, Egypt, and Brazil, where industrial growth drives demand for duplex-grade materials.We guarantee timely delivery, flawless port handling, export-quality packaging and correct customs documentation. Our dedication to quality, compliance and the dependability of global logistics has allowed us to establish enduring relationships with distributors, OEMs, EPC companies, government organizations and project contractors.
Why Choose Midland Alloys Inc.
Midland Alloys Inc. is an ISO 9001:2015 certified manufacturer, delivering precision-engineered S31803 Duplex Buttweld Fittings with strict quality control. Our dependable worldwide export network guarantees fast delivery to important projects in a variety of industries. To satisfy particular technical needs, our staff provides custom coil forms, lengths and finishes. We provide quick customer support for any project related questions and maintain full material traceability. With extensive knowledge of S31803 Buttweld pipe fittings, we provide technical compliance, documentation, and prompt service for every order.
FAQs – Duplex Steel S31803 Buttweld Fitting
Yes, both seamless and welded Duplex S31803 buttweld fittings are produced. While welded fittings are appropriate for standard applications where large sizes and cost-effectiveness are required, seamless fittings are recommended for high-pressure and critical systems.
Duplex buttweld pipe fittings S31803 operate dependably at temperatures ranging from moderate to high, usually up to 300°C.
These fittings are available in sizes ranging from ½” NB to 24” NB, with larger dimensions on request. Common types include elbows, tees, reducers, stub ends, crosses, end caps, and bends, available in different schedules and configurations like long/short radius and concentric/eccentric profiles.
