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Siddhgiri Overseas manufactures stainless steel round pipe in both seamless and welded (ERW) construction, across a grade range spanning SS 202 through 347H, from our facility in Mumbai — a manufacturing base we have operated since 1962. Round pipe is the most widely specified structural and fluid-handling profile in stainless steel because its circular cross-section distributes mechanical and torsional stress evenly around the full circumference, with no localized weak points, while offering a smooth internal bore for efficient flow and a high strength-to-weight ratio compared to solid bar stock. We produce round pipe to both ornamental tubing dimensions and industrial NPS pipe schedules, with dimensional checks carried out before dispatch. This section covers profile selection, sizing conventions, grade options, and typical applications.
Stainless steel round pipe is a circular hollow profile produced by either drawing a solid billet into a seamless tube or by rolling and seam-welding flat strip into a welded (ERW) pipe. The round geometry is not just a shape choice — it is an engineering advantage. A smooth circular bore minimizes turbulence and pressure drop, which matters directly for any application involving fluid or gas flow. Under load, a round cross-section spreads mechanical and torsional stress evenly around its full circumference, so there are no flat faces or corners acting as localized weak points the way there are in square or rectangular tube. This also gives round pipe a high strength-to-weight ratio relative to an equivalent solid round bar, since material is concentrated at the outer radius where it does the most structural work.
Siddhgiri Overseas produces round pipe in both seamless and welded construction, so the profile can be matched to the job — seamless where a continuous, weld-free wall is preferred, welded where the application and standard allow it. For production-method detail on how each type is drawn or rolled, see our separate Seamless Pipe and ERW Pipe pages; this page focuses on the round profile itself — its sizing conventions, grade choices, and where it is used.
Round pipe is sized in two genuinely different ways depending on what it is being used for, and mixing up the two conventions is a common source of ordering errors.
|
Ornamental / Tubing |
ASTM A554 |
Exact outer diameter (e.g. 25.4mm, 38.1mm, 50.8mm) |
Thin wall, 1.0mm to 2.0mm |
Furniture, gates, architectural balustrades |
|
Industrial Pipe |
ASTM A312 / A270 |
Nominal Pipe Size (NPS) — a nominal label, not the literal OD |
Schedule 40 or Schedule 80 |
High-pressure and process fluid containment |
In the ornamental/tubing convention, the quoted size is the actual outer diameter of the pipe. In the industrial NPS convention, the quoted size is a nominal designation rather than a literal dimension — for example, a 2-inch NPS pipe has an actual outer diameter of 2.375 inches. NPS sizing is always paired with a schedule (Schedule 40 or Schedule 80 being the common ranges), which sets the wall thickness for the pressure rating the pipe needs to hold. When specifying round pipe, confirm which convention applies to your application before quoting a size, since a "2-inch" ornamental tube and a "2-inch NPS" pipe are not the same outer diameter.
Siddhgiri Overseas supplies round pipe across the SS 202 to 347H grade range, covering both standard austenitic grades and the budget-oriented 200-series. The table below cross-references the common austenitic grades against their DIN material number, EN designation, and the corresponding ASTM A312 pipe grade.
|
1.4301 |
X5CrNi18-10 |
TP304 |
|
1.4306 |
X2CrNi19-11 |
TP304L |
|
1.4401 |
X5CrNiMo17-12-2 |
TP316 |
|
1.4404 |
X2CrNiMo17-13-2 |
TP316L |
|
1.4541 |
X6CrNiTi18-10 |
TP321 |
|
1.4571 |
X6CrNiMoTi17-12-2 |
TP316Ti |
For dry, indoor, non-corrosive applications where cost is the primary driver, round pipe is also available in SS 202 and SS 201, supplied to ASTM A554 grades MT201 and MT202. These budget grades are best suited to ornamental and furniture-type uses rather than process or outdoor exposure. Every dispatch is accompanied by standard industry documentation, including Mill Test Certificates (MTC), typically issued to EN 10204 3.1, confirming the material supplied against the ordered grade.
Round pipe's profile and grade range put it to work across several distinct industries.
Sanitary pipe — produced to ASTM A270, used in food processing, pharmaceutical, medical, and biochemistry lines where the internal bore must be clean, smooth, and free of contamination-trapping irregularities.
Mechanical and exhaust pipe — produced to ASTM A554/A511, engineered to withstand the thermal fatigue of repeated heating and cooling cycles near exhaust manifolds, holding up under service temperatures up to approximately 900°C without cracking.
Polished architectural pipe — supplied in brushed or mirror-polished finish for handrails, balustrades, and structural trim, where the round profile's smooth surface and even stress distribution suit both the load-bearing and visual requirements of architectural work.
Siddhgiri Overseas is ISO certified for quality, occupational health & safety and environment management, and holds the import and export certification required to supply stainless steel pipe and tube to customers worldwide. Certificate copies are available on request for buyers who need them for their own compliance records.
If the pipe is for furniture, gates, or architectural balustrades where the exact outer diameter matters for fittings and joinery, use ASTM A554 ornamental sizing. If it's for carrying pressurized fluid or gas, use ASTM A312/A270 NPS sizing paired with a schedule (Schedule 40 or 80) that sets the wall thickness for the pressure involved.
Siddhgiri Overseas produces round pipe in both seamless and welded (ERW) construction, and the right choice depends on the application and governing standard rather than the profile itself. See our Seamless Pipe and ERW Pipe pages for a detailed comparison of the two production methods.
NPS (Nominal Pipe Size) is a nominal industry designation, not a literal measurement. For example, a 2-inch NPS pipe has an actual outer diameter of 2.375 inches — the nominal number is a size label used consistently across the industrial piping standard, not the OD itself.
TP304/304L suits general corrosion resistance for most applications, TP316/316L adds molybdenum-based resistance for more demanding environments, and TP321/316Ti are titanium-stabilized grades typically specified where elevated-temperature stability is required. SS 202/201 remain available as a budget option for dry, indoor, non-corrosive use.
Yes. Round pipe produced to ASTM A554/A511 is engineered for mechanical and exhaust applications, handling the thermal fatigue of repeated heating and cooling cycles near exhaust manifolds at service temperatures up to approximately 900°C without cracking.
Polished architectural round pipe is supplied in either a brushed or mirror-polished finish, commonly used for handrails, balustrades, and structural trim where appearance matters alongside strength.
Each dispatch is accompanied by standard industry documentation, including a Mill Test Certificate (MTC), typically issued to EN 10204 3.1, verifying the supplied material against the ordered grade. All pipe also undergoes dimensional checks before dispatch.
