ARK Stainless Inc. is a trusted manufacturer and exporter of high-quality Stainless Steel Buttweld Fittings, offering a wide range of grades to meet the demanding needs of diverse industrial applications. Engineered with precision, our buttweld fittings ensure robust leak-proof connections, smooth flow transitions, and superior mechanical strength across complex piping systems.
Available in various stainless steel grades such as 304, 304L, 304H, 309, 310, 310S, 316, 316L, 316Ti, 317, 317L, 321, 321H, 347, 347H, and 904L, our fittings are manufactured in compliance with ASME B16.9, MSS SP-43, and ASTM A403 standards. Whether it’s for high-temperature services, corrosive environments, or hygienic processing, our fittings deliver outstanding performance and durability.
We offer a comprehensive range of buttweld fitting types including elbows, tees, reducers, caps, stub ends, and customized components. These fittings are widely used in industries such as oil & gas, petrochemicals, power generation, pharmaceuticals, food processing, water treatment, and marine.
At ARK Stainless Inc., quality is at the core of everything we do. Each fitting undergoes rigorous testing and quality checks to ensure dimensional accuracy, structural integrity, and long-term reliability in critical service conditions.
| C | Mn | Si | P | S | Cr | Mo | Ni | N | |
|---|---|---|---|---|---|---|---|---|---|
| 304 | 0.07max | 2.0max | 0.75max | 0.045max | 0.03max | min: 18.0 max: 20.0 | - | min: 8.0 max: 10.5 | — |
| 304L | 0.03max | 2.0max | 0.75max | 0.045max | 0.03max | min: 18.0 max: 20.0 | - | min: 8.0 max: 12.0 | 0.10 max |
| 304H | min: 18.0 max:20.0 |
min: 8.0 max: 10.5 |
min: 0.04 max:0.10 |
0.75 max |
2.0 max |
0.045 max |
- | 0.03 max |
0.10 max |
| 309 | 0.20 max | 2 max | 1 max | 0.045 max | 0.030 max | 23 max | - | 14 max | – |
| 310 | 0.25 max | 2 max | 1.50 max | 0.045 max | 0.03 max | 24 – 26 | - | 19 – 22 | – |
| 310S | 0.08 max | 2 max | 1.50 max | 0.045 max | 0.03 max | 24 – 26 | - | 19 – 22 | – |
| 316 | 0.08 max |
2.0 max |
0.75 max |
0.045 max |
0.03 max |
min: 16.0 max: 18.0 |
min: 2.0 max: 3.0 |
min: 10.0 max: 14.0 |
0.10 max |
| 316L | 0.03 max |
2.0 max |
0.75 max |
0.045 max |
0.03 max |
min: 16.0 max: 18.0 |
min: 2.0 max: 3.0 |
min: 10.0 max: 14.0 |
0.10 max |
| 316TI | - | - | - | - | - | 16.0 | 2.00 | 10.0 | - |
| 0.08 | 2 | 0.75 | 0.045 | 0.03 | 18.0 | 3.00 | 14.0 | 0.1 | |
| 317 | 0.08 max | 2 max | 1 max | 0.040 max | 0.03 max | 18 – 20 | 3 – 4 | 11 – 14 | - |
| 317L | 0.035 max | 2 max | 1 max | 0.040 max | 0.03 max | 18 – 20 | 3 – 4 | 11 – 15 | - |
| 321 | max:0.08 | max:2.0 | max:0.75 | max:0.045 | max:0.03 | min:17.0 max:19.0 |
– | min: 9.0 max:12.0 |
max:0.10 |
| 321H | min:0.04 max:0.10 |
max:2.0 | max:0.75 | max:0.045 | max:0.03 | min:17.0 max:19.0 |
– | min: 9.0 max:12.0 |
max:0.10 |
| 347 | 0.08 max | 2.0 max | 0.75 max | 0.04 max | 0.03 max | min: 17.0 max: 20.0 |
min:10x C max: 1.0 |
min: 9.0 max: 13.0 |
– |
| 347H | min: 0.04 max: 0.10 |
2.0 max | 0.75 max | 0.03 max | 0.03 max | min: 17.0 max: 20.0 |
min:10x C max: 1.0 |
min: 9.0 max: 13.0 |
– |
| 904L | 0.02 max | 4.0 – 5.0 | – | 0.045 max | 0.035 max | 19.0 – 23.0 | 23.0 – 28.0 | 2.0 max | – |
| Grade | Tensile Strength (ksi / MPa) | Yield Strength 0.2% (ksi / MPa) | Elongation (%) | Hardness (Brinell) MAX | Hardness (Rockwell B) MAX |
|---|---|---|---|---|---|
| 304 | 75 / 515 | 30 / 205 | 40 | 201 | 92 |
| 304L | 70 / 485 | 25 / 170 | 40 | 201 | 92 |
| 304H | 75 / 515 | 30 / 205 | 40 | 201 | 92 |
| 309 | 89.9 / 620 | 45 / 310 | 45 | – | – |
| 310 | 75 / 515 | 30 / 205 | 35 | – | – |
| 310S | 75 / 515 | 30 / 205 | 35 | – | – |
| 316 | 75 / 515 | 30 / 205 | 40 | 217 | 95 |
| 316L | 70 / 485 | 25 / 170 | 40 | 217 | 95 |
| 316Ti | 515 MPa | 205 MPa | 35 | 205 | 75 |
| 317 | 75 / 515 | 30 / 205 | 35 | – | – |
| 317L | 75 / 515 | 30 / 205 | 35 | – | – |
| 321 / 321H | 75 / 515 | 30 / 205 | 40 | 217 | – |
| 347 / 347H | 75 / 515 | 30 / 205 | 40 | 201 | 95 |
| 904L | 490 MPa | 220 MPa | 36 | 150 | 70–90 (typical) |
The properties of SS 304/304L/304H Buttweld Fittings are excellent weldability with and without fillers, stainless steel 304H offers higher strength at elevated temperatures, good machining properties, good resistance to carbide precipitation, good oxidation resistance in intermittent service to 870 degree Celsius and continuous to 920 degrees., excellent resistant to corrosion in all types of environment. The application of this fitting are springs, industrial fabrications, threaded fasteners, heat exchangers, pharmaceuticals and chemical process equipment, architectural railings, equipment and appliances, food processing equipment. The packaging is done in wooden pallets and cases after proper testing only.
| STANDARD | UNS | WNR. | AFNOR | EN | JIS | BS | GOST |
|---|---|---|---|---|---|---|---|
| SS 304 | S30400 | 1.4301 | Z7CN18‐09 | X5CrNi18-10 | SUS 304 | 304S31 | 08Х18Н10 |
| SS 304L | S30403 | 1.4306/1.4307 | Z3CN18‐10 | X2CrNi18-9 / X2CrNi19-11 | SUS 304L | 304S11 | 03Х18Н11 |
| SS 304H | S30409 | 1.4301 | - | - | - | - | - |
SS 309 is the austenitic grade alloy stainless steel which is widely used in industrial applications. However, the alloy is used in the applications which are working with the high-temperature environments. This is the reason that the buttweld fittings are having good corrosion resistance ability.
The SS 310 is another stainless steel version of grade which is used in the development of the buttweld fittings. This is the way that the fittings are working in elevated temperatures. Another way is using the SS 310S, it is the alloying grade which is modified as per the version of the 310-grade alloy. And it is the way that the buttweld fittings are having many properties like corrosion resistance, great ductility, high tensile strength, and others.
| STANDARD | UNS | WNR. | AFNOR | EN | JIS | BS | GOST |
|---|---|---|---|---|---|---|---|
| SS 309 | S30900 | 1.4833 | - | - | - | - | - |
| SS 310 | S31000 | 1.4841 | - | X2CrNi18-9 / X2CrNi19-11 | SUS 310 | 310S24 | 20Ch25N20S2 |
| SS 310S | S31008 | 1.4845 | - | X8CrNi25-21 | SUS 310S | 310S16 | 20Ch23N18 |
SS 316 is the austenitic alloy steel that is used in the development of the buttweld fittings. However, the SS 316 is containing many alloying elements with which they are used in the industries. SS 316L is the low carbon version of the alloy grade 316 this is the best used in the industrial applications which are used in the high-temperature environments. With the modified version of the alloy, the SS 316Ti is used in the development of the buttweld fittings.
Thus, with the presence of the alloy stainless steel, the SS 316/316L/316Ti Buttweld Fittings is inheriting several properties. Some of the properties which are there with the buttweld fittings are great ductility, durability, high tensile strength, great toughness, and stability in the elevated temperatures.
| STANDARD | UNS | WNR. | AFNOR | EN | JIS | BS | GOST |
|---|---|---|---|---|---|---|---|
| SS 316 | S31600 | 1.4401 / 1.4436 | Z7CND17‐11‐02 | X5CrNiMo17-12-2 / X3CrNiMo17-13-3 | SUS 316 | 316S31 / 316S33 | - |
| SS 316L | S31603 | 1.4404 / 1.4435 | Z3CND17‐11‐02 / Z3CND18‐14‐03 | X2CrNiMo17-12-2 / X2CrNiMo18-14-3 | SUS 316L | 316S11 / 316S13 | 03Ch17N14M3 / 03Ch17N14M2 |
| SS 316Ti | S31635 | 1.4571 | Z6CNDT17‐123 | X6CrNiMoTi17-12-2 | SUS 316Ti | 320S31 | 08Ch17N13M2T |
SS 317L is the low carbon version of the alloy which is the modified version of grade 317 stainless steel. This alloy is having high strength properties along with the corrosion resistance with the presence of the carbon contents. But with the low carbon content produce stronger welds with the presence of the 317-grade alloy.
SS 317/317L Buttweld Fittings is available with holding several properties. However, some of the properties which the buttweld fittings are holding are great ductility, high tensile strength, strong toughness, stability in the elevated temperatures, and great corrosion resistance ability. It is the way that the fittings are used in industrial applications.
| STANDARD | UNS | WNR. | EN | JIS |
|---|---|---|---|---|
| SS 317 | S31700 | 1.4449 | - | SUS 317 |
| SS 317L | S31703 | 1.4438 | X2CrNiMo18-15-4 | SUS 317L |
The buttweld fitting has many specifications and features which are very useful in all sorts of industries and different productions. The SS 321/321H Buttweld Fittings specific are ASTM A403 / ASME SA403 with respect to its size which is 1/8” NB TO 48” NB that is very seamless and 100% welded with fabrications also. The mentioned standards of this buttweld fitting are ASME/ANSI B16.9, ASME B16.28, and MSS-SP-43. And this also represents that the product is very seamless, fabricated and welded. The tensile strength is Psi – 75000, MPa – 515. Here the company provides the best in the class testing certificate to all the products. Some of the test certificates for the product SS 321/321H Buttweld Fittings are the raw material certificate, the inspection report of the third party and also has 100% radiologist report.
| STANDARD | UNS | WNR. | EN | JIS |
|---|---|---|---|---|
| SS 321 | S32100 | 1.4541 | X6CrNiTi18-10 | SUS 321 |
| SS 321H | S32109 | 1.4878 | X12CrNiTi18-9 | SUS 321H |
Such products are used in numerous applications or industries because the production value on all these elements is very refined, which means that every product is been made, tested and used for a specific purpose only. All the parameters are been checked and analyzed then only the SS 347/347H Buttweld Fittings is launched. Thus it has several features which inherently make very sense like it is heat resistant, craved with excellent conductivity, rust-free, improved life cycle and all these are been carried out with the specifications like ASTM A403 / ASME SA403, with dimension of ASME/ANSI B16.9, ASME B16.28, MSS-SP-43 and bending radius of R=1D, 2D, 3D, 5D, 6D, 8D, 10D or Custom.
| STANDARD | UNS | WNR. | EN | JIS | GOST |
|---|---|---|---|---|---|
| SS 347 | S34700 | 1.4550 | X6CrNiNb18-10 | SUS 347 | 08Ch18N12B |
| SS 347H | S34709 | 1.4961 | X6CrNiNb18-12 | SUS 347H | - |
The range of the products is numerous and similarly, the list of buyers is also there so provide all of them with their own desired product is necessary. The SS 904L Buttweld Fittings has different standards and specifications that are true features also like its main specification that is very important is ASTM B366 / ASME SB366. Therefore it is based on the standards of ASME/ANSI B16.9, ASME B16.28, and MSS-SP-43. All these are based on certain standards and protocol this is because a particular protocol is necessary to make these products without it the product would not reach its end-stage. Even the size is also kept in standard terms which are 1/8” NB TO 48” NB and the type is both fabricated and seamless.
| STANDARD | WERKSTOFF NR. | UNS | JIS | KS | BS | AFNOR | EN |
|---|---|---|---|---|---|---|---|
| SS 904L | 1.4539 | N08904 | SUS 904L | STS 317J5L | 904S13 | Z2 NCDU 25-20 | X1NiCrMoCu25-20-5 |
