Metinox Overseas is a major supplier and manufacturer of SS 310S Pipe Fittings in India, which is used by engineering contractors, EPC companies as well as industrial procurement teams worldwide. Our ASTM A403 WP310S fittings are manufactured according to rigid quality control measures and can be supplied with complete material traceability, EN 10204 3.1 Mill Test Certificates and with the third-party inspection.
The low-carbon version of the standard 310 grade is stainless Steel 310S. It has a maximum carbon content of C 0.08% max as opposed to 0.25 C 0.08 max in regular SS 310. This is the critical reduction that occurs to remove the carbide precipitation at weld heat-affected zones (HAZ) which is the leading cause of sensitization and intergranular corrosion in high-temperature welded assemblies. The outcome is high weldability with no loss in oxidation resistance that caused 310-series stainless steels to be the most preferred choice in high temperature service.
The 25Cr-20Ni chemistry, the same oxidation resistance to 1040 deg C continuous service and high-temperature mechanical strength of standard 310 are retained, and the weld sensitization immunity of SS 310 S Pipe Fittings is complete. In the case of manufactured furnace internal, heat exchanger, muffles, kilns and food processing equipment, SS 310S is the commercially favored technically superior material.
Browse our full range of Stainless Steel Pipes and Tubes to complement your SS 310S Pipe Fittings procurement.
| Property | Value | Property | Value |
|---|---|---|---|
| Standard | ASTM A403 WP310S | Grade | WP310S |
| UNS Number | S31008 | DIN Number | 1.4845 |
| Werkstoff | 1.4845 | JIS Equivalent | SUS 310S |
| Finish | Seamless / Welded | NB Range | 1/2 inch to 48 inch |
| Schedule Range | SCH 5S to XXS | Dimensions | ASME B16.9 / B16.28 |
| Delivery Form | Elbow, Tee, Reducer, Cap, Stub End, Cross, Bend | Testing | EN 10204 3.1 / Mill TC |
Carbon content is the single most important technical difference between SS 310 and SS 310S. Carbon is allowed to 0.25 percent in standard 310. Welding of this alloy causes the carbon to move to grain boundaries within the heat affected zone and mix with chromium to form chromium carbides. This is referred to as sensitization and leaves the area located directly around welds devoid of chromium and exposes them to intergranular corrosion and high temperature accelerated oxidation. In fabricated assemblies, which undergo thermal cycling, the outcomes may be premature failure, leakage, and unwanted costs of shutdown.
SS 310S Pipe Fittings deal with this issue on the material level. There is no serious carbon remaining to form major chromium carbide at weld boundaries due to the carbon remaining at 0.08% max. The outcome is total resistance to weld sensitization and that is why ASTM A403 WP310S is the grade of choice of any piping system or high temperature assembly that requires site welding, field fabrication or factory-built welded modules.
The three core reasons engineers specify SS 310S Pipe Fittings are:
Notably, the performance trade-off is not involved in selecting SS 310S Pipe Fittings. Oxidation resistance to 1040 deg C continuous (and 900 deg C intermittent) is the same as standard 310. Tensile and yield strength are the same properties. Composition is identical 24 to 26 per cent. chromium and 19 to 22 per cent. nickel. The carbon maximum is all that varies, and the variation eradicates the one greatest risk in high-temperature piping assemblies welded.
The table below covers every critical decision point for buyers choosing between standard SS 310 and SS 310S Pipe Fittings. Both grades are manufactured to ASTM A403 but carry different WP designations and suit different fabrication methods.
| Property | SS 310 | SS 310S | Buyer Insight |
|---|---|---|---|
| Carbon Content | Max 0.25% | Max 0.08% | 310S has 68% less carbon |
| Carbide Precipitation at Welds | High risk | Eliminated | 310S is immune to sensitization |
| Weldability | Moderate | Superior | 310S is preferred for welded assemblies |
| Chromium Content | 24 to 26% | 24 to 26% | Identical in both grades |
| Nickel Content | 19 to 22% | 19 to 22% | Identical in both grades |
| Max Continuous Service Temp | 1040 deg C | 1040 deg C | No performance trade-off |
| Max Intermittent Service Temp | 900 deg C | 900 deg C | Same for both grades |
| Oxidation Resistance | Excellent | Excellent | No difference |
| Sensitization Risk in HAZ | Present | None | 310S is the safe choice |
| Preferred For | Bolted / non-welded assemblies | Welded fabricated assemblies | Choose based on fabrication method |
| ASTM Standard | A403 WP310 | A403 WP310S | Different grade designations |
For buyers comparing standard and low-carbon grades, see our SS 310 Pipe Fittings Standard Grade page for the full 310 specification, size range, and pricing details.
Metinox Overseas stocks and supplies the complete range of SS 310S Buttweld Fittings to ASME B16.9 and ASME B16.28. All fitting types are available in seamless (WP-S) and welded (WP-W) construction across the full size range from 1/2 inch to 48 inch NB.
The 90 Degree LR Elbow in SS 310S changes flow direction by 90 degrees with a centreline radius of 1.5 times the nominal pipe diameter. It is the most commonly specified elbow type for furnace interconnecting piping, heat exchanger headers, and high-temperature chemical plant where smooth, low-turbulence flow transitions are required alongside full weldability at joints.
The 45 Degree Elbow provides a gentler directional change than the 90 Degree type and is used where space allows a gradual transition or where pressure drop minimisation is important. Available in both long radius and, for tight-run pipework, short radius configurations.
The 180 Degree Return Bend (also called U-bend) reverses flow direction completely within a compact loop. It is widely used in fired heater coils, thermal oxidiser circuits, heat exchanger shells, and recuperator tubes where the piping must make a complete reversal within limited space.
The SS 310S Equal Tee connects three pipes of the same nominal bore. It allows branching at 90 degrees to the main run and is manufactured to ASME B16.9 dimensional standards. With C 0.08% max chemistry, all three welded joints retain full sensitization immunity after assembly.
The Reducing Tee accommodates a branch of a smaller nominal bore than the main run. It is specified in distribution systems where process lines split into secondary circuits of reduced size. Available across a wide range of run/branch combinations in the Metinox Overseas stock programme.
The Concentric Reducer transitions between two pipe bores in a straight, symmetrical cone. Both the inlet and outlet centrelines are aligned. It is used in vertical pipe runs and in horizontal lines where the pipe must remain level along its centreline.
The Eccentric Reducer transitions between two pipe bores with the centrelines offset. The flat side allows the pipe invert (bottom) to remain level, preventing liquid accumulation in lines that handle mixed-phase or liquid-carrying service. Frequently specified in pump suction lines.
The SS 310S End Cap is a hemispherical or dished closing fitting welded to the open end of a pipe to seal it permanently. It is used to terminate dead legs, blind off test connections, and cap open branch ends in high-temperature systems.
Stub Ends (long and short pattern per ASME B16.9) are used in conjunction with backing flanges to create a lap joint connection. The stub end is welded to the pipe, and a loose backing flange passes over it. This arrangement allows the backing flange to be made from a lower-cost material while the wetted stub end remains in premium SS 310S. Popular in food processing and pharmaceutical piping for its ease of disassembly and alignment.
The SS 310S Cross provides four-way flow distribution from a single fitting body. It connects four pipes at right angles, with two run ends and two branch ends. Used in complex distribution manifolds where two branch connections are required from a single point.
Custom radius bends in 3D and 5D configurations (centreline radius equal to 3 and 5 times the pipe diameter respectively) provide sweeping, low-pressure-drop directional changes for process lines. They are particularly useful in fired heater circuits, reformer piping, and any line where flow velocity makes standard short-radius elbows unacceptable.
| Carbon (C) | Chromium (Cr) | Nickel (Ni) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) |
|---|---|---|---|---|---|
| 0.08% max | 24.00 to 26.00% | 19.00 to 22.00% | 2.00% max | 1.50% max | 0.045% max |
| Sulfur (S) | Iron (Fe) | UNS | DIN | Werkstoff | JIS |
|---|---|---|---|---|---|
| 0.030% max | Balance | S31008 | 1.4845 | 1.4845 | SUS 310S |
The low carbon maximum of 0.08% in SS 310S Pipe Fittings (UNS S31008 / DIN 1.4845 / WERKSTOFF 1.4845) is the defining feature that distinguishes this grade from standard SS 310. All other elemental ranges are identical. The high chromium content (24 to 26%) provides outstanding oxidation resistance while the high nickel content (19 to 22%) ensures structural stability and prevents sigma phase formation during long-term high-temperature service.
| Property | Metric Value | Imperial Value | Condition |
|---|---|---|---|
| Tensile Strength | 515 MPa min | 75 ksi min | Annealed |
| Yield Strength (0.2% offset) | 205 MPa min | 30 ksi min | Annealed |
| Elongation in 2 inches | 30% min | 30% min | Annealed |
| Hardness (Brinell) | 217 HB max | 217 HB max | Annealed |
| Density | 7.9 g/cm³ | 0.285 lb/in³ | Room Temp |
| Standard | Grade Designation | Standard | Grade Designation |
|---|---|---|---|
| ASTM / ASME | UNS S31008 | DIN (Germany) | 1.4845 |
| Werkstoff Nr | 1.4845 | JIS (Japan) | SUS 310S |
| EN (Europe) | X8CrNi25-21 | BS (UK) | 310S24 |
| ISO | X6CrNi25-21 | Chinese Standard | 06Cr25Ni20 |
| Parameter | Range / Description | Parameter | Range / Description |
|---|---|---|---|
| Nominal Bore (NB) | 1/2 inch to 48 inch | DN Range | DN 15 to DN 1200 |
| Wall Thickness (Schedule) | SCH 5S, 10S, 20, 40S (STD), 80S (XS), 160, XXS | End Type | BW (Buttweld) per ASME B16.9 |
| Elbow Radius | 1.5D Long Radius (LR) and 1D Short Radius (SR) | Bend Types | 3D, 5D, 7D, 10D |
| Fitting Types Available | Elbow, Tee, Reducer, Cap, Stub End, Cross, Return Bend | Material Form | Seamless (WP-S) and Welded (WP-W / WP-WX) |
The following table provides representative weights for SS 310S 90 Degree Long Radius Elbows across common NB sizes and schedules. Weights for other fitting types and schedules are available on request. All dimensions per ASME B16.9.
| NB (DN) | OD (mm) | Schedule | Wall (mm) | Fitting Type | Approx Weight | Standard |
|---|---|---|---|---|---|---|
| 1/2" (15) | 21.3 mm | SCH 40S | 2.77 mm | 90 deg LR | ~0.04 kg | ASME B16.9 |
| 1" (25) | 33.4 mm | SCH 40S | 3.38 mm | 90 deg LR | ~0.17 kg | ASME B16.9 |
| 2" (50) | 60.3 mm | SCH 40S | 3.91 mm | 90 deg LR | ~0.68 kg | ASME B16.9 |
| 4" (100) | 114.3 mm | SCH 40S | 6.02 mm | 90 deg LR | ~3.60 kg | ASME B16.9 |
| 6" (150) | 168.3 mm | SCH 40S | 7.11 mm | 90 deg LR | ~9.50 kg | ASME B16.9 |
| 8" (200) | 219.1 mm | SCH 40S | 8.18 mm | 90 deg LR | ~18.40 kg | ASME B16.9 |
| 10" (250) | 273.1 mm | SCH 40S | 9.27 mm | 90 deg LR | ~31.50 kg | ASME B16.9 |
| 12" (300) | 323.9 mm | SCH 40S | 9.53 mm | 90 deg LR | ~45.00 kg | ASME B16.9 |
Note: Weights listed are approximate and are for reference only. Actual weights may vary based on manufacturing tolerances, raw material heat, and schedule combination. Contact Metinox Overseas for certified weight and dimension data sheets for your specific order.
The combination of low carbon chemistry, superior weldability, and 1040 deg C oxidation resistance makes SS 310S Pipe Fittings the material of choice across a wide range of demanding industries. Below are the primary application sectors and the specific reasons SS 310S is specified.
Many industries furnaces, continuous belt furnaces, and box muffles often operate at service temperatures in excess of 900 deg C. All interconnecting piping, headers and manifolds containing combustion gas, process gas, or inert atmosphere inside or outside furnace chambers are specified in SS 310S Pipe Fittings (ASTM A403 WP310S). The low carbon levels also assure that repeated thermal cycle between ambient and operating temperature does not sensitize weld joints with time.
Rotary kilns that are applied in cement, lime and mineral processing work at high temperatures that are sustained with aggressive carburizing and oxidizing environments. The carburizing resistance and oxidation resistance requirements to sustain service life in such environments are provided by SS 310S Pipe Fittings. The 25Cr content gives a dense (self-repairing) Cr2O3 scale which shields the base metal against oxidation and carburization.
Chemical processing, petrochemical plants, and power plants are examples of heat exchangers that are fitted with welded headers, return bends, and connecting fittings. Where operating temperatures are above 650 deg C, SS 310S Pipe Fittings are chosen as opposed to standard 310 since site welding in the absence of risk sensitization is a critical consideration. The standard specification of this duty is ASTM A403 WP310S fittings of UNS S31008 chemistry.
The piping of hydrogen sulphide-containing gas streams, sulphur recovery units (SRUs), and Claus plant piping must have high temperature, corrosion-resistant fittings. SS 310S Pipe Fittings are stronger against attack by hydrogen sulphide compared to the lower-alloy grades. Furthermore, the weldability advantage is of great importance in large bore field-fabricated piping in chemical plants where piping made with standard 310 would result in the introduction of sensitized areas at each joint.
Food and pharmaceutical industries sterilisation tunnels, pasteurisation lines and thermal processing equipment use high temperatures and have a high level of hygiene standards. The optimum choice is SS 310S Pipe Fittings, especially the stub ends that are employed with loose backing flanges since the low carbon content of the fittings will not cause the weld integrity to be compromised with time as the equipment is used.
The piping of waste gas thermal oxidisers and industrial incinerators must be able to resist the high temperature of combustion as well as the corrosive by-products of oxidation of the waste streams. The required service life in the given applications is provided by SS 310S Pipe Fittings (DIN 1.4845 / WERKSTOFF 1.4845), which do not show the sensitization risk as standard 310 would do at the weld joints.
SS 310S Pipe Fittings are one part of a complete SS 310S product family available from Metinox Overseas. Procurement teams can source the entire system from a single supplier, ensuring consistent chemistry, heat traceability, and documentation across all components.
The price of SS 310S Pipe Fittings in India depends on nominal bore size, wall schedule, fitting type, WP designation (seamless or welded), and order quantity. As a rule, SS 310S Pipe Fittings are priced at a premium over standard austenitic grades such as SS 304 or 316, reflecting the higher alloy content (25Cr-20Ni) required for the elevated temperature service these fittings are designed for.
Metinox Overseas offers competitive ex-works and CIF pricing for SS 310S Pipe Fittings across all major export destinations. Standard payment modes include Telegraphic Transfer (T/T), Letter of Credit (L/C) at sight, and documents against payment (D/P). Export packing is in wooden cases or pallet-wrapped bundles with full export documentation including Certificate of Origin, Packing List, Commercial Invoice, and EN 10204 3.1 Mill Test Certificate.
We export SS 310S Pipe Fittings regularly to the UAE, Saudi Arabia, Qatar, Kuwait, Bahrain, Oman, USA, Canada, UK, Germany, Italy, Netherlands, Singapore, Malaysia, Australia, South Africa, and other countries. Our logistics team handles freight, customs documentation, and third-party inspection coordination.
The major difference between SS 310 and SS 310S Pipe Fittings is the highest carbon content. SS 310 allows up to 0.25% carbon while SS 310S limits carbon to 0.08% max. This reduced carbon content in 310S does not allow the precipitation of carbide in areas of the weld heat-affected, which is the elimination of sensitization, making 310S the best grade in any welding application. The other properties, such as oxidation resistance to 1040 deg C, chromium content (24 to 26%), and nickel content (19 to 22%) are the same in the two grades.
The ASTM A403 specification is an American Society of Testing and Materials standard that regulates wrought austenitic stainless steel buttweld pipe fittings. The designation of that specific grade within that specification is WP310S, which denotes the fitting being produced using SS 310S chemistry with carbon content of 0.08% max (UNS S31008). The use of the WP prefix proves the fitting is to be used in welded piping systems. On delivery of a material test certificate of ASTM A403 WP310S fittings, it is a verification of the chemical composition, mechanical properties, heat treatment status, and the dimensional compliance of the supplied fittings.
Most industrial applications do not require post-weld annealing (solution annealing) of SS 310S Pipe Fittings. The low carbon of 0.08% max avoids the sensitization that causes post-weld heat treatment of more carbon-rich grades. But in case of critical pressure service or when the service conditions involve a combination of high temperatures and hostile corrosion environment, then the engineering specification or process code used must be complied with. Welding is to be done with similar chemistry or a somewhat over-alloyed filler metal and standard austenitic stainless steel welding practice is applicable.
Continuous Service The SS 310S Pipe Fittings (UNS S31008, DIN 1.4845) is rated to be continuously operating up to 1040 deg C in oxidising atmospheres. In the case of intermittent service and repeated thermal cycling, the practical maximum temperature is about 900 deg C to prevent the possibility of sigma phase precipitation during the cooling process between 600 and 900 deg C. The effective service limit can be reduced in highly carburizing or reducing conditions and must be compared to the operating chemistry in question. These temperature ratings are the same as standard SS 310, and it is clear that when 310S is selected as a more weldable material, there is no loss in service temperature performance.
Yes Metinox Overseas offers SS 310S Pipe Fittings in seamless construction (WP-S designation) and welded construction (WP-W and WP-WX) in the entire size range of 1/2 inch NB through 48 inch NB. In the case of our Mumbai warehouse, smaller bore fittings can be ex-stock to smaller bore sizes in common schedules. In bigger bore seamless fittings, or unusual schedule combinations, manufacturing lead times are usually between 4 and 8 weeks depending on the mill order and inspection needs. Call our team and get a confirmed lead time and availability check on your size and schedule requirements.
ASTM A403 WP310S | UNS S31008 | DIN 1.4845 | WERKSTOFF 1.4845
1/2" to 48" NB | SCH 5S to XXS | Seamless and Welded | All Fitting Types | EN 10204 3.1 MTC | Export Worldwide
Contact Metinox Overseas for competitive pricing, stock availability, and technical support.
Metinox Overseas provides a full SS 310S product platform to procurement departments requiring single-source supply and regular chemistries traceability. Besides SS 310S Pipe Fittings (ASTM A403 WP310S), we also offer the complete line of SS 310S pipes, tubes and flanges so that all the parts of your system bear the same certification of SS 31008. Explore our complete View all Pipes and Tubes catalogue for a full overview of available grades, sizes, and standards.
Our quality management system includes checking of incoming raw materials, in-processing dimensional inspection, mechanical and chemical tests and final documentation check prior to dispatch. BVIS, SGS, Bureau Veritas and other approved agencies can be inspected third party on request.
To get SS 310S Pipe Fittings pricing, stock, or technical specification questions answered, call our team today. We also reply to any query in a 24 hour period with a formal quote with material availability, lead time and compliance with relevant standards.
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