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Stainless Steel Seamless Pipes
Stainless steel seamless pipes (SMLS pipes) are joint-free pipes made to ASTM A312 / ASME SA312, available in grades TP304 to TP347 and sizes 1/8" to 24" NB. Solitaire Overseas manufactures and exports seamless SS pipe worldwide with full mill test certification.
What Are Stainless Steel Seamless Pipes?
Stainless steel seamless pipes, also called SMLS pipes or seamless ss pipes are hollow, joint-free cylinders produced by hot-rolling or cold-drawing a solid billet. Because there is no weld seam, every stainless seamless pipe delivers uniform wall thickness, superior burst-pressure resistance and outstanding resistance to corrosion and high temperatures. Manufactured to ASTM A312 / ASME SA312, they are the preferred choice for fluid transportation, heat exchangers, boilers and pressure vessels across demanding industries worldwide.
Unlike welded pipes, SMLS pipes carry no heat-affected zone (HAZ) along the pipe wall, making them ideal wherever fatigue, cyclic loading, or aggressive media would compromise a weld seam. Available in schedules from SCH 5S to SCH 160 and XXS and in grades from TP304 to TP347, our stainless steel seamless pipes cover virtually every industrial specification.
How Seamless Pipe Is Made
Producing a true seamless ss pipe starts with a solid round billet, which is pierced and elongated over a mandrel under heat to form a hollow shell, then hot-rolled or cold-drawn to final dimensions. A solution annealing step follows to restore corrosion resistance and relieve internal stress introduced during forming, before the pipe is pickled and passivated to remove surface scale. This process as opposed to rolling and welding a flat strip is what eliminates the weld seam entirely and gives the seamless pipe its dimensional uniformity and higher pressure rating compared to welded construction.
Stainless Steel Seamless Pipe Manufacturer, Supplier & Exporter in India
Solitaire Overseas is a stainless steel seamless pipe manufacturer in India with a reputation for precision-engineered piping solutions delivered to critical industrial projects on every continent. As a trusted seamless ss pipe supplier in Mumbai, we stock finished pipe ready for immediate dispatch, backed by a global logistics network that makes us a competitive stainless steel seamless pipe exporter in India.
Our pipes are produced from solid stainless steel billets with no welded joints ensuring high strength, uniform structural properties, and maximum resistance to pressure, temperature, and corrosion. We serve the oil & gas, petrochemical, power generation, pharma, food-grade, and heavy-engineering sectors, where operational reliability is non-negotiable.
ASTM A312 / ASME SA312 | EN 10216 / ANSI B36.19 | Mill Test Certificate 3.1 / 3.2 | ISO-Certified QMS | Hydrostatic & NDT Tested
Looking to buy Stainless Steel Tubes? Check our SS 304 Tubes, SS 316/316L Tubes, and more. Or explore our Stainless Steel Seamless Tubes range for the tube equivalent of this page.
Stainless Steel Seamless Pipe Grades
We supply SS seamless pipes in a wide range of austenitic stainless steel grades, each selected for specific operating conditions:
- SS 304 Seamless Pipes (ASTM A312 TP304): General-purpose grade with good corrosion resistance and excellent formability; widely used in food processing and industrial piping.
- SS 304L Seamless Pipes (ASTM A312 TP304L): Low-carbon variant offering improved weldability and resistance to intergranular corrosion.
- SS 316 Seamless Pipes (ASTM A312 TP316): Contains molybdenum for enhanced resistance to chlorides and aggressive chemicals; ideal for marine and chemical environments.
- SS 316L Seamless Pipes (ASTM A312 TP316L): Low-carbon version of 316, suitable for high-temperature and corrosive applications requiring post-weld integrity.
- SS 321 Seamless Pipes (ASTM A312 TP321): Titanium-stabilised grade designed for high-temperature service and resistance to carbide precipitation.
- SS 347 Seamless Pipes (ASTM A312 TP347): Columbium/niobium-stabilised; preferred for high-temperature petrochemical service and nuclear applications.
- SS 310/310S Seamless Pipes: High chromium and nickel content provides excellent oxidation resistance at elevated temperatures.
ASTM A312 Stainless Steel Seamless Pipe Specifications
Our ASTM A312 SMLS pipes and ASME SA312 stainless seamless pipe are available in the following configurations:
| Specification | Details |
|---|---|
| Standards | ASTM A312, ASME SA312, ASTM A213, EN 10216-5, ANSI B36.19 |
| Material | Stainless Steel (Austenitic, Duplex, Super Duplex) |
| Sizes | 1/8" NB to 24" NB (Nominal Bore) |
| Outer Diameter | 6.35 mm to 609.6 mm |
| Wall Thickness / Schedule | SCH 5S, SCH 10S, SCH 40S, SCH 80S, SCH 120, SCH 160, XXS |
| Type | Round, Square, Rectangular, Hydraulic |
| End Finish | Plain End, Bevelled End, Threaded |
| Length | Single Random, Double Random, Cut Length |
| Test Certificates | Mill Test Certificate EN 10204 3.1 / 3.2 |
Stainless Steel Seamless Pipes Standards
Our stainless steel seamless pipes are manufactured and tested in accordance with major international standards:
| Standard | Description |
|---|---|
| ASTM A312 / ASME SA312 | Seamless, welded, and heavily cold-worked austenitic stainless steel pipes — the primary standard for ASTM A312 SMLS pipe |
| ASTM A213 | Seamless ferritic and austenitic alloy-steel tubes for boilers and heat exchangers |
| ASTM A269 | Seamless and welded stainless steel tubing for general service |
| EN 10216-5 | European standard — seamless pipe EN 10216 stainless for pressure purposes |
| ANSI B36.19 | Stainless steel pipe dimensions and schedules (SCH 5S to XXS) |
| ASTM A106 | Seamless carbon steel pipe for high-temperature service (compatible applications) |
Chemical Composition of SS Seamless Pipes
| Grade | UNS No. | C (max) | Mn (max) | Cr | Ni | Mo |
|---|---|---|---|---|---|---|
| TP304 | S30400 | 0.08 | 2.0 | 18.0–20.0 | 8.0–11.0 | — |
| TP304L | S30403 | 0.035 | 2.0 | 18.0–20.0 | 8.0–13.0 | — |
| TP316 | S31600 | 0.08 | 2.0 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 |
| TP316L | S31603 | 0.035 | 2.0 | 16.0–18.0 | 10.0–14.0 | 2.0–3.0 |
| TP321 | S32100 | 0.08 | 2.0 | 17.0–19.0 | 9.0–12.0 | — |
| TP347 | S34700 | 0.08 | 2.0 | 17.0–20.0 | 9.0–13.0 | — |
Mechanical Properties of Seamless SS Pipes
| Grade | Tensile Strength (MPa, min) | Yield Strength (MPa, min) | Elongation (%, min) | Hardness (HRB, max) |
|---|---|---|---|---|
| TP304 | 515 | 205 | 40 | 92 |
| TP304L | 485 | 170 | 40 | 92 |
| TP316 | 515 | 205 | 40 | 95 |
| TP316L | 485 | 170 | 40 | 95 |
| TP321 | 515 | 205 | 40 | 95 |
| TP347 | 515 | 205 | 40 | 95 |
Stainless Steel Seamless Pipe Dimensions & Sizes
Solitaire Overseas offers stainless steel seamless pipes including large diameter seamless pipes and thick wall seamless pipes across a comprehensive range of sizes and schedules:
| Parameter | Range / Details |
|---|---|
| Outside Diameter (OD) | 6 mm NB to 600 mm NB |
| Schedules | SCH 5S, SCH 10S, SCH 40, SCH 80, SCH 120, SCH 160, XXS |
| Wall Thickness | As per ASTM A312 / ANSI B36.19 and customer requirements |
| Large Diameter Range | 10" to 24" NB (SCH 10S to SCH 80S available) |
| Thick Wall / High-Pressure | SCH 160 & XXS; custom heavy-wall on request |
| Length | Random, double random, or cut lengths |
Custom sizes, tight tolerances, and special finishes can be supplied on request.
ASTM A312 SS Seamless Pipe Schedule Chart
Use the schedule chart below to select the correct wall thickness and seamless pipe pressure rating for your system:
| Nominal Pipe Size (NPS) | Commonly Available Schedules |
|---|---|
| 1/8" to 3/4" | SCH 10S, SCH 40S, SCH 80S |
| 1" to 2" | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
| 2 1/2" to 3" | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
| 4" | SCH 5S, SCH 10S, SCH 40 stainless steel seamless pipe, SCH 80S |
| 6" | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
| 8" | SCH 5S, SCH 10S, SCH 40S, SCH 80S, SCH 120, SCH 160 stainless steel seamless pipe |
| 10" to 12" | SCH 5S, SCH 10S, SCH 40S, SCH 80S |
| 14" to 24" | SCH 10S, SCH 40S (STD), SCH 80S (XS) |
Choosing the right schedule is a pressure-rating decision as much as a dimensional one; a heavier schedule at the same NPS raises the working pressure the pipe can hold. If you're unsure which schedule fits your design pressure and temperature, share your process conditions with our team and we'll confirm the right selection.
Stainless Steel Seamless Pipe Weight Chart (Per Meter)
| NPS (inch) | OD (mm) | Wall Thickness (mm) | Schedule | Weight (kg/m) |
|---|---|---|---|---|
| 1/2" | 21.3 | 2.77 | 40S | 1.29 |
| 1/2" | 21.3 | 3.73 | 80S | 1.65 |
| 3/4" | 26.7 | 2.87 | 40S | 1.71 |
| 3/4" | 26.7 | 3.91 | 80S | 2.23 |
| 1" | 33.4 | 3.38 | 40S | 2.54 |
| 1" | 33.4 | 4.55 | 80S | 3.29 |
| 1 1/2" | 48.3 | 3.68 | 40S | 4.11 |
| 1 1/2" | 48.3 | 5.08 | 80S | 5.49 |
| 2" | 60.3 | 3.91 | 40S | 5.52 |
| 2" | 60.3 | 5.54 | 80S | 7.60 |
| 3" | 88.9 | 5.49 | 40S | 11.47 |
| 3" | 88.9 | 7.62 | 80S | 15.51 |
| 4" | 114.3 | 6.02 | 40S | 16.32 |
| 4" | 114.3 | 8.56 | 80S | 22.67 |
| 6" | 168.3 | 7.11 | 40S | 28.69 |
| 6" | 168.3 | 10.97 | 80S | 43.21 |
| 8" | 219.1 | 8.18 | 40S | 43.20 |
| 8" | 219.1 | 12.70 | 80S | 65.63 |
Stainless Steel Seamless Pipe Price in India
Stainless steel seamless pipe price in India varies depending on grade (SS 304, 316L, 321, 347), schedule (SCH 40 to SCH 160), diameter (NB 1/2" to 24"), and order quantity. As a manufacturer and direct exporter, Solitaire Overseas offers competitive ex-works and CIF pricing with no intermediary margins.
Key price factors:
- Grade: TP304/304L prices are lowest; TP316L, TP321, and TP347 carry a premium.
- Schedule / Wall Thickness: Heavier schedules (SCH 80, SCH 160, XXS) consume more material.
- Diameter: Large diameter seamless pipes above 8" NB are priced by weight (kg).
- Quantity: Bulk mill orders attract significantly better rates than spot purchases.
- Certifications: MTC 3.2 / third-party inspection add a modest premium.
Contact our sales team for a mill-direct price list, updated monthly based on LME nickel and stainless coil indices.
HS Code for Stainless Steel Seamless Pipe
Correct HS (Harmonized System) classification is essential for customs clearance, duty calculation, and export/import documentation when sourcing stainless steel seamless pipes internationally. The table below gives the internationally standardized 6-digit HS codes that apply to seamless stainless steel tubes and pipes:
| HS Code | Description |
|---|---|
| 7304.11 | Line pipe of a kind used for oil or gas pipelines, seamless, of stainless steel |
| 7304.21 | Casing and tubing of a kind used in drilling for oil or gas, seamless, of stainless steel |
| 7304.41 | Other tubes, pipes and hollow profiles, seamless, of circular cross-section, of stainless steel, cold-drawn or cold-rolled |
| 7304.49 | Other tubes, pipes and hollow profiles, seamless, of circular cross-section, of stainless steel, not cold-drawn or cold-rolled (hot-finished) |
National customs authorities extend the international 6-digit HS code with additional digits for their own tariff schedules (for example, India's ITC-HS 8-digit system, or the EU's 10-digit TARIC system). The exact 8-10 digit code depends on your destination country, the pipe's exact finish (cold-drawn vs. hot-finished), and end use. Always confirm final classification with your customs broker or Chartered Engineer before filing import/export documentation — we're happy to share the classification we use on our own shipments as a reference point.
Need the classification for a specific shipment? Contact our team with your destination country and we'll confirm the code we use on export documentation.
Seamless Pipe vs Welded Pipe — Which Should You Choose?
Understanding the difference between seamless pipe vs welded pipe helps engineers select the right product for their pressure class and application:
Seamless SS Pipe (SMLS)
- No weld seam — uniform strength throughout
- Higher pressure and temperature ratings
- Superior fatigue and cyclic-load resistance
- Required for oil & gas, boiler, and nuclear codes
- Preferred where Mill Test Certificate and full traceability are mandatory
Welded SS Pipe (ERW / TIG)
- Lower cost for large diameters and standard services
- Weld seam may be a stress concentration point
- Suitable for low-pressure structural and non-critical service
- Faster availability in non-standard sizes
- Not accepted under many high-pressure piping codes
Rule of thumb: Specify ASTM A312 SMLS pipe (seamless) for pressures above 150 bar, temperatures above 300°C, or wherever code compliance (ASME B31.3, B31.1) demands it. Use welded for low-pressure utility service.
Applications of Stainless Steel Seamless Pipes
- Oil & Gas Industry: Used in upstream, midstream, and downstream operations for transporting hydrocarbons, high-pressure fluids, and gases under extreme conditions. SCH 80 and SCH 160 grades are standard for downhole and Christmas-tree assemblies.
- Petrochemical & Chemical Processing: Ideal for handling corrosive chemicals, acids, and solvents in reactors, heat exchangers, and processing pipelines. TP316L and TP317L grades dominate chloride-rich environments.
- Power Generation: Used in boilers, superheaters, economisers, and steam pipelines where high temperature and pressure resistance is required. ASTM A213 TP321 and TP347 are specified for creep-sensitive zones.
- Pharmaceutical & Food Grade: TP316L with electropolished or Ra ≤ 0.4 µm interior finishes meets FDA, EHEDG, and GMP hygiene requirements for CIP/SIP systems and sterile product transfer lines.
- Industrial & Mechanical Applications: Applied in hydraulic systems, pressure vessels, and high-stress mechanical components where thick-wall seamless pipe ensures safety margins.
Why Choose Solitaire Overseas?
- Premium raw materials with strict manufacturing controls ensure batch-to-batch consistency.
- Complete coverage of grades, sizes, and schedules — SS 304 to SS 347, SCH 5S to SCH 160 / XXS.
- Global supply to Middle East, Europe, Asia, Africa, and the Americas from our Mumbai warehouse.
- Bulk sourcing and mill-direct procurement allow competitive SS seamless pipe pricing.
- Fast technical support and customised solutions for EPC contractors and end users.
- Every pipe supplied with Mill Test Certificate (EN 10204 3.1 / 3.2) for full traceability.
SS Seamless Pipes Export & Quality Certifications
All stainless steel seamless pipes supplied by Solitaire Overseas undergo rigorous inspection and testing, including:
- Chemical composition analysis (PMI / spectrometer)
- Mechanical testing (tensile, yield, elongation)
- Hydrostatic and non-destructive testing (UT / ET)
- Dimensional and visual inspection per ASTM / EN
MTC EN 10204 3.1 | MTC EN 10204 3.2 (TPI) | ASTM A312 Compliant | ASME SA312 Compliant | EN 10216-5 | ISO-Certified QMS
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Frequently Asked Questions — Seamless Stainless Steel Pipe
A seamless ss pipe (SMLS pipe) is manufactured from a solid round billet without any welded joints. The extrusion and drawing process ensures high strength, dimensional uniformity, and superior pressure resistance, making it the preferred choice for critical industrial applications including oil & gas, power, and chemical processing.
Seamless pipes are made from a single solid billet with no joints, no heat-affected zone, higher pressure ratings, and full compliance with ASME B31.3 high-pressure requirements. Welded pipes are formed from rolled sheet with a longitudinal weld; they are more cost-effective for low-pressure utility service but cannot match the structural integrity of SMLS pipe under cyclic or extreme-temperature loading.
The seamless pipe pressure rating depends on grade, OD, and wall thickness schedule. For example, a 2" NB ASTM A312 TP316L pipe in SCH 80S has a working pressure of approximately 177 bar at ambient temperature, while SCH 160 and XXS schedules achieve significantly higher ratings.
ASTM A312 is the ASTM International standard covering seamless (SMLS), welded, and heavily cold-worked austenitic stainless steel pipes. The SMLS designation confirms the pipe was produced without a weld seam. The companion ASME standard is SA312, used in pressure vessel and boiler code compliance.
ASTM A312 TP316L seamless pipe is the most-requested grade for corrosive service. It contains 2–3% molybdenum for chloride resistance and a maximum 0.035% carbon to prevent sensitisation. We also stock ASTM A312 TP304, TP321, and TP347 seamless pipes for high-temperature and stabilised-grade applications.
Yes. We supply seamless stainless steel pipe for pharma and food-grade applications in TP316L with electropolished internal surfaces (Ra ≤ 0.4 µm or 0.8 µm) per DIN 11850 / ISO 2037. These pipes meet FDA, EHEDG, and 3-A Sanitary Standards for CIP/SIP and sterile process lines.
High-quality SMLS pipes can last 20–50 years or more, depending on material grade, operating conditions, and maintenance. Correct grade selection for example TP316L in chloride environments or TP321 in high-temperature service is the primary factor in achieving maximum service life.
Yes. Every order is supplied with a Mill Test Certificate (MTC) as per EN 10204 3.1 as standard. Third-party 3.2 inspection by TÜV NORD, Bureau Veritas, SGS, or Lloyd's Register is available on request.
Stainless seamless pipe (ASTM A312) is specified by nominal pipe size (NPS) and schedule, and is the standard choice for pressure piping systems. Seamless tube (ASTM A213/A269) is specified by exact outer diameter and wall thickness, and is more common in heat exchangers and instrumentation where tighter dimensional tolerance matters more than matching a pipe schedule.