Views: 6 Author: Site Editor Publish Time: 2025-06-03 Origin: Site
Duplex Steel S31803 Buttweld Fittings are a type of welded pipe connector made of duplex stainless steel. They have excellent corrosion resistance and mechanical properties and are widely used in harsh environments such as chemical industry, ocean, oil and gas, papermaking, desalination, etc.
UNS S31803 is a duplex steel of American standard. It has excellent corrosion resistance and strength characteristics, better resistance to local corrosion, and is widely used as a material for chemical equipment. Compared with 316L and 317L austenitic stainless steels, ASTM A815 WPS31803 is superior in resistance to pitting corrosion and crevice corrosion. It has high corrosion resistance. Compared with austenite, it has a lower thermal expansion coefficient and higher thermal conductivity.
SHANGHAI ZHUCHENG PIPE FITTINGS MANUFACTURING CO LTDis a professional manufacturer and supplier of duplex steel buttweld fittings. Duplex stainless steel is an indispensable material in many harsh industrial applications today. It combines the advantages of austenitic stainless steel and ferritic stainless steel to provide excellent performance. We focus on producing high-quality duplex stainless steel butt-weld pipe fittings that meet international standards and customer customization requirements. Choosing our duplex stainless steel buttweld pipe fittings means you have chosen high performance, high reliability and longer service life, especially for piping systems that need to operate in harsh environments in your project. Contact us
Specifications | ASTM A815 / ASME SA815 |
Dimensions | ASME/ANSI B16.9, ASME B16.28, MSS-SP-43 |
Grades | Duplex S31803 |
Size | 1/2” NB to 24″NB in |
Type | Seamless / Welded / Fabricated |
Thickness | Sch 5s, Sch 10s, Sch 40s, Sch 80s, Sch 160s, Sch XXS |
ASME B16.9: This is the dominant standard for factory-made wrought buttwelding fittings in sizes NPS 1/2 through NPS 48 (DN 15 through DN 1200). It covers overall dimensions, tolerances (including wall thickness, outside diameter, end preparation), ratings, testing, and markings for various types of fittings.
MSS-SP-43: This standard applies to wrought stainless steel butt-welding fittings for low-pressure, corrosion-resistant applications. It specifies dimensions and tolerances for lighter-weight fittings than those typically covered by ASME B16.9. It's often referenced for corrosion-resistant fittings where the full thickness range of B16.9 isn't necessary.
EN 10253-4: This standard specifically covers butt-welding pipe fittings of wrought austenitic and austenitic-ferritic (duplex) stainless steels with specific inspection requirements. This standard details the material grades, dimensions, tolerances, and comprehensive inspection and testing requirements, making it suitable for pressure purposes.
EN 10253-3: Also covers wrought austenitic and austenitic-ferritic (duplex) stainless steels but is for fittings without specific inspection requirements. While the material compositions are similar to EN 10253-4, the latter has more stringent inspection protocols.
JIS | KS | UNS | ISO | DIN EN/DIN | EN | ||
SUS 329J3L | STS 329J3L | S31803 | X2CrNiMoN 22-5-3 | X2CrNiMoN 22-5-3 | 1.4462 | X2CrNiMoN 22-5-3 | 1.4462 |
S32205 | |||||||
CHEMICAL | LIMITS | C | Mn | P | S | Si | Cr | Ni | Mo | N |
ASTM A815 UNS 31803 | MIN | |||||||||
MAX | 0.03 | 2.0 | 0.030 | 0.020 | 1.0 | 23 | 6.5 | 3.5 | 0.20 |
MATERIAL | T.S (MPA) | Y.S (MPA) | EL % | HARDNESS |
ASTM A815 UNS 31803 | 620 min | 450 min | 20 min | 290 max |
1. Corrosion Resistance
S31803 stainless steel is a duplex stainless steel composed of ferrite and austenite, exhibiting good corrosion resistance. In corrosive media, the ferritic phase provides higher corrosion resistance, while the austenitic phase offers better toughness and workability. Therefore, S31803 stainless steel demonstrates good corrosion resistance in various corrosive media, effectively resisting the attack of corrosive substances such as chloride ions, oxidizing acids, and organic acids.
2. Strength
S31803 stainless steel possesses good strength and toughness, enabling it to withstand high pressure and impact forces. At room temperature, the yield strength of S31803 stainless steel can exceed 200 MPa, and its tensile strength can surpass 500 MPa. This combination of strength and toughness makes S31803 stainless steel an ideal material for manufacturing high-strength, high-toughness equipment.
3. Workability
S31803 stainless steel exhibits good workability, allowing for various processing operations such as cutting, bending, and welding. During processing, the work hardening rate of S31803 stainless steel is relatively slow, which helps ensure good surface quality after fabrication. Furthermore, S31803 stainless steel also has good weldability and plasticity, meeting the demands of various processing techniques.
Nominal Size | Outside Diameter at Bevel | Center to End | Center to End | Center to Center | Back to Face | ||||||
90° Elbows | 45° Elbows | 90° Elbows | 45° Elbows | 180 Returns | |||||||
DN | NPS | OD | A | B | A | B | O | K | |||
3D | 3D | LR | SR | LR | LR | SR | LR | SR | |||
15 | 1/2 | 21.3 | 38 | 16 | 76 | 48 | |||||
20 | 3/4 | 26.7 | 57 | 24 | 38 | 19 | 76 | 51 | |||
25 | 1 | 33.4 | 76 | 31 | 38 | 25 | 22 | 76 | 51 | 56 | 41 |
32 | 1 1/4 | 42.2 | 95 | 39 | 48 | 32 | 25 | 95 | 64 | 70 | 52 |
40 | 1 1/2 | 48.3 | 114 | 47 | 57 | 38 | 29 | 114 | 76 | 83 | 62 |
50 | 2 | 60.3 | 152 | 63 | 76 | 51 | 35 | 152 | 102 | 106 | 81 |
65 | 2 1/2 | 73 | 190 | 79 | 95 | 64 | 44 | 190 | 127 | 132 | 100 |
80 | 3 | 88.9 | 229 | 95 | 114 | 76 | 51 | 229 | 152 | 159 | 121 |
90 | 3 1/2 | 101.6 | 267 | 111 | 133 | 4、89 | 57 | 267 | 178 | 184 | 140 |
100 | 4 | 114.3 | 305 | 127 | 152 | 102 | 64 | 305 | 203 | 210 | 159 |
125 | 5 | 141.3 | 381 | 157 | 190 | 127 | 79 | 381 | 254 | 262 | 197 |
150 | 6 | 168.3 | 457 | 189 | 229 | 152 | 95 | 457 | 305 | 313 | 237 |
200 | 8 | 219.1 | 610 | 252 | 305 | 203 | 127 | 610 | 406 | 414 | 313 |
250 | 10 | 273 | 762 | 316 | 381 | 254 | 159 |
| 508 | 518 | 391 |
300 | 12 | 323.8 | 914 | 378 | 457 | 305 | 190 | 914 | 609 | 619 | 467 |
350 | 14 | 355.6 | 1067 | 441 | 533 | 356 | 222 | 1067 | 711 | 711 | 533 |
400 | 16 | 406.4 | 1219 | 505 | 610 | 406 | 254 | 1219 | 813 | 813 | 610 |
450 | 18 | 457 | 1372 | 568 | 686 | 457 | 286 | 1372 | 914 | 914 | 686 |
500 | 20 | 508 | 1524 | 632 | 762 | 508 | 318 | 1524 | 1016 | 1016 | 762 |
550 | 22 | 559 | 1676 | 694 | 838 | 559 | 343 | 1676 | 1118 | 1118 | 838 |
600 | 24 | 610 | 1829 | 757 | 914 | 610 | 381 | 1829 | 1219 | 1219 | 914 |
650 | 26 | 660 | 1981 | 821 | 991 | 660 | 406 | ||||
700 | 28 | 711 | 2134 | 883 | 1067 | 711 | 438 | ||||
750 | 30 | 762 | 2286 | 964 | 1143 | 762 | 470 | ||||
800 | 32 | 813 | 2438 | 1010 | 1219 | 813 | 502 | ||||
850 | 34 | 864 | 2591 | 1073 | 1295 | 864 | 533 | ||||
900 | 36 | 914 | 2743 | 1135 | 1372 | 914 | 565 | ||||
950 | 38 | 965 | 2896 | 1200 | 1448 | 965 | 600 | ||||
1000 | 40 | 1016 | 3048 | 1264 | 1524 | 1016 | 632 | ||||
1050 | 42 | 1067 | 3200 | 1326 | 1600 | 1067 | 660 | ||||
1100 | 44 | 1118 | 3353 | 1389 | 1676 | 1118 | 695 | ||||
1150 | 46 | 1168 | 3505 | 1453 | 1753 | 1168 | 727 | ||||
1200 | 48 | 1219 | 3658 | 1516 | 1829 | 1219 | 759 | ||||
TOLERANCES FOR BW FITTINGS | |||||||||||||
Nominal Size | All Fittings | 45 。& 90 |
| 180 ° | Caps | Reducers | Lap Joint Stub Ends | ||||||
DN | NPS | OD 3) 4) | ID 3) |
| A B |
| K | U | E, E1 | H F |
| R | t |
15-65 | 1/2 -21/2 | +1.6 | ± 0.8 | ± 2 | ± 3 | ± 6 | ± 6 | ± 1 | ± 3 | ± 2 | 0 | 0 | +1.6 |
80-90 | 3-31/2 | ± 1.6 | ± 1.6 | ± 2 | ± 3 | ± 6 | ± 6 | ± 1 | ± 3 | ± 2 | 0 | 0 | +1.6 |
100 | 4 | ± 1.6 | ± 1.6 | ± 2 | ± 3 | ± 6 | ± 6 | ± 1 | ± 3 | ± 2 | 0 | 0 | +1.6 |
125-200 | 5-8 | +2.4 | ± 1.6 | ± 2 | ± 3 | ± 6 | ± 6 | ± 1 | ± 6 | ± 2 | 0 | 0 | +1.6 |
250-450 | 10-18 | +4.0 | ± 3.2 | ± 2 | ± 3 | ± 10 | ± 6 | ± 2 | ± 6 | ± 2 | 0 | 0 | +3.2 |
500-600 | 20-24 | +6.4 | ± 4.8 | ± 2 | ± 3 | ± 10 | ± 6 | ± 2 | ± 6 | ± 2 | 0 | 0 | +3.2 |
650-750 | 26-30 | +6.4 | ± 4.8 | ± 3 | ± 6 | --- | --- | --- | ± 10 | ± 5 | --- | --- | --- |
800-1200 | 32-48 | +6.4 | ± 4.8 | ± 5 | ± 6 | --- | --- | --- | ± 10 | ± 5 | --- | --- | --- |
1300-1500 | 52-60 | +6.4 | ± 4.8 | ± 5 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
1600-1700 | 64-68 | +6.4 | ± 4.8 | ± 5 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
1800-2000 | 72-80 | +6.4 | ± 4.8 | ± 5 | --- | --- | --- | --- | --- | --- | --- | --- | --- |
ASME B16.9 ASTM A815 WPS 31803 Buttweld Elbow | ASME B16.9 ASTM A815 WPS 31803 Reducer |
ASTM A815 UNS S31803 45 Deg 3D Elbow | ASTM A815 WPS 31803 Straight Cross |
ASTM A815 UNS S31803 90 Deg 3D Elbow | ASTM A815 WPS 31803 Reducing Cross |
A815 Duplex Steel 180 Deg Short Radius Elbow | ASME B16.9 ASTM A815 WPS 31803 End Cap |
A815 Duplex Steel 180 Deg Long Radius Elbow | |
ASTM A815 UNS S31803 Equal Tee | SA 815 UNS S31803 Welded Pipe Fittings |
ASTM A815 WPS 32750 Reducing Tee | ASTM A815 UNS S31803 Seamless Pipe Fitting |
Neutral chloride environments
Refining industry
Petrochemical and chemical industry
Pipelines for the chemical industry
Oil and gas industry
Pulp and paper industry
Energy and environmental protection industry
Light industry and food industry
Equipment for the food and pharmaceutical industry
High-strength structural components
Subsea pipelines
Reverse osmosis desalination equipment
Sulfuric acid plants
Fasteners for marine engineering
-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)
-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )
-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)
-Round bar , Billet (ASTM A276, ASTM A479)
- Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)
-Bolting, Nuts（ASTM A193, A194, A320）
We Export Duplex Steel S31803 Buttweld Fittings to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan, Europe, Africa, Asia, North America, South America, Middle East.etc
1. What is Buttweld fitting?
Buttweld fittings are made with beveled ends at both ends during manufacturing, and are connected to the pipeline by butt welding to form a continuous, non-mutated flow channel. They have good sealing, strength and fluid fluidity, and are particularly suitable for working conditions with high strength and high reliability requirements.
2. Is S31803 duplex or super duplex?
S31803 is a duplex stainless steel, not a super duplex.
UNS S31803 is the Unified Numbering System designation for a standard duplex stainless steel.
Super duplex stainless steels, such as UNS S32750 (2507) and UNS S32760, have higher alloying content (especially chromium, molybdenum, and nitrogen) compared to S31803, which gives them even greater corrosion resistance, particularly against pitting and crevice corrosion, and higher strength.
3. What is the difference between S31803 and SS316?
Although both S31803 and SS316 are stainless steels, they differ significantly in microstructure, strength and corrosion resistance. SS316 is an austenitic stainless steel characterized by good toughness, easy processing, good corrosion resistance, and stable performance over a wide temperature range, but its strength is relatively average. S31803 is a duplex stainless steel. As the name suggests, its microstructure is half austenite and half ferrite. This unique structure gives it a yield strength about twice that of SS316, and it performs better in resistance to chloride ion stress corrosion cracking and pitting, giving it a longer service life and higher reliability in more severe corrosive environments.
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