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Siddhgiri Overseas has manufactured stainless steel pipes and tubes from Mumbai since 1962, and our stainless steel tube range is built to the precision tolerances that set tube apart from pipe. Where pipe is sized by nominal bore for carrying fluids and gases, stainless steel tube is produced to a tightly held outside diameter (OD) and wall thickness, giving it the dimensional accuracy needed for structural fabrication, instrumentation, heat exchangers, hydraulic lines and precision machinery. The chromium content in stainless steel forms a passive oxide layer on the surface that resists rust, oxidation and chemical attack, which is why the same tubing works equally well in food-processing lines, pharmaceutical equipment, marine environments and everyday architectural and structural work. Our tube family covers Seamless Tube, drawn without a welded seam for high-pressure and high-temperature duty, Perforated Tube for filtration and screening applications, and a full spread of tube grades including SS 304, SS 304L, SS 316 and SS 316L. Every tube is formed, heat treated, finished and tested before it leaves our facility.
Stainless steel tube is a precision-engineered hollow product available in round, square, rectangular and custom cross-sections. It is built into stainless steel's natural chromium content, which forms a thin, self-repairing oxide layer on the surface — this is what gives the material its resistance to rust, oxidation and chemical attack across a wide range of moisture, temperature and pressure conditions.
What separates tube from other hollow steel products is how it is dimensioned and controlled. Stainless steel tube is manufactured and measured by outside diameter (OD) and wall thickness, held to tight tolerances so the finished product has a predictable, repeatable geometry. That precision is what makes tube suitable for uses where dimensional accuracy matters as much as strength — structural framing, mechanical components, instrumentation lines, and architectural and sanitary installations.
Where stainless steel tube is used
Within this category, Siddhgiri Overseas produces Seamless Tube and Perforated Tube as dedicated product lines, alongside tube in the full range of stainless steel grades covered under Tube Grades.
Producing a stainless steel tube to precise dimensional and mechanical specification involves several controlled stages, from forming through to final inspection.
Production starts from stainless steel coils or billets. Seamless tube is formed by hot extrusion followed by cold drawing to bring it to final dimension. Welded tube is formed by rolling stainless steel strip into a cylindrical shape and joining the seam using TIG welding, laser welding or high-frequency welding, depending on the grade and wall thickness required.
After forming, the tube is annealed under controlled conditions to relieve the internal stresses introduced during forming and welding. Annealing improves ductility, refines the grain structure, and helps restore the material's corrosion resistance and dimensional stability.
Annealed tubes are chemically cleaned and pickled to remove surface oxidation, welding scale and other contaminants, leaving a clean metallic surface that supports better long-term corrosion resistance.
Cold drawing tightens dimensional tolerances further, improves mechanical strength, refines OD and wall thickness, and improves concentricity, while producing a smoother internal and external surface suited to precision engineering applications.
Precision straightening equipment ensures dimensional uniformity along the full length of the tube. Surface finishing is then applied to the customer's requirement — bright annealed, mirror polish, matte, satin, or pickled finish.
Every tube is checked before dispatch. Testing includes:
|
Sized by |
Outside diameter (OD) & wall thickness |
Inside diameter / NPS & schedule |
|
Primary purpose |
Structural, mechanical, precision engineering |
Conveyance of fluids, gases, steam, chemicals |
|
Dimensional tolerance |
Tighter OD tolerance |
Tolerance geared to flow capacity |
|
Cross-section |
Round, square, rectangular, oval, custom |
Round |
|
Typical use |
Instrumentation, heat exchangers, automotive, furniture, architecture |
Piping systems, process lines, utilities |
"Pipe" and "tube" are often used interchangeably, but they are engineered for different jobs and dimensioned in different ways.
Pipe is sized around its inside diameter — specified by Nominal Pipe Size (NPS) and schedule — because its primary function is carrying liquids, gases, steam or chemicals, where flow capacity is what matters. Tube, by contrast, is sized around its outside diameter and wall thickness, because its primary function is structural and mechanical: fitting precisely into an assembly, a fixture, or another component, or performing under load, pressure or heat transfer where exact geometry matters more than bore capacity.
This difference in purpose carries through to manufacturing tolerance and finish. Tube is generally held to a narrower OD tolerance and produced with a smoother internal and external surface than pipe, since it is often used in precision engineering, automotive parts, medical devices and heat exchangers rather than open fluid conveyance. Tube is also available in a wider range of cross-sectional shapes — round, square, rectangular, oval and custom profiles — while pipe is almost always round.
|
Sized by |
Outside diameter (OD) & wall thickness |
Inside diameter / NPS & schedule |
|
Primary purpose |
Structural, mechanical, precision engineering |
Conveyance of fluids, gases, steam, chemicals |
|
Dimensional tolerance |
Tighter OD tolerance |
Tolerance geared to flow capacity |
|
Cross-section |
Round, square, rectangular, oval, custom |
Round |
|
Typical use |
Instrumentation, heat exchangers, automotive, furniture, architecture |
Piping systems, process lines, utilities |
Stainless steel tube performance is driven mainly by the alloy grade selected. Siddhgiri Overseas manufactures tube across the following grades — see Tube Grades for full detail on each.
SS 304
The most widely used stainless steel grade, valued for its corrosion resistance, weldability and formability. Suited to food processing, commercial kitchens, pharmaceutical equipment, architectural work and general industrial fabrication.
SS 304L
A low-carbon version of 304 that reduces carbide precipitation during welding, giving it better weldability for fabricated structures and welded assemblies.
SS 316
Contains added molybdenum for stronger resistance to chlorides, acids and marine environments. Used in chemical processing, pharmaceutical manufacturing, marine engineering, desalination and offshore applications.
SS 316L
The low-carbon version of 316, offering enhanced corrosion resistance and weldability, and commonly specified for hygienic applications, medical devices and high-purity process systems.
Duplex Stainless Steel
A dual ferritic-austenitic structure that gives high mechanical strength and strong resistance to stress corrosion cracking, used in offshore oil and gas facilities, chemical plants and high-pressure industrial systems.
Tube Types
|
Sized by |
Outside diameter (OD) & wall thickness |
Inside diameter / NPS & schedule |
|
Primary purpose |
Structural, mechanical, precision engineering |
Conveyance of fluids, gases, steam, chemicals |
|
Dimensional tolerance |
Tighter OD tolerance |
Tolerance geared to flow capacity |
|
Cross-section |
Round, square, rectangular, oval, custom |
Round |
|
Typical use |
Instrumentation, heat exchangers, automotive, furniture, architecture |
Piping systems, process lines, utilities |
Stainless steel tube from Siddhgiri Overseas is manufactured to recognised international standards and tested before dispatch to confirm it meets them.
|
Material Grades |
SS 304, SS 304L, SS 316, SS 316L, Duplex Stainless Steel |
|
Manufacturing Type |
Seamless & Welded |
|
Tube Shapes |
Round, Square, Rectangular, Custom Profiles |
|
Outside Diameter & Wall Thickness |
As per customer requirement |
|
Length |
Standard & customised lengths |
|
Surface Finish |
Bright Annealed, Mirror Polish, Matte, Satin, Pickled |
|
Manufacturing Standards |
ASTM, ASME, DIN, EN, JIS |
|
Fabrication |
Suitable for welding, cutting and bending |
|
Quality Testing |
Hydro Test, PMI Test, Eddy Current Test, Ultrasonic Test, Visual Inspection, Dimensional Inspection |
Industries We Serve
|
Sized by |
Outside diameter (OD) & wall thickness |
Inside diameter / NPS & schedule |
|
Primary purpose |
Structural, mechanical, precision engineering |
Conveyance of fluids, gases, steam, chemicals |
|
Dimensional tolerance |
Tighter OD tolerance |
Tolerance geared to flow capacity |
|
Cross-section |
Round, square, rectangular, oval, custom |
Round |
|
Typical use |
Instrumentation, heat exchangers, automotive, furniture, architecture |
Piping systems, process lines, utilities |
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.
Pipe is sized by its inside diameter and Nominal Pipe Size (NPS) because its job is to carry fluids, gases, steam or chemicals — flow capacity is what matters. Tube is sized by its outside diameter (OD) and wall thickness because its job is structural or mechanical — fitting precisely into an assembly or performing under load, pressure or heat transfer. Tube is also held to tighter dimensional tolerances and is available in round, square, rectangular, oval and custom shapes, while pipe is almost always round.
We manufacture tube in SS 304, SS 304L, SS 316, SS 316L and Duplex stainless steel. 304 and 304L suit food processing, architectural and general fabrication work; 316 and 316L add molybdenum for better resistance to chlorides, acids and marine environments and are preferred for chemical, pharmaceutical and offshore use; Duplex offers higher mechanical strength and stress-corrosion-cracking resistance for high-pressure industrial systems. Full grade details are on our Tube Grades page.
Seamless tube is formed by hot extrusion and cold drawing with no welded joint, giving it uniform strength around its circumference — it is the usual choice for high-pressure, high-temperature or safety-critical duty such as boilers, refineries and hydraulic systems. Welded tube is formed by rolling stainless steel strip and joining the seam with TIG, laser or high-frequency welding; modern welding gives good dimensional accuracy and surface finish, and it is well suited to structural fabrication, furniture and moderate-pressure applications. The right choice depends on the pressure, temperature and reliability requirements of your application.
We offer bright annealed, mirror polish, matte, satin and pickled finishes. The finish is applied after cold drawing and straightening, so dimensional accuracy is not affected by the finishing step — the choice is typically driven by whether the application prioritises corrosion resistance, hygiene, or decorative appearance.
Every tube is checked through dimensional inspection, hydrostatic pressure testing, eddy current testing, ultrasonic testing, chemical composition (PMI) analysis, mechanical strength testing, surface finish inspection and visual examination before it leaves our facility, in line with ASTM, ASME, DIN, EN and JIS standards.
Both wall thickness and length can be customised alongside outside diameter. Cold drawing is used specifically to refine wall thickness and OD together while improving concentricity, and tube is supplied in either standard or customised lengths depending on the project.
Beyond round tube, we manufacture square, rectangular and custom profile tube. Square and rectangular tube is widely used in structural fabrication and architecture for its strength-to-weight ratio, load-bearing capability and clean, modern appearance in visible applications like railings and facades.
Perforated tube starts as standard round, square or rectangular tube and has a patterned array of holes formed into the wall, used for filtration, screening, acoustic damping and similar applications where controlled flow-through or sound absorption is needed rather than a solid wall. See our dedicated Perforated Tube page for pattern and sizing detail.
